Micro Progress Flashcards
1
Q
Flocked swab:
a. Cotton
b. Gauze
c. Cotton and gauze
d. Nylon
A
d. Nylon
2
Q
The steam autoclave method of sterilization:
a. Uses 15 lbs of pressure for 15 minutes
b. Utilizes dry heat for 20 minutes
c. Produces a maximum temperature of 100ºC
d. Requires a source of ethylene oxide
A
a. Uses 15 lbs of pressure for 15 minutes
3
Q
The most important diagnostic tool in treating patients with clinical infections in the emergency department:
a. AFB stain
b. Culture
c. Gram stain
d. IMVic reaction
A
c. Gram stain
4
Q
Additional tests to be included with the IMViC reaction:
a. Bacitracin and SXT susceptibility
b. Catalase and coagulase
c. Motility and H2S
d. Oxidase and urease
A
c. Motility and H2S
5
Q
Salmonella Shigella (SS) Agar is a modification of:
a. BAP
b. CAP
c. DCA
d. EMB
A
c. DCA
Salmonella Shigella (SS) Agar is a modification of the Deoxycholate Citrate Agar.
6
Q
Cary-Blair indicator changes from red to yellow color:
a. Buffering capacity was overcomed
b. Change in the pH of the medium
c. Low temperature
d. Presence of contaminants
A
a. Buffering capacity was overcomed
7
Q
When cultured in thioglycollate broth, these organisms grow slightly below the surface where oxygen concentrations are lower than atmospheric concentrations
a. Aerotolerant anaerobes
b. Facultative anaerobes
c. Microaerophilic organisms
d. Obligate aerobes
A
c. Microaerophilic organisms
8
Q
Which one of the following specimen requests is acceptable?
a. Feces submitted for anaerobic culture
b. Foley catheter tip submitted for aerobic culture
c. Rectal swab submitted for direct smear for gonococci
d. Urine for culture of acid-fast bacilli
A
d. Urine for culture of acid-fast bacilli
9
Q
Which of the following is the most appropriate method for collecting a urine specimen from a patient with an indwelling catheter?
a. Remove the catheter, cut the tip, and submit it for culture
b. Disconnect the catheter from the bag, and collect urine from the terminal end of the catheter
c. Collect urine directly from the bag
d. Aspirate urine aseptically from the catheter tubing
A
d. Aspirate urine aseptically from the catheter tubing
10
Q
A liquid fecal specimen from a three-month-old infant is submitted for microbiological examination. In addition to culture on routine media for Salmonella and Shigella, this specimen should be routinely:
a. Examined for the presence of Entamoeba hartmanni
b.Examined for the presence of Camylobacter sp
c. Screened for the detection of enterotoxigenic Escherichia coli
d. Placed in thioglycollate broth to detect Clostridium botulinum
A
b.Examined for the presence of Camylobacter sp
11
Q
Composition of 0.5 McFarland standard:
a. 1% sulfuric acid and 2.175% barium chloride
b. 1% sulfuric acid and 1.175% barium chloride
c. 1% hydrochloric acid and 2.175% barium chloride
d. 1% hydrochloric acid and 1.175% barium chloride
A
b. 1% sulfuric acid and 1.175% barium chloride
12
Q
Standard agar depth of the Mueller-Hinton agar:
a. 1 to 2 mm
b. 3 to 5 mm
c. 6 to 8 mm
d. 7 to 9 mm
A
b. 3 to 5 mm
13
Q
Susceptibility testing performed on quality control organisms using a new media lot number yielded zone sizes that were too large for all antibiotics tested. The testing was repeated using media from a previously used lot number, and all zone sizes were acceptable. Which of the following best explains the unacceptable zone sizes?
