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INSTANT DOWNLOAD COMPLETE TEST BANK WITH ANSWERS

 

 

Bailey And Scotts Diagnostic Microbiology 13th Edition By Patricia M. – Test Bank

 

 

Sample  Questions

 

Chapter 03: Host-Microorganism Interactions

Test Bank

 

MULTIPLE CHOICE

 

  1. A human infection that results from a microorganism that primarily infects animal populations is referred to as a(n) _________ infection.
a. accidental
b. zoonotic
c. secondary
d. vector

 

 

ANS:  B

Some microorganisms primarily infect animal populations but can occasionally infect humans in what is called a zoonotic infection.

 

REF:   24                  OBJ:   Level: Knowledge

 

  1. The persistent survival of microorganisms on a surface of the human body is called a(n):
a. infection.
b. colonization.
c. nosocomial infection.
d. reservoir.

 

 

ANS:  B

Microorganisms are everywhere in nature, including on and in the human body. Sometimes they do not cause disease but instead coexist with the host.

 

REF:   25                  OBJ:   Level: Knowledge

 

  1. Cells that ingest and destroy bacteria and other foreign particles are called:
a. phagocytes.
b. lymphocytes.
c. goblet cells.
d. ciliated cells.

 

 

ANS:  A

Phagocytes are cells that ingest and destroy invading bacteria when they enter the human body.

 

REF:   28                  OBJ:   Level: Knowledge

 

  1. Cells with a short life span that circulate in blood and tissues and are usually the first cells on the scene of a bacterial invasion are called:
a. monocytes.
b. polymorphonuclear neutrophils.
c. lymphocytes.
d. macrophages.

 

 

ANS:  B

All the cells listed are involved in the body’s cellular responses to foreign particles, but neutrophils are short-lived cells that circulate in blood and tissues.

 

REF:   28                  OBJ:   Level: Knowledge

 

  1. Swelling, redness, heat, and pain are all manifestations of:
a. nosocomial infection.
b. inflammation.
c. bacterial colonization.
d. coagulation.

 

 

ANS:  B

Inflammation is a system that has both cellular and biochemical components that interact in various ways to fight microbial invasion in the human body.

 

REF:   29–30            OBJ:   Level: Knowledge

 

  1. The complement system serves to:
a. increase blood flow to the area of infection and can also effectively wall off the infection through the production of barrier substances.
b. attract and enhance the activities of phagocytes.
c. provide substances secreted by one type of cell, which have substantial effects on the antiinfective activities of other cells.
d. ingest and destroy microorganisms.

 

 

ANS:  B

Because neutrophils and macrophages are widely dispersed throughout the body, the complement system sends signals to attract and concentrate these cells at the point of invasion.

 

REF:   29                  OBJ:   Level: Knowledge

 

  1. The coagulation system serves to:
a. increase blood flow to the area of infection and can also effectively wall off the infection through the production of barrier substances.
b. attract and enhance the activities of phagocytes.
c. provide substances secreted by one type of cell, which have substantial effects on the antiinfective activities of other cells.
d. ingest and destroy microorganisms.

 

 

ANS:  A

The coagulation system increases blood flow and walls off the infection. It accomplishes this through the production of barrier substances.

 

REF:   29                  OBJ:   Level: Knowledge

 

  1. Biochemicals known as cytokines serve to:
a. increase blood flow to the area of infection and can also effectively wall off the infection through the production of barrier substances.
b. attract and enhance the activities of phagocytes.
c. have substantial effects on the activities of other cells.
d. directly kill gram-negative bacteria.

 

 

ANS:  C

A key component of inflammation is the group of cytokines that are substances secreted by macrophages and other cells that enhance the antiinfective activities of other cells.

 

REF:   29                  OBJ:   Level: Knowledge

 

  1. Specific proteins produced by cells of the immune system in response to the presence of foreign molecules that circulate in the serum and are present in secretions such as saliva are called:
a. antigens.
b. immunoglobulins.
c. cytokines.
d. phagogens.

 

 

ANS:  B

Produced by B lymphocytes in response to the presence of foreign molecules, immunoglobulins (antibodies) are present in serum and in secretions such as saliva and are the central molecule of the immune response.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. The antibody that is secreted in various body fluids and primarily protects those body surfaces lined with mucous membranes is:
a. immunoglobulin (Ig) G.
b. IgA.
c. IgM.
d. IgE.

 

 

ANS:  B

Each of the five different classes of antibodies has its distinctive molecular configuration and is involved in the immune reaction in a different way. IgA is secreted in body fluids and primarily protects those body surfaces lined with mucous membranes.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. Which stage of infection is characterized by host deterioration and possibly death?
a. Prodromal
b. Clinical
c. Decline
d. Convalescent

 

 

ANS:  C                    REF:   36                  OBJ:   Level: Knowledge

 

  1. Which immune system cells primarily function as antibody producers and originate from stem cells?
a. B lymphocytes
b. T lymphocytes
c. Natural killer cells
d. Neutrophils

 

 

ANS:  A

Produced by B lymphocytes in response to the presence of foreign molecules, immunoglobulins (antibodies) are present in serum and in secretions such as saliva and are the central molecule of the immune response.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. Which immune system cells destroy infected or malignant host cells?
a. B lymphocytes
b. T lymphocytes
c. Natural killer cells
d. Neutrophils

 

 

ANS:  C

Natural killer cells are an important cellular component of the immune response that serve to destroy infected or malignant host cells.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. Infectious processes that quickly develop are referred to as _________ infections.
a. chronic
b. latent
c. acute
d. nosocomial

 

 

ANS:  C

Depending on the host and microbial factors, infections may develop quickly (acute) or slowly (chronic).

 

REF:   35                  OBJ:   Level: Knowledge

 

  1. Infectious processes that develop and slowly progress are known as _________ infections.
a. chronic
b. latent
c. acute
d. nosocomial

 

 

ANS:  A

Depending on the host and microbial factors, infections may develop quickly (acute) or slowly (chronic).

 

REF:   35                  OBJ:   Level: Knowledge

 

  1. Proper hand-washing and hygiene procedures by hospital staff are essential in preventing which types of infections?
a. Chronic
b. Latent
c. Acute
d. Nosocomial

 

 

ANS:  D

Nosocomial infections are those that are contracted in the hospital environment, sometimes being transmitted by the contact of hospital personnel such as the nursing staff.

 

REF:   23                  OBJ:   Level: Application

 

  1. Which one of the following statements is true regarding endotoxins?
a. They are produced and released by living bacteria.
b. They are associated with gram-positive bacteria.
c. They interrupt protein synthesis.
d. They are released upon cell death.

 

 

ANS:  D

Endotoxins are found within gram-negative bacteria and are released only upon cell lysis and death.

 

REF:   34                  OBJ:   Level: Knowledge

 

  1. A bacterium that normally colonizes the skin gains access through a laceration and causes infection. This type of infection is classified as:
a. nosocomial.
b. opportunistic.
c. nonpathogenic.
d. immunogenic.

 

 

ANS:  B

Although bacteria colonize the skin and are nonpathogenic to the host, they have the ability to cause infection if given the opportunity to penetrate the skin barrier and enter the host’s system.

 

REF:   33                  OBJ:   Level: Knowledge

 

  1. An example of antibody-mediated immunity is:
a. phagocytosis.
b. macrophage release.
c. T-cell activation.
d. B-cell activation.

 

 

ANS:  D

Antibodies are produced by plasma cells that are produced by B cells; therefore, antibody-mediated immunity is observed in B-cell activation.

 

REF:   31                  OBJ:   Level: Knowledge

 

  1. Latent infections are those that:
a. develop and progress slowly.
b. develop quickly and end soon.
c. exist as a silent phase in which the agent is causing no notable effect.
d. develop quickly but last long.

 

 

ANS:  C

Some pathogens, particularly viruses, lie dormant in the body for a time before suddenly becoming active again.

 

REF:   35                  OBJ:   Level: Knowledge

 

  1. Pathogens are able to produce enzymes that directly destroy or inactivate antibodies. These enzymes are referred to as:
a. proteases.
b. nucleases.
c. collagenases.
d. polymerases.

 

 

ANS:  A

Antibodies are classified as proteins, and proteases are enzymes that break down proteins.

 

REF:   34                  OBJ:   Level: Application

 

  1. Botulism and tetanus have the ability to interfere with neuromuscular functions. The toxins they produce are classified as:
a. endotoxins.
b. enterotoxins.
c. exotoxins.
d. emetic toxins.

 

 

ANS:  C

Botulism and tetanus cause a disruption in neuromuscular function by secreting exotoxins into the surrounding environment.

