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MLT ASCP BOC MICRO

MLT ASCP BOC MICROBIOLOGY

QuestionAnswer
1) Proper media for culture of a urethral discharge from a man include: a. sheep blood and phenylethyl alcohol agars b. eosin methylene blue and sheep blood agars d. chocolate agar and modified Thayer Martin agar d. chocolate agar and modified Thayer Martin agar
) A sheep blood agar plate inoculated with 0.001 mL of urine grows 70 colonies of Staphylococcus aureus. How many colony forming units per mL of urine should be reported: a. 70 b. 700 c. 7000 d. 70000 d. 70000 d (When 0.001 mL of urine is plated, the growth of one colony is equivalent to 1000 CPU/mL. Thus 70 colonies is 70,000 CPU/mL.)
3) The lowest concentration of antibiotic that inhibits growth of a test organism is the : a. minimum inhibitory concentration b. serum inhibitory concentration c. minimum bactericidal titer d. minimum inhibitory titer a. minimum inhibitory concentration a (The MIC is a basic laboratory measurement of the activity of an antibiotic against an organism
5) 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 minimum temp of 100 C d. requires a source of ethylene oxide a. uses 15 lbs. of pressure for 15 minutes a (The traditional gravity displacement steam sterilization cycle is 121 C for 15 minutes at 15 pounds per square inch. Ethylene oxide is an alternative sterilization method.
6) The expected colony count in a suprapubic urine from a healthy individual is: a. 0 CFU/mL b. 100 CFU/mL c. 1,000 CFU/mL d. 100,000 CFU/mL a. 0 CFU/mL a (Urine in the bladder is normally sterile. Suprapubic aspiration removes urine directly from the bladder and yields a specimen free of urethral contamination.)
7) An aspirate of a deep wound was plated on blood agar plates and incubated aerobically and anaerobically. At 24 hrs. there was growth on both plates. This indicates that the organism is a: a. nonfermenter b. obligate anaerobe d. facultative anaerobe d. facultative anaerobe
9) A penicillin resistant Neisseria gonorrhoeae produces: a. alpha-hemolysin b. beta-lactamase c. enterotoxin d. coagulase b. beta-lactamase he production of beta-lactamase [penicillinase] breaks open the beta lactam ring of penicillin, destroying its activity. Thus, N. gonorrhoeae that produce beta lactamase are resistant to penicillin.)
10) Which selective medium is used for the isolation of gram-positive microorganisms? a. Columbia CNA with 5% sheep blood b. trypticase soy agar with 5% sheep blood c. eosin methylene blue d. modified Thayer-Martin a. Columbia CNA with 5% sheep blood
11) The most sensitive substrate for the detection of beta-lactamases is: a. penicillin b. ampicillin c. cefoxitin d. nitrocefin d. nitrocefin (The chromogenic cephalosporin test using nitrocefin is the most sensitive and specific test for detection of beta lactamase
13) An Enterococcus isolated from multiple blood cultures in a patient with endocarditis should be: a. screened for high level aminoglycoside resistance b. checked for tolerance c. assayed for serum antimicrobial activity a. screened for high level aminoglycoside resistance a (Systemic enterococcal infections, such as endocarditis, are commonly treated with a cell-wall-active agent and an aminoglycoside.
14) In the Kirby-Bauer disk diffusion susceptibility test, which variable is critical when testing Pseudomonas species for antibiotic susceptibility to aminoglycosides? a. incubation temp b. duration of incubation c. cation content of media d. depth o c. cation content of media A cation concentration that is too high results in smaller zone sizes, and a concentration that is too low increases zone sizes.)
15) The procedure that assures the most accurate detection of mecA-mediated oxacillin resistance in routine broth microdilution susceptibility testing against S aureus is: a. addition of 4% NaCl b. incubation at 37 d. use of cefoxitin for testing d. use of cefoxitin for testing d (Cefoxitin is used as a surrogate for mecA-mediated oxacillin resistance in S aureus.