a. The antibiotic disks were not stored with the proper desiccant
b. The depth of the media was too thick
c. The depth of the media was too thin
d. The antibiotic disks were not properly applied to the media
A
c. The depth of the media was too thin
14
Q
Quality control results for disk diffusion susceptibility tests yield the following results: aminoglycoside zones too small and penicillin zones too large. This is most likely due to the:
a. Inoculum being too heavy
b. Inoculum being too light
c. pH of Mueller-Hinton agar being too low
d. Calcium and magnesium concentration in the agar being too high
A
c. pH of Mueller-Hinton agar being too low
15
Q
In disk diffusion susceptibility testing, as an antimicrobial agent diffuses away from the disk, the concentration of antibiotic is:
a. Increased
b. Decreased
c. Unchanged
d. Inoculum dependent
A
b. Decreased
16
Q
After satisfactory performance of daily disk diffusion susceptibility quality control is documented, the frequency of quality control can be reduced to:
a. Twice a week
b. Every week
c. Every other week
d. Every month
A
b. Every week
17
Q
An outbreak of Staphylococcus aureus has occurred in a hospital nursery. In order to establish the epidemiological source of the outbreak, the most commonly used typing method is:
a. Pulsed-field gel electrophoresis
b. Serological typing
c. Coagulase testing
d. Catalase testing
A
a. Pulsed-field gel electrophoresis
18
Q
The organism most commonly associated with neonatal purulent meningitis is:
a. N. meningitidis
b. S. pneumoniae
c. S. agalactiae
d. S. pyogenes
A
c. S. agalactiae
19
Q
One of the enterotoxins produced by enterotoxigenic Escherichia coli in traveler’s diarrhea is similar to a toxin produced by:
a. Clostridium perfringens
b. Clostridium difficile
c. Vibrio cholerae
d. Yersinia enterocolitica
A
c. Vibrio cholerae
20
Q
Which of the following sets of tests best differentiates Salmonella and Citrobacter species?
a. KCN, malonate, beta-galactosidase, lysine decarboxylase
b. Dulcitol, citrate, indole, H2S production
c. Lactose, adonitol, KCN, motility
d. Lysine decarboxylase, lactose, sucrose, malonate, indole
A
a. KCN, malonate, beta-galactosidase, lysine decarboxylase
21
Q
The Oriental rat flea, Xenopsylla cheopis, can be involved in transmitting which of the following microorganisms?
a. Bartonella quintana
b. Plasmodium spp.
c. Rickettsia prowazeki
d. Yersinia pestis
A
d. Yersinia pestis
22
Q
Oxidase positive, urease negative:
a. Bordetella bronchiseptica
b. Bordetella pertussis
c. Bordetella parapertussis
d. All of these
A
b. Bordetella pertussis
23
Q
A culture from an infected dog bite on a small boy’s finger yielded a small, gram-negative coccobacillus that was smooth, raised and beta-hemolytic on blood agar. The isolate grew on MacConkey agar, forming colorless colonies. The organism was motile, catalase positive, oxidase positive, reduced nitrate, and was urease positive within 4 hours. No carbohydrates were fermented. The most likely identification of this isolate is:
a. Brucella canis
b. Yersinia pestis
c. Francisella tularensis
d. Bordetella bronchiseptica
A
d. Bordetella bronchiseptica
24
Q
While swimming in a lake near his home, a young boy cut his foot, and an infection developed. The culture grew a nonfastidious gram-negative, oxidase positive, beta hemolytic, motile bacilli that produced deoxyribonuclease. The most likely identification is:
a. Enterobacter cloacae
b. Serratia marcescens
c. Aeromonas hydrophila
d. Escherichia coli
A
c. Aeromonas hydrophila
25
A community hospital microbiology laboratory is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the country. A media that should be incorporated in the plating protocol is:
a. Colistin nalidixic acid for Listeria
b. MacConkey agar with sorbitol for Campylobacter
c. Mannitol salt agar for Enterococcus species
d. Thiosulfate citrate bile salts sucrose for Vibrio species
d. Thiosulfate citrate bile salts sucrose for Vibrio species
26
Stool specimens suspected of containing Vibrio spp. should be collected and transported only in:
a. Amies medium
b. Cary-Blair medium
c. Stuart's medium
d. Transgrow medium
b. Cary-Blair medium
27
Catalase positive, lactose negative, xylose positive:
a. Haemophilus aegypticus
b. Haemophilus ducreyi
c. Haemophilus parainfluenzae
d. Haemophilus influenzae
d. Haemophilus influenzae
28
The best procedure to differentiate Listeria monocytogenes from Corynebacterium species is:
a. Catalase
b. Motility at 25C
c. Motility at 35C
d. Gram stain
b. Motility at 25C
29
A patient has a suspected diagnosis of subacute bacterial endocarditis. His blood cultures grow non-spore-forming pleomorphic gram-positive bacilli only in the anaerobic bottle. What test(s) will give a presumptive identification of this microorganism?
a. Beta-hemolysis and oxidase
b. Catalase and spot indole
c. Esculin hydrolysis
d. Gelatin hydrolysis
b. Catalase and spot indole
30
Colonies appear shiny and mucoid because of the presence of a polysaccharide capsule:
a. Candida albicans
b. Cryptococcus neoformans
c. Malassezia furfur
d. Histoplasma capsulatum
b. Cryptococcus neoformans
31
LATEX AGGLUTINATION for cryptococcal _____ is now recommended test for Cryptococcus neoformans.