 

REF:   34                  OBJ:   Level: Knowledge

 

  1. IgG is the:
a. first antibody produced when an invading microorganism is initially encountered.
b. antibody that is associated with various parasitic infections.
c. antibody that is secreted in various body fluids and primarily protects those body surfaces lined with mucous membranes.
d. second antibody produced when an invading microorganism is initially encountered and the most abundant.

 

 

ANS:  D

Each of the five different classes of antibodies has its distinctive molecular configuration and is involved in the immune reaction in a different way. IgG is the most abundant and is the second antibody produced when an invading microorganism is initially encountered.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. IgM is the:
a. first antibody produced when an invading microorganism is initially encountered.
b. antibody that is associated with various parasitic infections.
c. antibody that is secreted in various body fluids and primarily protects those body surfaces lined with mucous membranes.
d. second antibody produced when an invading microorganism is initially encountered and the most abundant.

 

 

ANS:  A

Each of the five different classes of antibodies has its distinctive molecular configuration and is involved in the immune reaction in a different way. IgM is the first antibody produced when an invading microorganism is initially encountered.

 

REF:   30                  OBJ:   Level: Knowledge

 

  1. IgE is the:
a. first antibody produced when an invading microorganism is initially encountered.
b. antibody that is associated with various parasitic infections.
c. antibody that is secreted in various body fluids and primarily protects those body surfaces lined with mucous membranes.
d. second antibody produced when an invading microorganism is initially encountered and the most abundant.

 

 

ANS:  B

Each of the five different classes of antibodies has its distinctive molecular configuration and is involved in the immune reaction in a different way. IgE is usually elevated in a parasitic infection.

 

REF:   30                  OBJ:   Level: Knowledge

 

Chapter 07: Traditional Cultivation and Identification

Test Bank

 

MULTIPLE CHOICE

 

  1. Organisms that have nutritional needs that are relatively complex and require extra media components to be used for growth are called:
a. fastidious.
b. capnophiles.
c. neutrophils.
d. halophiles.

 

 

ANS:  A

Fastidious organisms require special nutrients to grow in the laboratory.

 

REF:   81                  OBJ:   Level: Knowledge

 

  1. The role of the agar ingredient in culture medium is to:
a. provide a nutritional base for bacterial metabolism.
b. solidify the medium and provide a stable culture surface.
c. sterilize the medium and prevent contamination.
d. support the growth of only pathogenic organisms.

 

 

ANS:  B

Agarose is a solidifying agent used to make bacterial medium solid for the growth of colonies of bacteria.

 

REF:   82                  OBJ:   Level: Knowledge

 

  1. A bacterial colony can be described as:
a. sufficiently large numbers of a bacterium that can be observable with the unaided eye.
b. derived from many different types of bacterial cells.
c. belonging to different genera and species.
d. having different genetic and phenotypic characteristics.

 

 

ANS:  A

The multiplication of a single bacterial cell into a heap of cells large enough to be observed with the naked eye results in a colony.

 

REF:   81                  OBJ:   Level: Knowledge

 

  1. Which category of media can be described as containing specific nutrients required for the growth of particular bacterial pathogens in a patient specimen?
a. Enrichment
b. Supportive
c. Selective
d. Differential

 

 

ANS:  A

Enrichment media are used to enhance the growth of a particular pathogen from a mixture of organisms.

 

REF:   82                  OBJ:   Level: Knowledge

 

  1. Which category of media can be described as containing nutrients that support the growth of the most nonfastidious organisms without giving any particular organism a growth advantage?
a. Enrichment
b. Supportive
c. Selective
d. Differential

 

 

ANS:  B

Many different types of media exist and serve different purposes in clinical microbiology. Some types are basically nutritive and support the growth of many different types of microorganisms.

 

REF:   83                  OBJ:   Level: Knowledge

 

  1. Which category of media can be described as containing some factor or factors that allow colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics that can be used to distinguish them from other bacteria growing on the same agar plate?
a. Enrichment
b. Supportive
c. Selective
d. Differential

 

 

ANS:  D

Many different types of media exist and serve different purposes in clinical microbiology. Some types are differential in that they allow the discrimination of microorganisms on the basis of certain growth characteristics.

 

REF:   83                  OBJ:   Level: Knowledge

 

  1. Which category of media can be described as containing one or more agents that are inhibitory to all organisms except those being sought?
a. Enrichment
b. Supportive
c. Selective
d. Differential

 

 

ANS:  C

Many different types of media exist and serve different purposes in clinical microbiology. Some types are selective in that they contain antimicrobials, dyes, or alcohol that support the growth of one group of organisms but not another.

 

REF:   83                  OBJ:   Level: Knowledge

 

  1. In which category of media would MacConkey agar best fit?
a. Selective
b. Differential
c. Selective and differential
d. Supportive only

 

 

ANS:  C

MacConkey agar contains crystal violet to inhibit gram-positive bacteria and fungi, allowing gram-negative bacilli to grow.

 

REF:   86                  OBJ:   Level: Application

 

  1. In which category of media would blood agar best fit?
a. Selective
b. Differential
c. Selective and differential
d. Supportive only

 

 

ANS:  B

Blood agar allows the differentiation of various bacteria on the basis of the type of hemolysis present.

 

REF:   87                  OBJ:   Level: Application

 

  1. In which category of media would Löwenstein-Jensen medium best fit?
a. Selective
b. Differential
c. Selective and differential
d. Supportive only

 

 

ANS:  A

Löwenstein-Jensen medium contains malachite green to inhibit most bacteria and allow mycobacteria to grow. Factors in the media allow the mycobacteria to grow while other bacteria are inhibited. The media however does not differentiate between the various species in the mycobacteria genera. Biochemical testing is required for speciation.

 

REF:   83                  OBJ:   Level: Application

 

  1. Which medium can be described as a nutritionally rich medium used to grow various microorganisms, either as a broth or as an agar, with or without added blood?
a. Chocolate
b. Colistin, nalidixic acid (CNA) blood
c. Brain-heart infusion (BHI)
d. Thioglycollate

 

 

ANS:  C

BHI is a nutritionally rich medium that is used as both a broth and as an agar and comes with or without added blood.

 

REF:   86                  OBJ:   Level: Knowledge

 

  1. Which medium can be described as containing hemoglobin, hemin (X factor), and the co-enzyme nicotinamide adenine dinucleotide (NAD) (V factor)?
a. Chocolate
b. CNA blood
c. BHI
d. Thioglycollate

 

 

ANS:  A

Chocolate agar contains extra nutrients that are released into the agar by the lysis of the blood additive. These nutrients include hemoglobin, hemin, and NAD.

 

REF:   86                  OBJ:   Level: Knowledge

 

  1. Which medium can be described as suppressing the growth of most gram-negative organisms while allowing gram-positive bacteria to grow?
a. Chocolate
b. CNA blood
c. BHI
d. Thioglycollate

 

 

ANS:  B

CNA blood agar contains colistin and nalidixic acid, which inhibit most gram-negative organisms while allowing gram-positive bacteria to grow.

 

REF:   86                  OBJ:   Level: Knowledge

 

  1. Which medium can be described as containing bile salts and dyes (e.g., bromothymol blue, acid fuchsin) to slow selectively the growth of most nonpathogenic gram-negative bacilli found in the gastrointestinal tract and allow Salmonella spp. and Shigella spp. to grow?
a. Thayer-Martin agar
b. MacConkey agar
c. Phenylethyl alcohol (PEA)
d. Hektoen enteric agar

 

 

ANS:  D

Hektoen enteric agar contains bile salts, bromothymol blue, and acid fuchsin to inhibit the growth of nonpathogenic, gram-negative bacilli and allows Salmonella spp. and Shigella spp. to grow.

 

REF:   86                  OBJ:   Level: Knowledge

 

  1. Which medium can be described as containing crystal violet dye to inhibit the growth of gram-positive bacteria and fungi and allows many types of gram-negative bacilli to grow?
a. Thayer-Martin agar
b. MacConkey agar
c. PEA
d. Hektoen enteric agar

 

 

ANS:  B

MacConkey agar contains crystal violet dye to inhibit the growth of gram-positive bacteria and fungi and allows many types of gram-negative bacilli to grow.

 

REF:   86–87            OBJ:   Level: Knowledge

 

  1. What name is given to the type of hemolysis that produces incomplete hemolysis and a greening discoloration of the medium?
a. Beta
b. Gamma
c. Alpha
d. Kappa

 

 

ANS:  C

The type of hemolysis described is alpha. Partial lysis of erythrocytes causes the greening of the agar.