17) 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 we c. the depth of the media was too thin If the depth of the media is < 4 mm, this may be associated with excessively large zones and false-positive susceptibility results
18) 3 sets of blood cultures were obtained from an adult patient with fever and suspected endocarditis. The aerobic bottle of one set had growth of Staphylococcus epidermidis at 5 days of incubation. This indicates that: b. the organism is most likely a contaminant b (Coagulase-negative staphylococci are commonly associated with contaminated blood cultures; however, they are also increasing as a cause of true bacteremia
19) In order to isolate Campylobacter coli/jejuni the fecal specimen should be: a. inoculated onto selective plating media and incubated in reduced oxygen with added CO2 at 42 C
21) Which type of microscope would be most useful in examining viruses and the structure of microbial cells? a. electron b. phase-contrast c. dark-field d. bright-field a. electron Electron microscopy is used to visualize viruses and the internal structure of microorganisms.)
22) 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 b. every week
23) In disk diffusion susceptibility testing, as a antimicrobial agent diffuses away from the disk, the concentration antibiotic is: a. increased b. decreased c. unchanged d. inoculum dependent b. decreased
24) The most common cause for failure of a Gas Pak anaerobic jar to establish an adequate environment for anaerobic incubation is: d. catalysts that have become inactivated after repeated use d (The 2 most common causes of failure of the Gas Pak system is a defective gasket in the jar lid that allows escape of gas from inside the jar and inactivated catalyst pellets.)
26) Which 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 d. urine for culture of acid-fast bacilli d (Urine is an appropriate specimen for the detection of renal tuberculosis. Since feces contain anaerobic organisms as part of the indigenous flora, it is an unacceptable specimen for anaerobic culture.
27) Which of the following groups of specimens would be acceptable for anaerobic culture? a. vaginal, eye b. ear, leg tissue c. pleural fluid, brain abscess d. urine, sputum c. pleural fluid, brain abscess c (Materials collected from sites not harboring indigenous flora [sterile body fluids, abscess exudate and tissue] should be cultured for anaerobic bacteria.
28) A liquid fecal specimen from a 3 month old infant is submitted for microbiological exam. In addition to culture on routine media for Salmonella and Shigella, this specimen should be routinely: b. examined for the presence of Campylobacter sp. b (Campylobacter continues to be the most common enteric pathogen isolated from patients with diarrhea.
29) Cerebrospinal fluid from a febrile 25 yr. old man with possible meningitis is rushed to the lab for a stat gram stain and culture. While performing the gram stain, the tech accidently spills most of the specimen. The smear shows many neutrophils and n c. chocolate agar plate c (Enriched media such as chocolate agar has no inhibitory effects on bacterial growth and contains additional nutrients that support the growth of fastidious organisms such as H influenzae and Neisseria.)
31) Which of the following is the most appropriate specimen source and primary media battery? a. endocervical - chocolate, Martin Lewis a (Chocolate agar and chocolate agar-based selective media [Martin Lewis] are routinely used for the recovery of Neisseria gonorrhoeae from genital specimens
32) Which of the following in the most appropriate organism and media combination? d. Yersinia enterocolitica - cefsulodin-irgasan-novobiocin (CIN agar is a selective and differential medium for the isolation and differentiation of Y enterocolitica
34) Upon review of a sputum Gram stain, the technician notes that the nuclei of all of the neutrophils present in the smear are staining dark blue. The best explanation for this finding is: a. the slide was inadequately decolorized with acetone/alcohol a. the slide was inadequately decolorized with acetone/alcohol Inadequate decolorization with acetone/alcohol results in a smear in which host cells [neutrophils and squamous cells], as well as bacteria, all appear blue.)
35) When performing a Kovac indole test, the substrate must contain: a. indole b. tryptophan c. ornithine d. paradimethylaninobenzaldehyde b. tryptophan b (The indole test is used for determining an organism's ability to produce indole from deamination of tryptophan by tryptophanase.)
36) The ONPG test allows organisms to be classified as a lactose fermenter by testing for which of the following? a. permease b. beta-galactosidase c. beta-lactamase d. phosphatase c (Differential media contain b. beta-galactosidase
39) A medium that aids in the presumptive identification of organisms based on their appearance on the medium is called: a. enriched b. selective c. differential d. specialized c. differential (Differential media contain compounds, often carbohydrates, that provide a presumptive identification based on colony color or a precipitate around the colony.