a. Polysaccharide capsule
b. Antigen
c. Antibody
d. Nucleic acids
b. Antigen
32
A mold grown at 25C exhibited delicate septate hyaline hyphae and many conidiophores extending at right angles from the hyphae. Oval, 2-5 um conidia were formed at the end of the conidiophores giving a flowerlike appearance. In some areas “sleeves” of spores could be found along the hyphae as well. A 37C culture of this organism produced small, cigar-shaped yeast cells. This organism is most likely:
a. Histoplasma capsulatum
b. Sporothrix schenckii
c. Blastomyces dermatitidis
d. Coccidioides immitis
b. Sporothrix schenckii
33
Virulence factors include aflatoxin, serine protease and aspartic acid proteinase:
a. Aspergillus spp.
b. Blastomyces dermatitidis
c. Cryptococcus neoformans
d. Histoplasma capsulatum
a. Aspergillus spp.
34
Most often, ______ are “dead-end” hosts.
a. Amphibians
b. Birds
c. Humans
d. Rodents
c. Humans
35
Delay in the processing of fluid specimens requires dilution in a viral transport medium before storage:
a. 1: 2 to 1:5
b. 1:10 to 1:20
c. 1:50 to 1:100
d. 1:100 to 1:200
a. 1: 2 to 1:5
36
The most sensitive method for the detection of β-lactamase in bacteria is by the use of:
a. Chromogenic cephalosporin
b. Penicillin
c. Oxidase
d. Chloramphenicol acetyltransferase
a. Chromogenic cephalosporin
37
According to the Kirby–Bauer standard antimicrobial susceptibility testing method, what should be done when interpreting the zone size of a motile, swarming organism such as Proteus species?
a. The swarming area should be ignored
b. The results of the disk diffusion method are invalid
c. The swarming area should be measured as the growth boundary
d. The isolate should be retested after diluting to a 0.05 McFarland standard
a. The swarming area should be ignored
38
Antimicrobial susceptibility testing of anaerobes is done by which of the following methods?
a. Broth disk elution
b. Disk agar diffusion
c. Microtube broth dilution
d. β-Lactamase testing
c. Microtube broth dilution
39
Cerebrospinal fluid (CSF) should be cultured immediately, but if delayed the specimen should be:
a. Refrigerated at 4°C to 6°C
b. Frozen at –20°C
c. Stored at room temperature for no longer than 24 hours
d. Incubated at 37°C and cultured as soon as possible
d. Incubated at 37°C and cultured as soon as possible
40
Select the method of choice for recovery of anaerobic bacteria from a deep abscess.
a. Cotton fiber swab of the abscess area
b. Skin snip of the surface tissue
c. Needle aspirate after surface decontamination
d. Swab of the scalpel used for débridement
c. Needle aspirate after surface decontamination
41
Anaerobic bacteria are routinely isolated from all of the following types of infections except:
a. Lung abscesses
b. Brain abscesses
c. Dental infections
d. Urinary tract infections
d. Urinary tract infections
42
Prereduced and vitamin K1-supplemented blood agar plates are recommended isolation media for:
a. Mycobacterium marinum and Mycobacterium avium intracellulare
b. Bacteroides, Peptostreptococcus, and Clostridium spp.
c. Proteus spp.
d. Enterococcus spp.
b. Bacteroides, Peptostreptococcus, and Clostridium spp.
43
Which of the following is the medium of choice for the selective recovery of gram-negative anaerobes?
a. Kanamycin–vancomycin (KV) agar
b. Phenylethyl alcohol (PEA) agar
c. Cycloserine–cefoxitin–fructose agar (CCFA)
d. THIO broth
a. Kanamycin–vancomycin (KV) agar
44
Methods other than packaged microsystems used to identify anaerobes include:
a. Antimicrobial susceptibility testing
b. Gas–liquid chromatography (GLC)
c. Special staining
d. Enzyme immunoassay
b. Gas–liquid chromatography (GLC)
45
Semisolid transport media such as Amies, Stuart, or Cary–Blair are suitable for the transport of swabs for culture of most pathogens except:
a. Neisseria gonorrhoeae
b. Enterobacteriaceae
c. Campylobacter fetus
d. Streptococcus pneumoniae
a. Neisseria gonorrhoeae
46
Colistin–nalidixic acid agar (CNA) is used primarily for the recovery of:
a. Neisseria species
b. Enterobacteriaceae
c. Pseudomonas aeruginosa
d. Staphylococcus aureus
d. Staphylococcus aureus
47
Toxic shock syndrome is attributed to infection with:
a. Staphylococcus epidermidis
b. Staphylococcus hominis
c. Staphylococcus aureus
d. Staphylococcus saprophyticus
c. Staphylococcus aureus
48
Which Staphylococcus species, in addition to S. aureus, also produces coagulase?