 

REF:   87                  OBJ:   Level: Knowledge

 

  1. What name is given to the type of hemolysis that produces complete hemolysis and a clearing of the medium?
a. Beta
b. Gamma
c. Alpha
d. Kappa

 

 

ANS:  A

The type of hemolysis described is beta. Complete lysis of erythrocytes causes clearing of the agar.

 

REF:   87                  OBJ:   Level: Knowledge

 

  1. To read the hemolytic reaction accurately on a blood agar plate, the technologist must:
a. hold the plate up to the light, and observe the plate with the light coming from behind.
b. hold the plate under the light, and observe the plate with the light coming from the top.
c. hold the plate over a white background.
d. examine the plate using reflected and transmitted light.

 

 

ANS:  A

Transmitted light (i.e., passing through the agar) is required to interpret the hemolytic reaction properly on blood agar.

 

REF:   87                  OBJ:   Level: Knowledge

 

  1. Which group of bacteria uses oxygen as a terminal electron acceptor and grows well in ambient air?
a. Aerobes
b. Anaerobes
c. Capnophiles
d. Microaerophiles

 

 

ANS:  A

Various types of microorganisms require different atmospheric conditions. Aerobes grow best in the presence of ambient air.

 

REF:   89                  OBJ:   Level: Knowledge

 

  1. Increased concentrations of carbon dioxide (CO2) (5% to 10%) and approximately 15% oxygen (O2) produce an environmental condition that best suits which type of organism?
a. Aerobes
b. Anaerobes
c. Capnophiles
d. Microaerophiles

 

 

ANS:  C

Various types of microorganisms require different atmospheric conditions. Capnophiles grow best in the presence of increased levels of CO2.

 

REF:   89                  OBJ:   Level: Knowledge

 

  1. Reduced O2 (5% to 10%) and increased CO2 (8% to 10%) produce an environmental condition that best suits which type of organism?
a. Aerobes
b. Anaerobes
c. Capnophiles
d. Microaerophiles

 

 

ANS:  D

Various types of microorganisms require different atmospheric conditions. Microaerophiles grow best in the presence of reduced of O2 and increased CO2.

 

REF:   89                  OBJ:   Level: Knowledge

 

  1. A candle jar is used to cultivate which type of bacteria?
a. Aerobes
b. Anaerobes
c. Capnophiles
d. Microaerophiles

 

 

ANS:  C

The burning candle in the jar lowers the O2 level and raises the CO2 level, allowing capnophiles to grow.

 

REF:   90                  OBJ:   Level: Application

 

  1. The most medically important bacteria sought in the medical laboratory are cultivated using incubators with temperatures maintained in what range?
a. 35° to 37° C
b. 30° to 35° C
c. 37° to 39° C
d. 25° to 35° C

 

 

ANS:  A

Temperatures of 35° to 37° C simulate those found in the body and best allow pathogens to grow.

 

REF:   89                  OBJ:   Level: Knowledge

 

  1. An oxidase test was performed on two organisms for quality control purposes. Pseudomonas aeruginosa and Stenotrophomonas maltophilia tested positive and negative, respectively. Which of the following statements explains this discrepancy?
a. The oxidase reagent is most likely expired.
b. The organisms are most likely old and therefore are not properly reacting.
c. These organisms are poor choices for quality control purposes; both are oxidase-negative organisms.
d. No discrepancy is present. The correct results are obtained.

 

 

ANS:  D

  1. aeruginosa and S. maltophilia are oxidase-positive and oxidase-negative organisms, respectively; therefore the results are accurate.

 

REF:   97                  OBJ:   Level: Problem Solving

 

  1. A positive pyrrolidonyl arylamidase (PYR) test was observed on a species of Enterococcus. What color should be observed for this reaction?
a. Purple
b. Red
c. Green
d. Pink

 

 

ANS:  B

A positive PYR test produces a red color. Enterococcus spp. are PYR positive; therefore a red color would result.

 

REF:   97                  OBJ:   Level: Application

 

  1. Oxidative or fermentative media were set up on an organism suspected of being Pseudomonas aeruginosa. What results would be expected?
a. Yellow in both tubes
b. Green in both tubes
c. Yellow in the open tube and green in the closed tube
d. Green in the open tube and yellow in the closed tube

 

 

ANS:  C

  1. aeruginosa is an oxidative organism; therefore only the open tube (i.e., oxidative tube) reacts and produces a yellow color. The fermentative tube (i.e., anaerobic) remains green.

 

REF:   98                  OBJ:   Level: Application

 

  1. Generation time can be defined as the:
a. time required for a bacterial population to double.
b. time required for a bacterial population to triple.
c. time required for a bacterial population to quadruple.
d. half-life of bacteria.

 

 

ANS:  A

Generation time is the time required for a bacterial population to double.

 

REF:   101                OBJ:   Level: Knowledge

 

  1. A catalase test was performed from a sheep blood agar plate on a colony of streptococci, and bubbling was observed. Which of the following statements explains this discrepancy?
a. Catalase is the inappropriate test to use on colonies of streptococci; therefore the results are invalid.
b. The colony may have been contaminated with sheep red blood cells, causing a false-positive result.
c. The colony was most likely enterococci, not streptococci.
d. No discrepancy is present. Streptococcus is a catalase-positive colony.

 

 

ANS:  B

Sheep red blood cells produce catalase; therefore if some of the media was incorporated into the colony, a false-positive result would occur, because streptococci are catalase-negative colonies.

 

REF:   97                  OBJ:   Level: Problem Solving

 

  1. Which of the following organisms grows best at 42º C?
a. Streptococcus pneumonia
b. Haemophilus influenza
c. Neisseria gonorrhoeae
d. Campylobacter jejuni

 

 

ANS:  D

Campylobacter jejuni grows best at 42º C. The remaining organisms are fastidious and require increased oxygen concentrations at 35º to 37º C.

 

REF:   96                  OBJ:   Level: Application

 

  1. Escherichia coli, a member of the family Enterobacteriaceae, was resistant to the antibiotic vancomycin. Which of the following statements explains this discrepancy?
a. The vancomycin disk has most likely expired.
b. Vancomycin should only be used in viral infections, not bacterial infections.
c. The plate is most likely contaminated with another organism.
d. No discrepancy is present. E. coli is resistant to vancomycin.

 

 

ANS:  D

Vancomycin works best on gram-positive organisms. E. coli is a gram-negative bacterium and therefore is resistant to vancomycin; most clinically relevant gram-negative bacteria are resistant to vancomycin.

 

REF:   96                  OBJ:   Level: Problem Solving

 

 

Chapter 17: Listeria, Corynebacterium, and Similar Organisms

Test Bank

 

MULTIPLE CHOICE

 

  1. A catalase-positive, gram-positive bacillus that is not acid-fast, does not branch, and does not form spores could possibly belong to which group of bacteria?
a. Corynebacterium
b. Bacillus
c. Actinomyces
d. Mycobacterium

 

 

ANS:  A

The genera described in this chapter, including Corynebacterium species, are all catalase-positive, gram-positive rods. They are not acid-fast, most do not branch, and they do not form spores.

 

REF:   271                OBJ:   Level: Knowledge

 

  1. Bacteria described as being coryneform have which of the following morphologic features?
a. Squared rods with squared ends arranged in pairs
b. Short gram-positive cocci in branching chains
c. Resemble and are often referred to as Chinese letters
d. Long branching gram-positive bacilli

 

 

ANS:  C

Most of the genera in this chapter (except Listeria, Rothia, and Oerskovia) are classified as coryneform bacteria, that is, they are gram-positive and have short or slightly curved rods with rounded ends; some have rudimentary branching. Cells are arranged singly in “palisades” of parallel cells or in pairs that remain connected after cell division to form V or L shapes. Groups of these morphologic characteristics observed together resemble, and are often referred to as, Chinese letters.

 

REF:   275                OBJ:   Level: Knowledge

 

  1. A cerebrospinal fluid (CSF) culture was performed on a newborn in distress. After overnight incubation, small gram-positive bacilli with a soft zone of beta hemolysis grew on sheep blood agar. Based on this information, what results would be expected on the following tests: hippurate; Christie, Atkins, Munch-Petersen (CAMP); and motility?
a. Negative hippurate, positive CAMP, and negative motility
b. Positive hippurate, negative CAMP, and positive motility
c. Positive hippurate, positive CAMP, and positive motility
d. Negative hippurate, negative CAMP, and negative motility

 

 

ANS:  C

The organism is Listeria monocytogenes and produces positive results for the hippurate, CAMP, and motility tests. Gram-positive bacilli with a soft zone of beta hemolysis are characteristic of L. monocytogenes, along with the above biochemicals.