42) Which of the following methods is inadequate for the detection of vancomycin-intermediate S aureus? a. broth macrodilution b. agar dilution c. gradient diffusion d. disk diffusion d. disk diffusion
43) In a disk diffusion susceptibility test, which of the following can result if disks are placed on the inoculated media and left at room temp for an hour before incubation? c. zones of larger diameter would result c (A delay of more than 15 minutes between placing the disks on an inoculated plate and incubation permits excess prediffusion of the antimicrobial agent from the disk. This would result in a larger than expected
45) First generation cephalosporins can be adequately represented by: a. cefotetan b. ceftriaxone c. cephalothin d. cefoxitin c. cephalothin
46) An antibiotic that inhibits cell wall synthesis is: a. chloramphenicol b. penicillin c. sulfamethoxazole d. colistin b. penicillin b (Penicillin inhibits penicillin binding proteins that are essential to peptidoglycan [cell wall] synthesis
47) Which of the following organisms does not require susceptibility testing to the antimicrobial indicated when isolated from a clinically significant source? c. Streptococcus pyogenes - penicillin
49) Which of the following must be incubated in a microaerophilic environment for optimal recovery of the organism? a. Campylobacter jejuni b. Escheria Coli c. Pseudomonas aeruginosa d. Proteus mirabilis a. Campylobacter jejuni
51) Vibrio parahaemolyticus can be isolated best from feces on: a. eosin methylene blue agar b. Hektoen Shigella agar c. Salmonella Shigella agar d. thiosulfate citrate bile salts agar d. thiosulfate citrate bile salts agar d (TCBS is a highly selective and differential medium for the recovery of most Vibrio species including V parahaemolyticus.
52) Which of the following media can be used to culture Campylobacter jejuni? a. Skirrow medium b. CIN agar c. anaerobic CNA agar d. bismuth sulfite a. Skirrow medium a (Skirrow medium is an enriched selective blood agar medium used for the isolation of Campylobacter from specimens with mixed flora
53) Tests for beta-lactamase production in Haemophilus influenzae: a. are not commercially available b. include tests that measure a change to an alkaline pH c. should be performed on all blood and CSF isolates c. should be performed on all blood and CSF isolates
54) Media used to support growth of Legionella pneumophila should contain which of the following? a. X and V factors b. hemin and Vitamin K c. charcoal and yeast extract d. dextrose and laked blood c. charcoal and yeast extract c (Buffered charcoal yeast extract medium is a specialized enrichment medium for the isolation of Legionella. The nutritive base includes yeast extract. Charcoal is added to the medium as a detoxifying agent.)
55) The best medium for culture of Bordetella pertussis is: a. Regan-Lowe agar b. cystine blood agar c. Martin Lewis agar d. Ashdown agar a. Regan-Lowe agar (Regan-Lowe agar is an enriched and selective medium for the isolation of B pertussis.
56) The best medium for culture of Francisella tularensis is: a. Bordet-Gengou medium b. cystine glucose blood agar c. Loeffler medium d. charcoal selective medium b. cystine glucose blood agar Cysteine blood glucose agar is an enriched medium with beef heart infusion, peptones, glucose and rabbit blood. It also includes cystine, which is required by F tularensis for growth.)
58) When processing throat swabs for a group A streptococcus culture, the medium of choice is: a. sheep blood agar b. rabbit blood agar c. human blood agar d. horse blood agar a. sheep blood agar a (Sheep blood agar is preferred because clear-cut patterns of hemolysis are obtained.
59) The ability to detect oxacillin resistant staphylococcus aureus may be enhanced by: c. using Mueller-Hinton broth with 2% NaCl
60) The optimal wound specimen for cultures of anaerobic organisms should be: c. a syringe filled with pus, obtained before administration of antibiotics
61) A 21 yr. old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be: b. rejected as unacceptable Anaerobic bacteria do not cause pharyngitis. The most common cause of pharyngitis is Streptococcus pyogenes.
63) An antibiotic used to suppress or kill contaminating fungi in media is: a. penicillin b. cycloheximide c. streptomycin d. amphotericin B b. cycloheximide
64) Production of beta-lactamase is inducible in which of the following: a. Haemophilus influenzae b. Staphylococcus aureus c. Corynebacterium diphtheriae d. Streptococcus pyogenes b. Staphylococcus aureus S aureus produces beta-lactamase only after exposure to an inducing agent [such as penicillin].
70) When using a control stain of Staphylococcus aureus, the tech notice that the zone around the oxacillin disk is too small. Which of the following is the most likely explanation? d. use of outdated oxacillin disks d (Deterioration of the antimicrobial agent in the disk will cause the zone sizes to be too small [falsely resistant].