a. S. intermedius
b. S. saprophyticus
c. S. hominis
d. All of these options
a. S. intermedius
49
An isolate of Staphylococcus aureus was cultured from an ulcer obtained from the leg of a diabetic79-year-old female patient. The organism showed resistance to methicillin. Additionally, this isolate should be tested for resistance or susceptibility to:
a. Erythromycin
b. Gentamicin
c. Vancomycin
d. Kanamycin
c. Vancomycin
50
Resistance to which drug categorizes a strain of Staphylococcus aureus as methicillin-resistant Staphylococcus aureus (MRSA)?
a. Oxacillin
b. Colistin
c. Trimethoprim–sulfamethoxazole
d. Tetracycline
a. Oxacillin
51
Which test is used for the determination of inducible clindamycin resistance in staphylococci and streptococci?
a. E-test
b. D-zone test
c. A-test
d. CAMP test
b. D-zone test
52
An outbreak of Staphylococcus aureus in the nursery department prompted the Infection Control Committee to proceed with an environmental screening procedure. The best screening media to use for this purpose would be:
a. CNA agar
b. THIO broth
c. Mannitol salt agar
d. PEA agar
c. Mannitol salt agar
53
Streptococcus species exhibit which of the following properties?
a. Aerobic, oxidase positive, and catalase positive
b. Facultative anaerobe, oxidase negative, catalase negative
c. Facultative anaerobe, β-hemolytic, catalase positive
d. May be α-, β-, or γ-hemolytic, catalase positive
b. Facultative anaerobe, oxidase negative, catalase negative
54
An isolate recovered from a vaginal culture obtained from a 25-year-old female patient who is 8 months pregnant is shown to be a gram-positive cocci, catalase negative, and β-hemolytic on blood agar. Which tests are needed for further identification?
a. Optochin, bile solubility, PYR
b. Bacitracin, CAMP, PYR
c. Methicillin, PYR, trehalose
d. Coagulase, glucose, PYR
b. Bacitracin, CAMP, PYR
55
The bile solubility test causes the lysis of:
a. Streptococcus bovis colonies on a blood agar plate
b. Streptococcus pneumoniae colonies on a blood agar plate
c. Group A streptococci in broth culture
d. Group B streptococci in broth culture
b. Streptococcus pneumoniae colonies on a blood agar plate
56
Nutritionally variant streptococci (NVS) require specific thiol compounds, cysteine, or the active form of vitamin B6. Which of the following tests supplies these requirements?
a. CAMP test
b. Bacitracin susceptibility test
c. Bile solubility test
d. Staphylococcal cross-streak test
d. Staphylococcal cross-streak test
57
All of the following are appropriate when attempting to isolate N. gonorrhoeae from a genital specimen except:
a. Transport the genital swab in charcoal transport medium
b. Plate the specimen on modified Thayer–Martin (MTM) medium
c. Plate the specimen on New York City or Martin-Lewis agar
d. Culture specimens in ambient oxygen at 37°C
d. Culture specimens in ambient oxygen at 37°C
Cultures must be incubated in 3%–7% CO2 at 35°C.
58
A Gram stain of a urethral discharge from a man showing extracellular and intracellular gram-negative diplococci within segmented neutrophils is a presumptive identification for:
a. Neisseria gonorrhoeae
b. Neisseria meningitidis
c. Moraxella (Branhamella) catarrhalis
d. Neisseria lactamica
a. Neisseria gonorrhoeae
59
The β-galactosidase test aids in the identification of which Neisseria species?
a. N. lactamica
b. N. meningitidis
c. N. gonorrhoeae
d. N. flavescens
a. N. lactamica
60
Deoxycholate agar (DCA) is useful for the isolation of:
a. Enterobacteriaceae
b. Enterococcus spp.
c. Staphylococcus spp.
d. Neisseria spp.
a. Enterobacteriaceae
61
Xylose lysine deoxycholate (XLD) agar is a highly selective medium used for the recovery of which bacteria?
a. Staphylococcus spp. from normal flora
b. Yersinia spp. that do not grow on Hektoen agar
c. Enterobacteriaceae from gastrointestinal specimens
d. Streptococcus spp. from stool cultures
c. Enterobacteriaceae from gastrointestinal specimens
62
The Voges–Proskauer (VP) test detects which end product of glucose fermentation?