 

REF:   280                OBJ:   Level: Problem Solving

 

  1. The organism that exhibits characteristic end-over-end tumbling motility when incubated in nutrient broth at room temperature for 1 to 2 hours is:
a. Listeria monocytogenes.
b. Corynebacterium diphtheriae.
c. Bacillus anthracis.
d. Bacillus cereus.

 

 

ANS:  A

Listeria monocytogenes can be presumptively identified by observation of motility by direct wet mount. The organism exhibits characteristic end-over-end tumbling motility when incubated in nutrient broth at room temperature for 1 to 2 hours.

 

REF:   279                OBJ:   Level: Knowledge

 

  1. The isolation of a small gram-positive, catalase-positive rod with a narrow zone of beta hemolysis isolated from blood or CSF should be used as strong presumptive evidence for:
a. listeriosis.
b. diphtheria.
c. pertussis.
d. tetanus.

 

 

ANS:  A

  1. monocytogenes ferments glucose and is Voges-Proskauer– and esculin-positive. The isolation of a small gram-positive, catalase-positive rod with a narrow zone of beta hemolysis isolated from blood or CSF should be used as strong presumptive evidence for listeriosis.

 

REF:   279                OBJ:   Level: Knowledge

 

  1. Patients who are immunocompromised and women who are pregnant should avoid eating soft cheeses such as Mexican-style, feta, Brie, Camembert, and blue-veined cheeses to prevent:
a. foodborne listeriosis.
b. staphylococcal food poisoning.
c. gastric gangrene.
d. Salmonella infection.

 

 

ANS:  A

Patients who are immunocompromised may prevent foodborne listeriosis by avoiding soft cheeses such as Mexican-style, feta, Brie, Camembert, and blue-veined cheeses. In addition, leftover or ready-to-eat foods such as hot dogs or cold cuts should be thoroughly heated before consuming them.

 

REF:   285                OBJ:   Level: Knowledge

 

  1. After 48 hours of incubation, black colonies with a dark brown halo are observed on Tinsdale agar. What type of toxin does this organism produce?
a. Emetic toxin
b. Exotoxin
c. Enterotoxin
d. Endotoxin

 

 

ANS:  B

  1. diphtheriae produces black colonies with a dark brown halo on Tinsdale agar and is also a potent exotoxin.

 

REF:   275                OBJ:   Level: Application

 

  1. A gram-positive bacillus, which grew on Tinsdale agar, is esculin hydrolysis–negative, urease-positive, and nonlipophilic. The organism can be identified as:
a. C. diphtheria (subsp. gravis).
b. C. imitans.
c. C. xerosis.
d. C. ulcerans.

 

 

ANS:  D

  1. ulcerans is esculin hydrolysis–negative, urease-positive, and nonlipophilic. The other species are all urease negative.

 

REF:   282                OBJ:   Level: Application

 

  1. Quality control is set up on urea media. Which two organisms should be used to determine the validity of the media?
a. C. ulcerans and C. diphtheria (subsp. mitis)
b. C. diphtheria (subsp. gravis) and C. diphtheria (subsp. intermedius)
c. C. ulcerans and C. pseudotuberculosis
d. C. diphtheria (subsp. belfanti) and C. diphtheria (subsp. gravis)

 

 

ANS:  A

The only organisms that are positive and negative for urea are C. ulcerans and C. diphtheria (subsp. mitis). The other organisms are either both positive or both negative for urea.

 

REF:   282                OBJ:   Level: Application

 

  1. A pharyngeal specimen is inoculated on cystine-tellurite blood agar, modified Tinsdale agar, and MacConkey agar. After 48 hours of incubation, black colonies with a brown halo are observed on the Tinsdale agar and gray colonies are isolated from the cystine-tellurite agar. However, no growth is observed on the MacConkey agar. Which one of the following statements explains this discrepancy?
a. The MacConkey agar is most likely expired.
b. The MacConkey agar should be incubated an additional 24 hours to observe growth.
c. The pH of the media may be altered, causing an environment that is too acidic for the organism to grow.
d. No discrepancy is present; this organism does not grow on MacConkey agar.

 

 

ANS:  D

The organism is C. diphtheria and therefore can grow on Tinsdale agar but fails to grow on MacConkey agar.

 

REF:   275                OBJ:   Level: Application

Chapter 27: Sphingomonas paucimobilis and Similar Organisms

Test Bank

 

MULTIPLE CHOICE

 

  1. A yellow-pigmented, gram-negative rod on blood agar that is oxidase-positive, motile by wet mount, and has the ability to oxidize glucose, xylose, and sucrose is most likely which of the following?
a. Treponema
b. Leptospira
c. Borrelia
d. Sphingomonas

 

 

ANS:  D

All these characteristics can be used to describe Sphingomonas.

 

REF:   376                OBJ:   Level: Knowledge

 

  1. Oxidase-positive, glucose-positive, (oxidatively) gram-negative bacilli that cannot grow on MacConkey agar include:
a. Pseudomonas.
b. Vibrio.
c. Stenotrophomonas.
d. Sphingomonas.

 

 

ANS:  D

All of these characteristics can be used to describe Sphingomonas.

 

REF:   376                OBJ:   Level: Knowledge

 

  1. Which of the following statements best describes the habitats of Acidovorax, Sphingobacterium, and Sphingomonas?
a. Habitats are limited to the upper respiratory tract of various mammals.
b. Habitats are unknown.
c. Habitats are limited to the soil and water environment.
d. Habitats are limited mostly to water sources.

 

 

ANS:  B

These organisms are rarely isolated from human materials, and they have an extremely limited role as agents of infection. Because they are rarely encountered in the clinical setting, little information exists regarding their epidemiologic patterns, capacity to cause human infections, and potential for antimicrobial resistance.

 

REF:   374                OBJ:   Level: Knowledge

 

  1. Although no definitive guidelines are available for the treatment of Sphingomonas paucimobilis infections, which antibiotic appears to have potential activity against this organism?
a. Penicillin
b. Trimethoprim-sulfamethoxazole combination
c. Flagyl
d. Imipenem

 

 

ANS:  B

Antimicrobic susceptibility indicates that S. paucimobilis is susceptible to tetracycline, chloramphenicol, trimethoprim-sulfamethoxazole combination, and aminoglycosides.

 

REF:   378                OBJ:   Level: Knowledge

 

  1. When performing quality control on motility media, which of the following organisms should be used?
a. Acidovorax facilis and Sphingomonas spp.
b. Centers for Disease Control and Prevention (CDC) group IIc and CDC group IIe
c. CDC group Iii and Sphingobacterium mizutaii
d. CDC group IIh and Acidovorax facilis

 

 

ANS:  D

CDC group IIh and Acidovorax facilis are two organisms that are negative and positive, respectively, for motility.

 

REF:   376                OBJ:   Level: Application

 

Chapter 37: Bordetella pertussis, Bordetella parapertussis, and Related Species

Test Bank

 

MULTIPLE CHOICE

 

  1. Pertussis (whooping cough) is an epidemic disease that is a highly contagious, acute infection of the upper respiratory tract caused by the:
a. Brucella spp.
b. Bordetella spp.
c. Pasteurella spp.
d. Francisella spp.

 

 

ANS:  B

Before the introduction of vaccines and in populations in which immunization is not performed, pertussis (whooping cough) is an epidemic disease with cycles every 2 to 5 years. Pertussis is a highly contagious, acute infection of the upper respiratory tract caused primarily by Bordetella pertussis and less commonly by B. parapertussis.

 

REF:   434                OBJ:   Level: Knowledge

 

  1. The mode of transmission of Bordetella pertussis can best be described as:
a. person-to-person contact.
b. exposure to contaminated water.
c. inhalation of contaminated air.
d. close contact with animals.

 

 

ANS:  A

Infection by B. pertussis is transmitted from person to person, presumably by airborne transmission from the cough of an infected person. Humans are the only reservoir.

 

REF:   434                OBJ:   Level: Knowledge

 

  1. During the catarrhal stage of pertussis, symptoms are:
a. runny nose and mild cough.
b. severe and violent coughing.
c. vomiting and “whooping” as air is rapidly inspired into the lungs past a swollen glottis.
d. lymphocytosis and fever.

 

 

ANS:  A

Classic pertussis is usually a disease of children and can be divided into three symptomatic stages: catarrhal, paroxysmal, and convalescent. During the catarrhal stage, symptoms are the same as a mild cold with a runny nose and mild cough; this stage may last for several weeks.

 

REF:   435                OBJ:   Level: Knowledge

 

  1. During the paroxysmal stage of pertussis, symptoms are:
a. runny nose and mild cough.
b. severe and violent coughing.
c. neutrocytosis and fever.
d. lymphadenitis.