72) Which of the following organisms may be mistaken for Neisseria gonorrhoeae in Gram stained smears of uterine cervix exudates? a. Lactobacillus species b. Streptococcus agalactiae c. Pseudomonas aeruginosa d. Moraxella osloensis d. Moraxella osloensis d (Moraxella osloensis is a gram-negative coccobacillus that is often plump and occurs in pairs and demonstrates a morphology similar to Neisseria.
75) Which of the following antimicrobials would be inappropriate to report on an E coli isolated from a wound culture? a. gentamicin b. ampicillin c. cefazolin d. nitrofurantoin d. nitrofurantoin d (Certain antimicrobials, such as nitrofurantoin and norfloxacin, are used only or primarily to treat urinary tract infections. These agents should not be reported for pathogens recovered from other sites of infection.)
78) Which of the following combinations is useful for confirming the presence of extended spectrum beta-lactamases of E coli? a. ampicillin + cefepime b. cefoxitin + penicillin c. ceftrazidime + clavulanic acid d. cefpodoxime + cefotaxime c. ceftrazidime + clavulanic acid c (Extended spectrum beta lactamases [ESBL] are inhibited by clavulanic acid. Confirmatory tests for the presence of ESBL are based on the enhanced activity of a beta-lactam antibiotic, usually cefotaxime or ceftazidime,
80) Which of the following is most important variable in the recovery of organisms in patients with bacteremia? b. the volume of blood cultured b (The volume of blood collected is the single most important variable in the recovery of organisms in patients with bloodstream infections.
84) A vaginal/rectal swab is collected from a pregnant patient to screen for group B streptococcus colonization. What is the best medium to use for specimen inoculation? a. blood agar b. LIM broth c. CNA agar d. thioglycollate broth b. LIM broth
87) To quality control the autoclave, a vial of Bacillus stearothermophilus is autoclaved and should they be: a. inoculated to blood agar b. incubated at 37 C c. inoculated to chocolate agar d. incubated at 56 C d. incubated at 56 C
88) In a quality control procedure on a new batch of Mueller-Hinton plates using a stock culture of staphylococcus aureus, all the disk zone sizes are too small. The most likely reason for this is that the: c. bacterial suspension was not diluted to the proper concentration
89) Which of the following combinations of organisms would be appropriate as controls to test the functions listed? d. indole - negative Escherichia coli and Proteus mirabilis d (Of the combinations listed, the use of E coli and Proteus mirabilis will produce a positive and negative result for indole, respectively
90) A urine Gram stain shows gram-positive cocci in clusters. The organism tested catalase positive. To speciate this organism from culture, the technician should perform a coagulase test and a/an: b. novobiocin susceptibility b (The organism in this urine culture is a Staphylococcus species. Coagulase will differentiate S aureus from coagulase-negative staphylococci [CNS] and novobiocin susceptibility will differentiate S saprophyticus from other
91) The Gram stain from a blood culture shows gram-positive cocci in chains. No growth occurs on blood agar plates incubated both aerobically and anaerobically. Additional testing should be done to detect the presence of: c. Abiotrophia defectiva c (Nutritionally deficient streptococci such as Abiotrophia do not grow on sheep blood agar without the addition of cysteine or proximity to S aureus colonies.)
92) Viridans streptococci can be differentiated from Streptococcus pneumoniae by: a. alpha hemolysis b. morphology c. catalase reaction d. bile solubility d. bile solubility d (Bile solubility testing of alpha-hemolytic streptococci differentiates S pneumoniae [soluble] from other alpha-hemolytic streptococci, such as viridans streptococci [insoluble].)
93) A reliable test for distinguishing Staphylococcus aureus from other staphylococci is: a. oxidase b. coagulase c. catalase d. optochin susceptibility b. coagulase b (Coagulase is the biochemical test used to distinguish S aureus [positive] from coagulase-negative staphylococci [negative].)
94) The optochin (ethylhydrocupreine hydrochloride) disk is used for the identification of: a. Haemophilus influenzae b. group A beta-hemolytic streptococci c. Streptococcus pneumoniae d. alpha-hemolytic streptococci c. Streptococcus pneumoniae c (Optochin susceptibility is used to differentiate S pneumoniae, which are susceptible, from other alpha-hemolytic streptococci, which are resistant.)