a. Acetoin
b. Nitrite
c. Acetic acid
d. Hydrogen sulfide
a. Acetoin
63
At which pH does the methyl red (MR) test become positive?
a. 7.0
b. 6.5
c. 6.0
d. 4.5
d. 4.5
64
The ortho-nitrophenyl-β-galactopyranoside(ONPG) test is most useful when differentiating:
a. Salmonella spp. from Pseudomonas spp.
b. Shigella spp. from some strains of Escherichia coli
c. Klebsiella spp. from Enterobacter spp.
d. Proteus vulgaris from Salmonella spp.
b. Shigella spp. from some strains of Escherichia coli
65
In the test for urease production, ammonia reacts to form which product?
a. Ammonium citrate
b. Ammonium carbonate
c. Ammonium oxalate
d. Ammonium nitrate
b. Ammonium carbonate
66
Which of the following reagents is added to detect the production of indole?
a. p-Dimethylaminobenzaldehyde
b. Bromcresol purple
c. Methyl red
d. Cytochrome oxidase
a. p-Dimethylaminobenzaldehyde
67
Decarboxylation of the amino acids lysine, ornithine, and arginine results in the formation of:
a. Ammonia
b. Urea
c. CO2
d. Amines
d. Amines
68
Putrescine is an alkaline amine product of which bacterial enzyme?
a. Arginine decarboxylase
b. Phenylalanine deaminase
c. Ornithine decarboxylase
d. Lysine decarboxylase
c. Ornithine decarboxylase
69
Which genera are positive for phenylalanine deaminase
a. Enterobacter, Escherichia, and Salmonella
b. Morganella, Providencia, and Proteus
c. Klebsiella and Enterobacter
d. Proteus, Escherichia, and Shigella
b. Morganella, Providencia, and Proteus
70
Biochemically, the Enterobacteriaceae are gram-negative rods that:
a. Ferment glucose, reduce nitrate to nitrite, and are oxidase negative
b. Ferment glucose, produce indophenol oxidase, and form gas
c. Ferment lactose and reduce nitrite to nitrogen gas
d. Ferment lactose and produce indophenol oxidase
a. Ferment glucose, reduce nitrate to nitrite, and are oxidase negative
71
Care must be taken when identifying biochemical isolates of Shigella because serological cross-reactions occur with:
a. E. coli
b. Salmonella spp.
c. Pseudomonas spp.
d. Proteus spp.
a. E. coli
72
Which of the following tests best differentiates Shigella species from E. coli?
a. Hydrogen sulfide, VP, citrate, and urease
b. Lactose, indole, ONPG, and motility
c. Hydrogen sulfide, MR, citrate, and urease
d. Gas, citrate, and VP
b. Lactose, indole, ONPG, and motility
73
Fever, abdominal cramping, watery stools, and fluid and electrolyte loss preceded by bloody stools 2–3 days before is characteristic of shigellosis but may also result from infection with:
a. Campylobacter spp.
b. Salmonella spp.
c. Proteus spp.
d. Yersinia spp.
a. Campylobacter spp.
74
A gram-negative rod is recovered from a catheterized urine sample from a nursing home patient. The lactose-negative isolate tested positive for indole, urease, ornithine decarboxylase, and phenylalanine deaminase and negative for H2S.The most probable identification is:
a. Edwardsiella spp.
b. Morganella spp.
c. Ewingella spp.
d. Shigella spp.
b. Morganella spp.
75
The Shiga-like toxin (verotoxin) is produced mainly by which Enterobacteriaceae?
a. Klebsiella pneumoniae
b. E. coli
c. Salmonella typhimurium
d. Enterobacter cloacae
b. E. coli
76
Following a 2-week camping trip to the Southwest (US), a 65-year-old male patient was hospitalized with a high fever and an inflammatory swelling of the axilla and groin lymph nodes. Several blood cultures were obtained, resulting in growth of gram-negative rods resembling “closed safety pins.” The organism grew on MacConkey’s agar showing non–lactose-fermenting colonies. Testing demonstrated a nonmotile rod that was biochemically inert. What is the most likely identification?
a. Yersinia pestis
b. Klebsiella pneumoniae
c. Proteus vulgaris
d. Morganella morganii
a. Yersinia pestis
77
The majority of clinical laboratories with a microbiology department should have the capability of serotyping which pathogenic Enterobacteriaceae?
a. Yersinia enterocolitica, Shigella spp.
b. E. coli O157:H7, Salmonella spp., Shigella spp.
c. Yersinia pestis, Salmonella spp.
d. Edwardsiella spp., Salmonella spp.
b. E. coli O157:H7, Salmonella spp., Shigella spp.