 

 

ANS:  B

Classic pertussis is usually a disease of children and can be divided into three symptomatic stages: catarrhal, paroxysmal, and convalescent. After the catarrhal stage, episodes of severe and violent coughing increase in number, marking the beginning of the paroxysmal stage.

 

REF:   435                OBJ:   Level: Knowledge

 

  1. Acceptable specimens for the detection of Bordetella pertussis are:
a. throat swabs.
b. sputum.
c. nasopharyngeal aspirates.
d. anterior nose swabs.

 

 

ANS:  C

Nasopharyngeal aspirates or nasopharyngeal swabs (e.g., calcium alginate, Dacron on a wire handle) are acceptable specimens because B. pertussis colonizes the ciliated epithelial cells of the upper respiratory tract. Specimens obtained from the throat, sputum, or anterior nose are unacceptable because these sites are not lined with ciliated epithelium. For collection, the swab is bent to conform to the nasal passage and held against the posterior aspect of the nasopharynx. If coughing does not occur, then another swab is inserted into the other nostril to initiate the cough. The swab is left in place during the entire cough, removed, and then immediately inoculated onto a selective medium at the bedside.

 

REF:   435                OBJ:   Level: Knowledge

 

  1. Because of its longer shelf life, the medium of choice to cultivate Bordetella spp. is:
a. buffered charcoal yeast extract (BCYE).
b. thiosulfate citrate bile salts sucrose (TCBS) agar.
c. Bordet-Gengou agar.
d. Regan-Lowe agar.

 

 

ANS:  D

Regan-Lowe agar contains charcoal agar with 10% horse blood and cephalexin and has a 4- to 8-week shelf life, whereas Bordet-Gengou agar contains potato infusion agar with glycerol and sheep blood with methicillin or cephalexin and has a short shelf life. BCYE is the medium of choice for cultivating Legionella spp., and TCBS is the medium of choice for cultivating Vibrio spp.

 

REF:   436                OBJ:   Level: Knowledge

 

  1. Which of the following toxins contributes to the virulence of Bordetella pertussis and works by hemolyzing red cells and activating cyclic adenosine monophosphate, which inactivates several types of host immune cells?
a. Endotoxin
b. Pertussis toxin
c. Tracheal cytotoxin
d. Adenylate cyclase toxin

 

 

ANS:  D

Adenylate cyclase toxin hemolyzes red cells and activates cyclic adenosine monophosphate, thereby inactivating several types of host immune cells. Pertussis toxin induces lymphocytosis and suppresses chemotaxis and oxidative responses in neutrophils and macrophages. Tracheal cytotoxin causes ciliary dysfunction and damage, and endotoxin is a lipopolysaccharide released upon cell death.

 

REF:   435                OBJ:   Level: Knowledge

 

  1. Bordetella pertussis colonies growing on Regan-Lowe medium yields which of the following colonial morphologic appearances?
a. Star-shaped colonies
b. Mercury-drop colonies
c. Yellow-pigmented colonies
d. Shiny black-pigmented colonies

 

 

ANS:  B

Young colonies of B. pertussis and B. parapertussis are small and shiny, resembling mercury drops; colonies become whitish-gray with age (Figure 37-1).

 

REF:   436                OBJ:   Level: Knowledge

 

  1. A nasopharyngeal aspirate is cultured on Bordet-Gengou agar, and growth is observed. The colonies are also subjected to a direct fluorescent antibody (DFA) stain, which is also positive. On the basis of these findings, the antimicrobial therapy that should be administered to the patient is:
a. azithromycin.
b. gentamycin.
c. streptomycin.
d. imipenem.

 

 

ANS:  A

Laboratories do not currently perform routine susceptibility testing of B. pertussis and B. parapertussis because the organisms remain susceptible to erythromycin or the newer macrolides (e.g., clarithromycin, azithromycin), ketolides, quinolones, and additional antibiotics such as tetracyclines, chloramphenicol, and trimethoprim-sulfamethoxazole combination. However, because of three erythromycin-resistant isolates of B. pertussis, continued surveillance of B. pertussis is advised.

 

REF:   437                OBJ:   Level: Application

 

  1. If real-time polymerase chain reaction (PCR) is performed on a Bordetella isolate, then it must be noted that this type of swab is unacceptable for collection because of the presence of which of the following inhibitory factors?
a. Dacron
b. Cotton
c. Rayon
d. Calcium alginate

 

 

ANS:  D

Calcium alginate swabs with aluminum shafts are not recommended for PCR; they may inhibit the polymerase enzyme in PCR detection. In addition, cotton swabs may be inhibitory to specimen growth and are also not recommended.

 

REF:   435                OBJ:   Level: Knowledge

 

Chapter 47: Laboratory Methods for Diagnosis of Parasitic Infections: Overview

Test Bank

 

MULTIPLE CHOICE

 

  1. This protozoa has a trophozoite stage but no cyst stage and reproduces via longitudinal binary fission. The parasite belongs to which category?
a. Amebae
b. Flagellates
c. Ciliates
d. Microsporidia

 

 

ANS:  B

Both D. fragilis (internal flagella) and the genus, Trichomonas, have a trophozoite stage but no cyst stage. Reproduction occurs by longitudinal binary fission. Both parasites are flagellates.

 

REF:   545                OBJ:   Level: Application

 

  1. Babesia spp. is transmitted via the bite of a tick and can cause severe disease in patients who have been splenectomised or who are immunocompromised. To diagnose accurately these patient populations, the specimen of choice is:
a. stool.
b. urine.
c. genital sample.
d. blood.

 

 

ANS:  D

Babesia spp. is identified in blood films, is tickborne, and can cause severe disease in patients who have been splenectomised or who are otherwise immunologically compromised.

 

REF:   545                OBJ:   Level: Application

 

  1. Wuchereria, Brugia, Loa, and Onchocerca are all classified as:
a. intestinal cestodes.
b. tissue nematodes.
c. filarial nematodes.
d. blood trematodes.

 

 

ANS:  C

Wuchereria, Brugia, Loa, and Onchocerca are all filarial nematodes. Diagnosis is made on the basis of the recovery and identification of the larval worms (microfilariae) in the blood, other body fluids, or skin.

 

REF:   546                OBJ:   Level: Knowledge

 

  1. A bone marrow aspirate is examined for the presence of parasites from a patient who has been traveling in Latin America for several months and who came in contact with a triatomid bug. Which parasite will most likely be identified?
a. Trypanosoma cruzi
b. Dientamoeba fragilis
c. Fasciola hepatica
d. Chilomastix mesnili

 

 

ANS:  A

Bone marrow aspirates for Leishmania and Trypanosoma cruzi amastigotes, or Plasmodium spp., require staining using any of the bloodstains (e.g., Giemsa, Wright, Wright-Giemsa, rapid stains, Field). The examination of specimens may confirm an infection previously missed by examination of routine blood films. The transmission of T. cruzi is through the infected feces of the triatomid bug. The bug takes a blood meal and immediately defecates, and the human host scratches the infected feces into the bite site. Bug saliva contains an irritant that stimulates scratching.

 

REF:   574                OBJ:   Level: Application

 

  1. The eggs of which of the following intestinal parasites are not commonly found in feces and must be detected by other diagnostic techniques?
a. Giardia lamblia
b. Cryptosporidium parvum
c. Clonorchis sinensis
d. Enterobius vermicularis

 

 

ANS:  D

Because the eggs of E. vermicularis are usually deposited around the anus, they are not commonly found in feces and must be detected by other diagnostic techniques. The diagnosis of pinworm infection is usually made on the basis of the recovery of typical eggs, which are described as thick-shelled, football-shaped eggs with one slightly flattened side.

 

REF:   570                OBJ:   Level: Knowledge

 

  1. Which of the following intestinal parasites is found in humans and also in pigs?
a. Giardia lamblia
b. Dientamoeba fragilis
c. Cryptosporidium spp.
d. Balantidium coli

 

 

ANS:  D

  1. coli is generally found in humans, but it is also found in pigs. In some areas of the world, pigs are considered important reservoir hosts for B. coli. It is classified as a ciliate, and humans acquire infections by ingesting food or water contaminated with fecal material containing the resistant, infective cyst stage of the protozoa.

 

REF:   553                OBJ:   Level: Knowledge

 

  1. Some strains of leishmaniae have reservoir hosts, including dogs and wild rodents. Transmission is via the bite of a:
a. tsetse fly.
b. tick.
c. sandfly.
d. triatomid bug.