95) In the optochin (ethylhydrocupreine hydrochloride) susceptibility test, if there is a zone of inhibition of 19-30 mm surrounding the disk following overnight incubation at 37 C, the colony most likely consists of: c. pneumococci c (Optochin susceptibility is used to differentiate S pneumoniae, which are susceptible from other alpha-hemolytic streptococci, which are resistant.)
96) Which 2 diseases are usually preceded by infection with beta-hemolytic streptococci? a. rheumatic fever, undulant fever b. glomerulonephritis, rheumatic fever c. rheumatic fever, tularemia d. glomerulonephritis, undulant fever b. glomerulonephritis, rheumatic fever b (Noninfectious sequelae associated with infection with Streptococcus pyogenes are glomerulonephritis and rheumatic fever.)
97) The enterotoxin produced by certain strains of hemolytic, coagulase positive Staphylococcus aureus: c. causes one type of bacterial food poisoning c (Staphylococcus aureus produces an enterotoxin that is associated with short- incubation food poisoning.)
98) A gamma-hemolytic Streptococcus that blackens bile esculin agar but does not grow in 6.5% NaCl broth is most likely: a. group B Streptococcus b. Enterococcus c. group D Streptococcus d. Streptococcus pneumoniae c. group D Streptococcus c (Group D streptococci and Enterococcus produce a positive bile esculin test; however, of these two, only Enterococcus grows in the presence of 6.5% NaCl.)
99) Gram stain examination from a blood culture bottle show dark blue, spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include: a. catalase production and coagulase test a (The Gram stain and culture growth describe a Staphylococcus species.
100) Gram-positive cocci in chains are seen on a Gram stain from a blood culture. The organism grows as a beta-hemolytic colony. Further tests that could be performed include: a. bile esculin, PYR, bacitracin, and hippurate a (Bile esculin, PYR, bacitracin and hippurate are biochemicals/tests used in the presumptive or definitive identification of beta-hemolytic streptococci such as S pyogenes, S agalactiae and Enterococcus.)
101) "Nutritionally deficient" streptococci are: a. enterococci b. group D nonenterococci c. cell wall-deficient streptococci d. in the genera Granulicatella and Abiotrophia d. in the genera Granulicatella and Abiotrophia
102) After 24 hrs. a blood culture from a newborn grows catalase-negative, gram-positive cocci. The bacterial colonies are small, translucent and beta-hemolytic on a blood agar plate. a. perform a Streptococcus group typing (The colony description and biochemical results presented describe Streptococcus agalactiae. The identification of this organism is confirmed by streptococcus antigen typing.)
03) A beta-hemolytic streptococcus that has been isolated from an ear culture grows up to the edge of a 0.04 unit bacitracin disk. Which of the following tests would help to determine if the organism is Enterococcus? a. growth in 6.5% NaCl broth a (Of the biochemicals listed, only growth in 6.5% NaCl will aid in the identification of Enterococcus, which has the ability to grow in the presence of high salt concentrations.)
104) The organism most commonly associated with neonatal purulent meningitis is: a. Neisseria meningitidis b. Streptococcus pneumoniae c. group B streptococci d. Haemophilus influenzae c. group B streptococci c (All of the organisms listed are potential causes of meningitis. Group B Streptococcus is associated with neonatal meningitis and meningitis in the elderly.)
105) An important cause of acute exudative pharyngitis is: a. Staphylococcus aureus (beta-hemolytic) b. Streptococcus pneumoniae c. Streptococcus agalactiae d. Streptococcus pyogenes d. Streptococcus pyogenes d (Streptococcus pyogenes is the cause of exudative pharyngitis, commonly called strep throat.)
106) Of the following bacteria, the most frequent cause of prosthetic heart valve infections occurring within 2-3 months after surgery is: a. Streptococcus pneumoniae b. Streptococcus pyogenes c. Staphylococcus aureus d. Staphylococcus epidermidis d. Staphylococcus epidermidis (Staphylococcus epidermidis is the most common cause of prosthetic valve endocarditis.)