78
The drugs of choice for treatment of infections with Enterobacteriaceae are:
a. Aminoglycosides, trimethoprim–sulfamethoxazole, third-generation cephalosporins
b. Ampicillin and nalidixic acid
c. Streptomycin and isoniazid
d. Chloramphenicol, ampicillin, and colistin
a. Aminoglycosides, trimethoprim–sulfamethoxazole, third-generation cephalosporins
79
Which isolates of the Enterobacteriaceae family most commonly produce extended-spectrumβ-lactamase (ESBL)?
a. E. coli and Klebsiella pneumoniae
b. Yersinia enterocolitica and Yersinia pestis
c. Morganella morganii and Proteus vulgaris
d. Salmonella typhi and Shigella sonnei
a. E. coli and Klebsiella pneumoniae
80
Which test group best differentiates Acinetobacter baumannii from P. aeruginosa?
a. Oxidase, motility, NO3 reduction
b. MacConkey growth, 37°C growth, catalase
c. Blood agar growth, oxidase, catalase
d. Oxidase, TSI, MacConkey growth
a. Oxidase, motility, NO3 reduction
81
Which organism is associated with immunodeficiency syndromes and melioidosis (a glanders-like disease in Southeast Asia and northern Australia)?
a. Pseudomonas aeruginosa
b. Pseudomonas stutzeri
c. Pseudomonas putida
d. Burkholderia pseudomallei
d. Burkholderia pseudomallei
82
Which biochemical tests are needed to differentiate Burkholderia cepacia from S. maltophilia?
a. Pigment on blood agar, oxidase, DNase
b. Pigment on MacConkey agar, flagellar stain, motility
c. Glucose, maltose, lysine decarboxylase
d. TSI, motility, oxidase
a. Pigment on blood agar, oxidase, DNase
83
Alcaligenes faecalis (formerly A. odorans) is distinguished from Bordetella bronchiseptica with which test?
a. Urease (rapid)
b. Oxidase
c. Growth on MacConkey agar
d. Motility
a. Urease (rapid)
84
Cetrimide agar is used as a selective isolation agar for which organism?
a. Acinetobacter spp.
b. Pseudomonas aeruginosa
c. Moraxella spp.
d. Stenotrophomonas maltophilia
b. Pseudomonas aeruginosa
85
Which of the listed Pseudomonas spp. is associated with the following virulence factors: exotoxin A, endotoxins, proteolytic enzymes, antimicrobial resistance, and production of alginate?
a. P. fluorescens
b. P. putida
c. P. stutzeri
d. P. aeruginosa
d. P. aeruginosa
86
Select the media of choice for recovery of Vibrio cholerae from a stool specimen.
a. MacConkey agar and thioglycollate media
b. Thiosulfate–citrate–bile–sucrose (TCBS) agar and alkaline peptone water (APW) broth
c. Blood agar and selenite-F (SEL) broth
d. CNA agar
b. Thiosulfate–citrate–bile–sucrose (TCBS) agar and alkaline peptone water (APW) broth
87
Abdominal pain, fever, vomiting, and nausea prompted an elderly male to seek medical attention. A watery stool specimen producing no fecal leukocytes or erythrocytes was cultured and grew a predominance of gram-negative fermentative bacilli. The colonies were beta-hemolytic on blood agar and cream colored on MacConkey agar. The colonies were both oxidase and catalase positive. What is the most likely identification?
a. Aeromonas hydrophilia
b. Escherichia coli
c. Salmonella spp.
d. Shigella spp.
a. Aeromonas hydrophilia
The oxidase positive test result rules out the members of the Enterobacteriaceae family.
88
Several attendees of a medical conference in the Gulf coast area became ill after frequenting a seafood restaurant. A presumptive identification of Vibrio cholera was made after stool specimens from several subjects grew clear colonies on MacConkey agar and yellow colonies on TCBS agar. Which key tests would help eliminate Aeromonas and Plesiomonas spp.?
a. Mannitol fermentation, Na+ requirement
b. Oxidase, motility
c. Oxidase, nitrate
d. Hemolysis on blood agar, catalase
a. Mannitol fermentation, Na+ requirement
89
Which of the following tests should be done first in order to differentiate Aeromonas spp. from the Enterobacteriaceae?
a. Urease
b. OF glucose
c. Oxidase
d. Catalase
c. Oxidase
90
Which atmospheric condition is needed to recover Campylobacter spp. from specimens inoculated onto a Campy-selective agar at 35°C–37°C and 42°C?