 

 

ANS:  C

Some strains of leishmaniae have reservoir hosts, including dogs for the Mediterranean strain of Leishmania donovani and wild rodents for the African strain of L. donovani. In addition, L. tropica has been linked to the same two types of animal reservoirs. Transmission is via the bite of infected sandflies. Infection can also occur from person to person (cutaneous lesions), blood transfusion, shared needles, and organ transplants.

 

REF:   568                OBJ:   Level: Knowledge

 

  1. A 17-year-old male with a severe eye infection admits that he does not clean his contact lenses as often as he should. His eye infection is most likely the result of which parasite?
a. Toxoplasma gondii
b. Isospora belli
c. Strongyloides stercoralis
d. Acanthamoeba spp.

 

 

ANS:  D

The free-living amebae, Acanthamoeba spp., is linked to poor contact lens hygiene, which can result in eye infections.

 

REF:   557                OBJ:   Level: Knowledge

 

  1. A 7-year-old girl was at summer camp and dove into the lake many times. She complained that water went up her nose a few times. Several days later she is unresponsive and comatose and rushed to the hospital. A cerebrospinal fluid (CSF) specimen is drawn, and several motile amebae are observed. She is most likely suffering from an infection with which of the following parasites?
a. Plasmodium vivax
b. Naegleria fowleri
c. Ascaris lumbricoides
d. Hymenolepis nana

 

 

ANS:  B

Infection with N. fowleri occurs through contact with contaminated water. Organisms enter through the nasal mucosa and may travel via the olfactory nerve to the brain. N. fowleri can cause a severe and life-threatening disease, such as primary amebic meningoencephalitis (PAM).

 

REF:   558                OBJ:   Level: Application

 

  1. The specimen of choice to collect in suspected cases of Paragonimus infection is:
a. sputum.
b. blood.
c. urine.
d. stool.

 

 

ANS:  A

Sputum is the specimen of choice in suspected cases of Paragonimus spp. Infection in the lungs can be severe with coughing and shortness of breath.

 

REF:   573                OBJ:   Level: Knowledge

 

  1. Which of the following is currently the only fixative available that does not contain formalin, polyvinyl alcohol (PVA), or mercury?
a. Merthiolate-iodine-formalin (MIF)
b. Sodium acetate–acetic acid–formalin (SAF)
c. ECOFIX
d. TOTAL-FIX

 

 

ANS:  D

Currently, TOTAL-FIX is the only fixative that contains no formalin, PVA, or mercury. Examples of semi-universal fixatives are SAF, which has no mercury or PVA but contains formalin; and ECOFIX, which has no mercury or formalin but contains PVA. MIF contains formalin.

 

REF:   562                OBJ:   Level: Knowledge

 

  1. The concentration protocol of the ova and parasite (O&P) examination:
a. requires freshly passed, unpreserved stool.
b. is designed to allow the detection of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae.
c. is microscopically examined at low, high dry, and oil immersion magnifications.
d. is designed to facilitate the identification of intestinal protozoa.

 

 

ANS:  B

The O&P examination is made up of three separate protocols: (1) the direct wet mount, (2) the concentration, and (3) the permanent stained smear. The second part of the O&P examination is the concentration, which is designed to facilitate the recovery of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae. Both flotation and sedimentation methods are available; the most common procedure is the formalin-ethyl acetate sedimentation method (formerly called the formalin-ether method). The concentrated specimen is examined as a wet preparation, with or without iodine, using low and high dry magnifications (100´, 400´) as indicated for the direct wet smear examination.

 

REF:   569                OBJ:   Level: Knowledge

 

  1. The permanent stained smear protocol of the O&P examination:
a. requires freshly passed, unpreserved stool.
b. is designed to allow the detection of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae.
c. is microscopically examined at low, high dry, and oil immersion magnifications.
d. is designed to facilitate the identification of intestinal protozoa.

 

 

ANS:  D

The permanent stained smear is designed to facilitate the identification of intestinal protozoa. Several staining methods are available; the two most common methods are the Wheatley modification of the Gomori tissue trichrome and the iron hematoxylin stains. This part of the O&P examination is critical for the confirmation of suspicious objects observed in the wet examination and for the identification of protozoa that might not have been seen in the wet preparation. The permanent stained smear is the most important procedure performed for the identification of intestinal protozoan infections; the permanent stained smears are examined using oil immersion objectives (600´ for screening, 1000´ for final review of 300 oil immersion fields).

 

REF:   569                OBJ:   Level: Knowledge

 

  1. A 4-year-old boy who is in day care 3 days per week is irritable and scratching the area around his anus. What morphologic characteristics would most likely be observed on microscopic examination of the appropriate specimen?
a. Large eggs, proglottid shape
b. Large eggs with a terminal spine
c. Two individual hooklets
d. Football-shaped eggs with one flattened side

 

 

ANS:  D

The causative agent of pinworm is Enterobius vermicularis. Diagnosis of pinworm infection is usually made on the basis of the recovery of typical eggs, which are described as thick-shelled, football-shaped eggs with one slightly flattened side. Each egg often contains a fully developed embryo and will be infective within a few hours after being deposited.

 

REF:   570                OBJ:   Level: Application

 

  1. The Entero-Test capsule technique involves the collection of duodenal contents to examine the presence of which of the following parasites?
a. Toxoplasma gondii
b. Giardia lamblia
c. Entamoeba histolytica
d. Trichinella spiralis

 

 

ANS:  B

The Entero-Test is a duodenal capsule technique that is a simple and convenient method for the collection of duodenal contents, eliminating the need for intestinal intubation. The technique involves using a length of nylon cord coiled inside a gelatin capsule. The cord protrudes through one end of the capsule and is taped to the side of the patient’s face. The capsule is then swallowed. The gelatin dissolves in the stomach, and the weighted cord is carried by peristalsis into the duodenum. The cord is attached to the weight by a slipping mechanism; the weight is released and passes out in the stool when the cord is retrieved after 4 hours. The mucus collected on the cord is then examined for the presence of parasites, including Strongyloides stercoralis, G. lamblia, Cryptosporidium spp., Microsporidia, and the eggs of Clonorchis sinensis.

 

REF:   571                OBJ:   Level: Knowledge

 

  1. A urine sample from a 26-year-old woman is examined, and an organism is observed that displays “jerky” motility. This organism is classified as a(n):
a. amebae.
b. coccidia.
c. flagellate.
d. ciliate.

 

 

ANS:  C

The organism that displays jerky motility in a wet mount is Trichomonas vaginalis, which is classified as a flagellate. The organism possesses flagella and long proteinaceous organelles used for motility and is transmitted through sexual contact.

 

REF:   571                OBJ:   Level: Application

 

  1. A modified acid-fast stain is performed on lung tissue. The most likely organism that will be observed is:
a. Naegleria fowleri.
b. Mansonella streptocerca.
c. Giardia lamblia.
d. Cryptosporidium spp.

 

 

ANS:  D

Cryptosporidium spp. can be identified in lung tissue by using a modified acid-fast stain.

 

REF:   577                OBJ:   Level: Knowledge

 

  1. A medical laboratory scientist (MLS) is examining a thin blood film from a patient suspected of having a Plasmodium infection. After examining the slide for 5 minutes and viewing approximately 100 oil immersion fields, the MLS does not observe any structures associated with Plasmodium. Which one of the following statements explains this discrepancy?
a. The stain may have been contaminated.
b. The MLS should have examined each field under high dry magnification; therefore the magnification is not correct.
c. The MLS may have missed the organism; more than 300 files should be viewed.
d. No discrepancy is present. Plasmodium spp. are not found in blood; therefore the results are accurate.

 

 

ANS:  C

An examination of the thin film in suspected Plasmodium infections usually takes 15 to 20 minutes (5 = 300 oil immersion fields) for the thin film at a magnification of 1000´.

 

REF:   576                OBJ:   Level: Problem Solving

 

  1. The PARA-TECT Cryptosporidium/Giardia test kit uses which of the following formats for detection?
a. Direct fluorescent antibody (DFA)
b. Indirect fluorescent antibody (IFA)
c. Enzyme immunoassay (EIA)
d. Probe

 

 

ANS:  A

The PARA-TECT Cryptosporidium/Giardia kit manufactured by Medical Chemical uses a DFA methodologic format.

 

REF:   580                OBJ:   Level: Knowledge

 

  1. The parasite Toxoplasma gondii is acquired via the ingestion of infected oocysts from cat feces. A diagnosis is primarily made through:
a. examination of stool.
b. examination of blood films.
c. observance of “jerky” motility.
d. serologic means.