108) A catheterized urine is inoculated onto blood and MacConkey agar using a 0.01 mL loop. After 48 hrs., 68 colonies of a small translucent nonhemolytic organism grew on blood agar but not MacConkey. Testing reveals small gram-positive, catalase-negativ c. growth of 6,800 colonies/mL of a Streptococcus species, esculin hydrolysis and NaCl growth test to follow c (The number of colonies isolated is multiplied by 100 when a 0.01 mL loop is used for inoculation. Gram-positive, catalase negative cocci are i
109) Children who have infections with beta-hemolytic streptococci can develop: a. acute pyelonephritis b. acute glomerulonephritis c. chronic glomerulonephritis d. nephrosis b. acute glomerulonephritis b (Noninfectious sequelae associated with infection with Streptococcus pyogenes are glomerulonephritis and rheumatic fever.)
110) A gram-positive coccus isolated from a blood culture has the following characteristics: optochin susceptibility: negative bacitracin susceptibility: negative bile esculin hydrolysis: negative hippurate hydrolysis: Positive catalase: negative d. Streptococcus agalactiae d (Streptococcus agalactiae is catalase and bile esculin hydrolysis negative and bacitracin and optochin resistant. Streptococcus agalactiae hydrolyzes hippurate.)
111) A beta-hemolytic streptococci that is bacitracin-sensitive and CAMP-negative is: a. group B b. group A c. beta-hemolytic, not group A, B or D d. beta-hemolytic, group D b. group A Streptococcus Pyogenes b (Group A streptococci [Streptococcus pyogenes] are susceptible to bacitracin and CAMP test negative.)
112) A beta-hemolytic Streptococcus that is bacitracin-resistant and CAMP-positive is: a. group A or B b. group A c. group B d. beta-hemolytic, group D c. group B Streptococcus Agalactiae c (Group B streptococci [Streptococcus agalactiae] are resistant to bacitracin and CAMP test positive.)
113) Group B, beta-hemolytic streptococci may be distinguished from other hemolytic streptococci by which of the following procedures? a. latex antigen typing b. growth in 6.5% NaCl broth c. growth on esculin medium d. bacitracin susceptibility a. latex antigen typing
114) It is important to differentiate between Enterococcus and group D streptococci because: d. enterococci often show more antibiotic resistance than group D streptococci d (Enterococcus species are more resistant to antimicrobial therapy than group D streptococci such as S bovis.)
115) Streptococcus pneumoniae can be differentiated best from the viridans group of streptococci by: a. Gram stain b. the type of hemolysis c. colonial morphology d. bile solubility d. bile solubility d (Bile solubility testing of alpha-hemolytic streptococci differentiates S pneumoniae [soluble] from other alpha-hemolytic streptococci such as viridans streptococci [insoluble].)
116) Characteristically, enterococci are: a. unable to grow in 6.5% NaCl b. relatively resistant to penicillin c. sodium hippurate positive d. bile esculin negative b. relatively resistant to penicillin
117) A beta-hemolytic, catalase-positive, gram-positive coccus is coagulase negative by the slide coagulase test. Which of the following is the most appropriate action in identification of this organism? d. do a tube coagulase test to confirm the slide test d (Staphylococcus aureus are usually beta-hemolytic. Some strains may not produce bound coagulase detected by the slide coagulase test. A tube coagulase is performed to detect free coagulase and sho
118) Which of the following would best differentiate Streptococcus agalactiae from Streptococcus pyogenes? a. ability to grow in sodium azide broth b. a positive bile-esculin reaction c. hydrolysis of sodium hippurate d. beta-hemolysis on sheep blood c. hydrolysis of sodium hippurate c (Of the biochemicals listed only hydrolysis of sodium hippurate will differentiate Streptococcus agalactiae [positive] from S pyogenes [negative].)
119) The most critical distinction between Staphylococcus aureus and other Staphylococcus is: a. phosphatase reaction b. DNA production c. coagulase production d. hemolysis c. coagulase production c (Coagulase production is the primary biochemical used to differentiate S aureus from other coagulase-negative staphylococci.)
120) Which of the following organisms is, to date, considered universally susceptible to penicillin: a. Haemophilus influenzae b. Neisseria gonorrhea c. Streptococcus pyogenes d. Corynebacterium diphtheriae c. Streptococcus pyogenes
121) A beta-hemolytic gram-positive coccus was isolated from the cerebrospinal fluid of a 2-day-old infant with signs of meningitis. The isolate grew on sheep blood agar under aerobic conditions and was resistant to a bacitracin disc. c. latex antigen typing c (The most likely organism isolated from this specimen is Streptococcus agalactiae. Polysaccharide antigen typing will confirm the identification of S agalactiae and differentiate it from other beta-hemolytic streptococci.)