a. 5% O2, 10% CO2, and 85% N2
b. 20% O2, 10% CO2, and 70% N2
c. 20% O2, 20% CO2, and 60% N2
d. 20% O2, 5% CO2, and 75% N2
a. 5% O2, 10% CO2, and 85% N2
91
Which group of tests best differentiates Helicobacter pylori from C. jejuni?
a. Catalase, oxidase, and Gram stain
b. Catalase, oxidase, and nalidixic acid sensitivity
c. Catalase, oxidase, and cephalothin sensitivity
d. Urease, nitrate, and hippurate hydrolysis
d. Urease, nitrate, and hippurate hydrolysis
92
Smooth gray colonies showing no hemolysis are recovered from an infected cat scratch on blood and chocolate agar but fail to grow on MacConkey agar. The organisms are gram-negative pleomorphic rods that are both catalase and oxidase positive and strongly indole positive. The most likely organism is:
a. Capnocytophaga spp.
b. Pasteurella spp.
c. Proteus spp.
d. Pseudomonas spp
b. Pasteurella spp.
93
A 29-year-old male who often hunted rabbits and spent a lot of time in the woods was admitted to the hospital with skin ulcers on his upper extremities. At 48 hours, a small coccobacillus was recovered from the aerobic blood culture bottle only. The organism stained poorly with Gram stain, but did stain with acridine orange. Cultures taken from the ulcers did not grow on primary media. What is the most likely identification?
a. Pseudomonas aeruginosa
b. Pseudomonas fluorescens
c. Chryseobacterium spp.
d. Francisella tularensis
d. Francisella tularensis
94
An elderly woman who cared for several domestic cats was hospitalized with suspected cat-scratch disease (CSD). Blood cultures appeared negative, but a small, slightly curved pleomorphic gram-negative bacillus grew on BHI agar (brain, heart infusion agar with 5% horse or rabbit blood). What is the most likely identification?
a. Bartonella spp.
b. Brucella spp.
c. Kingella spp.
d. Haemophilus spp
a. Bartonella spp.
95
A neonate was readmitted to the hospital with a diagnosis of meningitis. The CSF revealed gram-negative straight rods. At 24 hours, the organism grew on 5% sheep blood and chocolate agars displaying a yellow pigment. On MacConkey agar, it appeared as a non–lactose fermenter. Colonies were oxidase, DNase, and gelatinase positive, and oxidized glucose and mannitol. What is the most likely identification?
a. Haemophilus influenza
b. Chryseobacterium meningosepticum
c. Stenotrophomonas maltophilia
d. Acinetobacter baumannii
b. Chryseobacterium meningosepticum
96
A 46-year-old dog warden was admitted to the hospital with several puncture bite wounds encountered while wrangling with a stray dog. Culture at 48 hours produced small yellow colonies on 5% sheep blood and chocolate agars in10% CO2, but no growth on MacConkey agar. Gram stain showed gram-negative curved, fusiform rods. Colonies were oxidase and catalase positive. What is the most likely identification?
a. Capnocytophaga canimorsus
b. Francisella tularensis
c. Legionella pneumophila
d. Pseudomonas aeruginosa
a. Capnocytophaga canimorsus
97
A suspected case of Legionnaires’ disease was noted on the request form for a culture and sensitivity ordered on a sputum sample. The patient was a 70-year-old male who presented with a positive serological test for Legionella spp. What is the most efficient way to confirm the infection using the submitted sample?
a. Culture the sputum on MacConkey agar
b. Gram stain of the sputum
c. Acid-fast staining
d. Direct immunofluorescent microscopy
d. Direct immunofluorescent microscopy
98
Which of the following organisms will display lipase activity on egg yolk agar?
a. Clostridium botulinum
b. Clostridium sporogenes
c. Clostridium novyi (A)
d. All of these options
d. All of these options
99
Identification of Clostridium tetani is based upon:
a. Gram stain of the wound site
b. Anaerobic culture of the wound site
c. Blood culture results
d. Clinical findings
d. Clinical findings
100
Cycloserine–cefoxitin-fructose agar (CCFA) is used for the recovery of:
a. Yersinia enterocolitica
b. Yersinia intermedia
c. Clostridium perfringens
d. Clostridium difficile
d. Clostridium difficile
101
The gram-positive non–spore-forming anaerobic rods most frequently recovered from blood cultures as a contaminant are:
a. Propionibacterium acnes
b. Clostridium perfringens
c. Staphylococcus intermedius
d. Veillonella parvula
a. Propionibacterium acnes
102
A flexible calcium alginate nasopharyngeal swab is the collection device of choice for recovery of:
a. Staphylococcus aureus
b. Streptococcus pneumoniae
c. Corynebacterium diphtheriae
d. Bacteroides fragilis
c. Corynebacterium diphtheriae
103
Acid-fast staining of a smear prepared from digested sputum showed slender, slightly curved, beaded, red mycobacterial rods. Growth on Middlebrook 7H10 slants produced buff-colored microcolonies with a serpentine pattern after 14 days at 37°C. Niacin and nitrate reduction tests were positive. What is the most probable presumptive identification?