 

 

ANS:  D

Infection caused by T. gondii, a tissue protozoon, is acquired via the ingestion of infected meat, the ingestion of oocysts from cat feces, transplacental transmission, blood transfusions, or organ transplantation. The diagnosis of toxoplasmosis is primarily made through serologic means, rather than through the identification of the organisms observed in human clinical specimens.

 

REF:   580                OBJ:   Level: Knowledge

 

Chapter 57: Liver and Lung Trematodes

Test Bank

 

MULTIPLE CHOICE

 

  1. Which second intermediate host ingests the cercariae of Clonorchis and Opisthorchis?
a. Snail
b. Crustacean
c. Copepod
d. Freshwater fish

 

 

ANS:  D

The cercariae of Clonorchis and Opisthorchis is ingested by a second intermediate host, a freshwater fish.

 

REF:   695                OBJ:   Level: Knowledge

 

  1. The adult worm of Fasciola measures 2 to 5 cm by 0.8 to 1.3 cm with a cephalic cone at the anterior end that contains the oral sucker. The drug of choice to treat Fasciola infections is:
a. praziquantel.
b. bithionol.
c. albendazole.
d. benzimidazole.

 

 

ANS:  B

The adult worm of Fasciola measures 2 to 5 cm by 0.8 to 1.3 cm with a cephalic cone at the anterior end that contains the oral sucker. The eggs measure 130 to 150 microns by 70 to 90 microns and are operculated, brownish-yellow, and unembryonated when they leave the body. The drug of choice for Fasciola is bithionol administered orally every other day for 10 to 15 doses.

 

REF:   697                OBJ:   Level: Application

 

  1. Charcot-Leyden crystals are often observed in specimens infected with which one of the following trematodes?
a. Clonorchis (Opisthorchis) sinensis
b. Opisthorchis viverrini
c. Fasciola hepatica
d. Paragonimus westermani

 

 

ANS:  D

Paragonimus eggs (see Table 57-1) may be recovered from sputum and occasionally in feces using a sedimentation concentration method. The eggs may be observed in a wet mount, with or without iodine stain (Figure 57-6). Charcot-Leyden crystals may also be observed in sputum or lung tissue specimens. Charcot-Leyden crystals are slender and pointed at both ends. The crystals normally appear colorless and stain purplish to red with trichrome.

 

REF:   697                OBJ:   Level: Knowledge

 

  1. The eggs of Paragonimus mexicanus measure approximately 80 microns by 40 microns, are unembryonated and operculated, and have thick shells that are brownish yellow. An individual with this infection has most likely traveled to which endemic area?
a. Japan
b. Africa
c. New Guinea
d. South America

 

 

ANS:  D

Paragonimus is found primarily in the Far East (China, Japan, Korea, Manchuria, Papua New Guinea, and Southeast Asia), and certain species such as P. mexicanus are found in areas of Mexico and South America. The eggs of P. westermani measure 80 to 120 microns by 45 to 60 microns, and those of P. mexicanus are approximately 80 microns by 40 microns. The eggs are unembryonated when they leave the body, operculated with opercular shoulders, thick shelled, and brownish yellow.

 

REF:   697                OBJ:   Level: Application

 

MATCHING

 

Match the fluke classification with the corresponding organism.

a. Opisthorchis viverrini
b. Fasciola spp.
c. Clonorchis (Opisthorchis) sinensis
d. Paragonimus westermani

 

 

  1. Lung fluke

 

  1. Chinese liver fluke

 

  1. Southeast Asian liver fluke

 

  1. Sheep liver fluke

 

  1. ANS:  D                    REF:   697                OBJ:   Level: Knowledge

 

  1. ANS:  C                    REF:   695                OBJ:   Level: Knowledge

 

  1. ANS:  A                    REF:   695                OBJ:   Level: Knowledge

 

  1. ANS:  B                    REF:   695                OBJ:   Level: Knowledge

Chapter 67: Antiviral Therapy, Susceptibility Testing, and Prevention

Test Bank

 

MULTIPLE CHOICE

 

  1. When performing antiviral susceptibility testing, a standard inoculum must be used. If the inoculum quantity is too large, then the isolate will appear:
a. susceptible.
b. intermediate.
c. resistant.
d. indeterminate.

 

 

ANS:  C

The final result of antiviral susceptibility testing is determined by many variables; these variables also act to hinder the standardization of antiviral susceptibility testing. Some of these variables include: (1) cell line used to grow the virus, (2) viral inoculum titer, (3) incubation time of the culture, (4) concentration range of the antiviral tested, (5) reference strains, (6) assay method, (7) endpoint criteria, (8) calculation of the endpoint, and (9) interpretation of the endpoint. Each of these factors has variables that affect the final results. For example, if the inoculum quantity is too large, then a susceptible isolate may appear resistant; if the inoculum quantity is too small, then the isolate may appear susceptible. Because of each of these variables, establishing control strains to also be tested when performing antiviral susceptibility testing is imperative.

 

REF:   851                OBJ:   Level: Knowledge

 

  1. Which type of assay uses a variety of endpoint measurements to determine whether the virus is inhibited by the antiviral drug or is demonstrating drug resistance?
a. Phenotypic
b. Genotypic
c. NA inhibition assay
d. Enzyme immunoassay

 

 

ANS:  A

Phenotypic assays use a variety of endpoint measurements to determine whether the virus is inhibited by the antiviral drug or is demonstrating drug resistance. Some of these endpoint measurements include a reduction in the number of plaques, an inhibition of viral deoxyribonucleic acid (DNA) synthesis, a reduction in the yield of a viral structural protein, and a reduction of the enzymatic activity of a functional protein.

 

REF:   852                OBJ:   Level: Knowledge

 

  1. The recombinant virus assay (RVA) uses which type of amplification methodology?
a. Transcription-mediated amplification (TMA)
b. Nucleic acid sequence-based amplification (NASBA)
c. Strand displacement amplification (SDA)
d. Reverse transcription polymerase chain reaction (RT-PCR)

 

 

ANS:  D

A phenotypic type of susceptibility testing for human immunodeficiency virus (HIV) is the RVA. This assay is used to test HIV-1 isolates to nucleoside analog reverse transcriptase (RT) inhibitors. RVA uses RT-PCR amplification of RT and protease (PR) gene coding sequences directly from the patient’s plasma.

 

REF:   853                OBJ:   Level: Knowledge

 

  1. Point mutations in the hemagglutination (HA) or neuraminidase (NA) genes during viral ribonucleoprotein (RNP) replication give rise to new strains. This mechanism is known as the antigenic:
a. drift.
b. shift.
c. re-assortment.
d. modification.

 

 

ANS:  A

The antigenic drift is caused by sequential point mutations in the HA or NA genes that occur during viral RNP replication and immune selection, which give rise to new strains; thus, the antigenic drift gives the virus the ability to re-infect nonimmune susceptible hosts each season. Another phenomenon is the antigenic shift. Influenza A solely possesses this mechanism; it involves the complete re-assortment of the segmented viral genome during a co-infection with a nonhuman animal, which results in major antigenic change and periodic worldwide outbreaks (pandemics) of a never-before-circulated type of influenza A virus. Influenza B undergoes antigenic change very slowly.

 

REF:   853–854        OBJ:   Level: Knowledge

 

  1. If a physician prescribes Tamiflu to a patient, the patient is most likely infected with which virus?
a. HIV
b. Herpes simplex virus (HSV)
c. Cytomegalovirus (CMV)
d. Influenza

 

 

ANS:  D

NA inhibitors include the medications zanamivir (Relenza) and oseltamivir (Tamiflu). Both drugs inhibit the viral protein, NA, which prevents the virus release from infected cells. The NA inhibitors are used to treat both influenza A and influenza B, although lower efficacy against influenza B has been reported when using oseltamivir. All classes of drugs are most effective when administrated within 48 hours of the onset of symptoms and work to shorten the duration of the infection, as well as reduce complications.

 

REF:   854                OBJ:   Level: Knowledge

 

  1. The only virus that has been globally eradicated is:
a. chickenpox.
b. cowpox.
c. smallpox.
d. swinepox.

 

 

ANS:  C

Global eradication of a viral disease has only occurred with smallpox. The eradication of any viral disease requires no animal reservoir, a lack of recurrent infectivity, one or few stable serotypes, and an effective vaccine.

 

REF:   856                OBJ:   Level: Knowledge

 

  1. In the 1920s, an instrument known as an “iron lung” was developed to fight breathing difficulties associated with which infection?
a. Rubella
b. Measles
c. Poliomyelitis
d. Cytomegalovirus

 

 

ANS:  C

In the late 1920s, an instrument known as the “iron lung” was developed and used to fight the breathing difficulties associated with acute flaccid paralysis—poliomyelitis. This tank respirator provided a chamber that encased the patient in an air-tight chamber and created a negative pressure around the patient’s thoracic cavity, causing air to rush into the lungs to facilitate breathing. Because of the poliomyelitis epidemics in the 1930s through the 1950s, entire polio wards that housed these “iron lungs” were established in hospitals and used to provide respiration for patients who were the most severely affected.

 

REF:   856                OBJ:   Level: Knowledge

 

  1. At the end of the 2008-2009 influenza season, 100% influenza A H3N2 and the novel 2009 influenza A H1N1 were resistant to:
a. adamantane.
b. oseltamivir.
c. Tamiflu.
d. Relenza.

 

 

ANS:  A

At the end of the 2008-2009 influenza season, 100% of influenza A H3N2 and the novel 2009 influenza A H1N1 were resistant to adamantane.

 

REF:   854                OBJ:   Level: Knowledge

 

MATCHING

 

Match the assay with its function.

a. Phenotypic assay
b. Plaque reduction assay
c. Du assay
d. Flow cytometry
e. Genotypic susceptibility assay
f. Pyrosequencing

 

 

  1. Viable cells take up neutral red dye.

 

  1. Inhibits viral DNA synthesis.

 

  1. Quantifies sequence variation.

 

  1. Quantifies the amount of viruses infected in cells.

 

  1. Inhibits viral plaque formation.

 

  1. Detects resistance genes.

 

  1. ANS:  C                    REF:   852                OBJ:   Level: Knowledge

 

  1. ANS:  A                    REF:   852                OBJ:   Level: Knowledge

 

  1. ANS:  F                    REF:   853                OBJ:   Level: Knowledge

 

  1. ANS:  D                    REF:   852                OBJ:   Level: Knowledge

 

  1. ANS:  B                    REF:   852                OBJ:   Level: Knowledge

 

  1. ANS:  E                    REF:   853                OBJ:   Level: Knowledge

 

Match the virus with the appropriate antiviral agent.

a. HSV
b. Influenza A
c. Hepatitis B virus (HBV)
d. Respiratory syncytial virus (RSV)
e. HIV

 

 

  1. Lamivudine

 

  1. Saquinavir

 

  1. Ribavirin

 

  1. Acyclovir

 

  1. Amantadine

 

  1. ANS:  C                    REF:   855                OBJ:   Level: Knowledge

 

  1. ANS:  E                    REF:   855                OBJ:   Level: Knowledge

 

  1. ANS:  D                    REF:   855                OBJ:   Level: Knowledge

 

  1. ANS:  A                    REF:   855                OBJ:   Level: Knowledge

 

  1. ANS:  B                    REF:   855                OBJ:   Level: KnowledgeChapter 75: Gastrointestinal Tract InfectionsTest Bank 

    MULTIPLE CHOICE

     

    1. The normal flora of the adult large bowel consists predominantly of:
    a. anaerobic species.
    b. Staphylococcus.
    c. Enterococcus.
    d. Enterobacteriaceae.

     

     

    ANS:  A

    The normal flora of the adult large bowel (colon) is established relatively early in life and consists predominantly of anaerobic species, including Bacteroides, Clostridium, Peptostreptococcus, Bifidobacterium, and Eubacterium. Aerobes, including Escherichia coli, other Enterobacteriaceae, enterococci, and streptococci, are outnumbered by anaerobes 1000:1.

     

    REF:   943                OBJ:   Level: Knowledge

     

    1. The transport medium that best preserves the viability of most intestinal bacterial pathogens is:
    a. buffered glycerol.
    b. rectal culture swab.
    c. Cary-Blair.
    d. Campylobacter thioglycollate broth.

     

     

    ANS:  C

    If a delay longer than 2 hours is anticipated for stool for bacterial culture, then the specimen should be placed in transport medium. Cary-Blair transport medium best preserves the viability of intestinal bacterial pathogens, including Campylobacter and Vibrio spp.

     

    REF:   954                OBJ:   Level: Knowledge

     

    1. Stool received for routine culture in most clinical laboratories in the United States should be examined for the presence of at least:
    a. Campylobacter, Salmonella, and Shigella spp.
    b. Salmonella and Shigella spp.
    c. Campylobacter and Vibrio spp.
    d. Salmonella, Shigella, and Vibrio spp.

     

     

    ANS:  A

    Stool received for routine culture in most clinical laboratories in the United States should be examined for the presence of Campylobacter, Salmonella, and Shigella spp. under all circumstances. Detection of Aeromonas and Plesiomonas spp. should be incorporated into routine stool culture procedures. The cost of performing a stool examination on every patient for all potential enteric pathogens is prohibitive. The decision as to what other bacteria are routinely cultured should take into account the incidence of gastrointestinal tract infections caused by particular etiologic agents in the area served by the laboratory. For example, if the incidence of Yersinia enterocolitica gastroenteritis is high enough in the area served by the laboratory, then this agent should also be routinely sought. Similarly, because of the increasing prevalence of disease caused by Vibrio spp. in individuals living in high-risk areas of the United States (seacoast), laboratories in these locales may routinely look for these organisms.

     

    REF:   955                OBJ:   Level: Knowledge

     

    1. Cultures for isolation of Campylobacter jejuni and Campylobacter coli should be incubated in:
    a. a capnophilic atmosphere at 42° C and examined at 24 and 48 hours.
    b. a microaerophilic atmosphere at 35° C and examined at 24 and 48 hours.
    c. regular room air at 35° C and examined at 48 and 72 hours.
    d. a microaerophilic atmosphere at 42° C and examined at 24 and 48 hours.

     

     

    ANS:  D

    Cultures for isolation of C. jejuni and C. coli should be inoculated to a selective agar containing antimicrobial agents that suppress the growth of normal flora but not of Campylobacter spp. The introduction of a blood-free, charcoal-containing medium that has more selective antibiotic components has resulted in better recovery of most enteropathogenic Campylobacter spp., compared with earlier media. Commercially produced agar plates for isolation of Campylobacters are available from several manufacturers. These plates are incubated in a microaerophilic atmosphere at 42° C and examined at 24 and 48 hours for suspicious colonies.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. Sheep blood agar serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  A

    Blood agar (tryptic soy agar with 5% sheep blood) is an excellent general supportive medium. Blood agar medium allows growth of yeast species, staphylococci, and enterococci, in addition to gram-negative bacilli. Of importance, the absence of normal gram-negative fecal flora and/or the presence of significant quantities of organisms such as Staphylococcus aureus, yeast, and Pseudomonas aeruginosa can be evaluated. Another benefit of blood agar is that it will allow oxidase testing of colonies. Several colonies that do not resemble Pseudomonas from the third or fourth quadrant should be routinely screened for the production of cytochrome oxidase. If many are present, then Aeromonas, Vibrio, or Plesiomonas spp. should be suspected.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. MacConkey agar serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  B

    The slightly selective agar should support growth of most Enterobacteriaceae, Vibrio, and other possible pathogens; MacConkey agar works well. Some laboratories use eosin-methylene blue (EMB), which is slightly more inhibitory. All lactose-negative colonies should be tested further, ensuring adequate detection of most vibrio and most pathogenic Enterobacteriaceae. Lactose-positive vibrio (V. vulnificus), pathogenic E. coli, some Aeromonas spp., and Plesiomonas spp. may not be distinctive on MacConkey agar.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. XLD agar serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  C

    The specimen should be inoculated to a moderately selective agar such as Hektoen enteric (HE) or XLD media. These media inhibit growth of most Enterobacteriaceae, allowing Salmonella and Shigella spp. to be detected.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. Campylobacter thioglycollate broth serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  D

    Campylobacter thioglycollate–enrichment broth increases the yields of positive cultures for Campylobacter spp., although it is not necessary for routine use.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. Selenite broth serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  D

    Enrichment broths are sometimes used for enhanced recovery of Salmonella, Shigella, Campylobacter, and Y. enterocolitica, although Shigella usually does not survive enrichment. Gram-negative broth (Hajna) or selenite F broth yields good recovery.

     

    REF:   956                OBJ:   Level: Knowledge

     

    1. Gram-negative broth serves which purpose when used in the bacterial fecal culture?
    a. Evaluation of general flora and predominant species
    b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
    c. Inhibition of normal flora and selection of enteric pathogens
    d. Enrichment for enteric pathogens such as Salmonella and others

     

     

    ANS:  D

    Enrichment broths are sometimes used for enhanced recovery of Salmonella, Shigella, Campylobacter, and Y. enterocolitica, although Shigella usually does not survive enrichment. Gram-negative broth (Hajna) or selenite F broth yields good recovery.

     

    REF:    956      OBJ:    Level: Knowledge