a. Mycobacterium tuberculosis
b. Mycobacterium ulcerans
c. Mycobacterium kansasii
d. Mycobacterium avium–intracellulare complex
a. Mycobacterium tuberculosis
104
Individuals showing a positive purified protein derivative (PPD) skin test for M. tuberculosis are usually:
a. Infective
b. Symptomatic of pulmonary disease
c. Latently infected
d. Falsely positive
c. Latently infected
105
Which mycobacterium is associated with Crohn’s disease?
a. M. marinum
b. M. paratuberculosis
c. M. avium
d. M. gordonae
b. M. paratuberculosis
106
Routine laboratory testing for Treponema pallidum involves:
a. Culturing
b. Serological analysis
c. Acid-fast staining
d. Gram staining
b. Serological analysis
107
Which organism typically produces “fried-egg” colonies on agar within 1–5 days of culture from a genital specimen?
a. Mycoplasma hominis
b. Borrelia burgdorferi
c. Leptospira interrogans
d. Treponema pallidum
a. Mycoplasma hominis
108
Which procedure is appropriate for culture of genital specimens in order to recover Chlamydia spp.?
a. Inoculate cycloheximide-treated McCoy cells
b. Plate onto blood and chocolate agar
c. Inoculate into thioglycollate (THIO) broth
d. Plate onto modified Thayer–Martin agar within 24 hours
a. Inoculate cycloheximide-treated McCoy cells
109
Which of the following organisms are transmitted to animals and humans after a tick bite?
a. Leptospira
b. Chlamydia and Mycoplasma spp.
c. Neisseria sicca
d. Ehrlichia and Anaplasma spp.
d. Ehrlichia and Anaplasma spp.
110
What is the first step to be performed in the identification of an unknown yeast isolate?
a. Gram stain smear
b. India ink stain
c. Catalase test
d. Germ tube test
d. Germ tube test
111
The Hair Baiting Test is used to differentiate which two species of Trichophyton that produce red colonies on Sabouraud agar plates?
a. T. mentagrophytes and T. rubrum
b. T. tonsurans and T. schoenleinii
c. T. tonsurans and T. violaceum
d. T. verrucosum and T. rubrum
a. T. mentagrophytes and T. rubrum
112
An India ink test was performed on CSF from an HIV-infected male patient. Many encapsulated yeast cells were seen in the centrifuged sample. Further testing revealed a positive urease test and growth of brown colonies on niger-seed agar. The diagnosis of meningitis was caused by which yeast?
a. Candida albicans
b. Cryptococcus neoformans
c. Cryptococcus laurentii
d. Candida tropicalis
b. Cryptococcus neoformans
113
After a vacation to the Southwestern United States, a midwesterner complained of flulike symptoms with fever, chills, nonproductive cough, and chest pain. Microscopic exam of sputum, cleared with KOH, revealed large, thick-walled spherules containing endospores. Upon culture, the mold phase showed septate hyphae and alternating barrel-shaped arthroconidia. Which organism is most likely the cause of thispneumonia?
a. Coccidioides immitis
b. Histoplasma capsulatum
c. Paracoccidioides brasiliensis
d. Penicillium marneffei
a. Coccidioides immitis
114
Specimens for virus culture should be transported in media containing:
a. Antibiotics and 5% sheep blood
b. Saline and 5% sheep blood
c. 22% bovine albumin
d. Antibiotics and nutrient
d. Antibiotics and nutrient
115
Which virus belonging to the Reoviridae group causes gastroenteritis in infants and young children but an asymptomatic infection in adults?
a. Coxsackie B virus
b. Rotavirus
c. Respiratory syncytial virus
d. Rhabdovirus
b. Rotavirus
116
A 40-year-old female experienced a respiratory infection after returning home from a visit to her homeland of China. A rapid onset of pneumonia in the lower respiratory area prompted the physician to place her in isolation. She was diagnosed presumptively with severe acute respiratory syndrome (SARS) and placed on a respirator. What type of testing should be done next to diagnose this disease?
a. Molecular technique and cell culture
b. Latex agglutination test
c. Blood culture
d. Complement fixation
a. Molecular technique and cell culture