122) How many hrs. after eating contaminated food do initial symptoms of staphylococcal food poisoning typically occur? a. 2 - 6 hrs. b. 12 - 18 hrs. c. 24 - 48 hrs. d. 72 hrs. a. 2 - 6 hrs. a (Staphylococcus aureus produces an enterotoxin that is associated with food poisoning. Symptoms typically appear within 2 - 6 hours.)
123) During the past month, Staphylococcus epidermidis has been isolated from blood cultures at 2 - 3 times the rate from the previous year. The most logical explanation for the increase in these isolates is that: c. there has been a break in proper skin preparation before drawing blood for culture Staphylococcus epidermidis is a common blood culture contaminant because it is a common inhabitant of the skin.)
125) A yellow colony from a wound culture tested catalase-positive and coagulase-negative. The organism gram-positive cocci in clusters. Which of the following tests should differentiate between a coagulase-negative Staphylococcus and Micrococcus? c. furazolidone (100 ug/disk) susceptibility c (Micrococcus and Staphylococcus can be differentiated by susceptibility to furazolidone [100 mg/disk]. Staphylococcus is susceptible and Micrococcus is resistant.)
127) An isolate of an unknown beta-hemolytic Streptococcus is streaked perpendicular to a streak of beta-lysin-producing Staphylococcus aureus. After incubation a zone of arrowhead hemolysis is noted at the interface of the 2 streaks. What is the name of d. CAMP test and S agalactiae d (The question describes the CAMP test, which is positive for Streptococcus agalactiae.)
128) Which of the following may be used as a positive quality control organism for the bile esculin test? a. Staphylococcus epidermidis b. Staphylococcus aureus c. Streptococcus pyogenes d. Enterococcus faecalis d. Enterococcus faecalis d (Enterococcus is positive for the bile esculin test while Streptococcus pyogenes and staphylococci are negative.)
129) Infection of the urinary tract is most frequently associated with: a. Staphylococcus aureus b. Escherichia coli c. Enterococcus faecalis d. Serratia marcescens b. Escherichia coli b (>80% of uncomplicated UTIs are caused by E coli.)
130) MacConkey media for screening suspected cases of hemorrhagic E coli O157:H7 must contain: a. indole b. citrate c. sorbitol d. lactose c. sorbitol c (Sorbitol replaces lactose in MacConkey. E coli 0157:H7 does not ferment sorbitol, whereas other species of E coli are positive for fermentation of sorbitol. This makes the media a good screen for 0157:H7.)
131) Members of the family Enterobacteriaceae share which one of the following characteristics? a. produce cytochrome oxidase b. ferment lactose c. produce beta-hemolysis d. reduce nitrate to nitrite d. reduce nitrate to nitrite d (Members of Enterobacteriaceae are oxidase negative, ferment glucose, and reduce nitrate to nitrite.)
132) Which one of the following genera is among the least biochemically reactive members of the Enterobacteriaceae? a. Proteus b. Pseudomonas c. Citrobacter d. Shigella d. Shigella d (Shigella is lactose negative, most species do not produce gas, are VP, urea, lysine decarboxylase and citrate negative, and they are nonmotile.)
133) Which one of the following gram-negative bacilli ferments glucose? a. Alcaligenes faecalis b. Pseudomonas cepacia c. Acinetobacter lwoffii d. Yersinia enterocolitica d. Yersinia enterocolitica d (Alcaligenes, Pseudomonas and Acinetobacter are all nonfermenters; Yersinia is a member of the Enterobacteriaceae and, by definition, ferments glucose.)
134) A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on SBA. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results: b. Klebsiella pneumoniae b (Klebsiella is the only distractor that is VP positive, and the other biochemical reactions are typical for K pneumoniae.)
135) An organism was inoculated to a TSI tube and gave the following reactions: alkaline slant/acid butt, H2S, gas produced This organism most likely is: a. Klebsiella pneumoniae b. Shigella dysenteriae c. Salmonella typhimurium d. Escherichia coli c. Salmonella typhimurium c (Salmonella is the only distractor that produces H2S. Also, Klebsiella and E coli produce acid/acid reactions in TSI.)
137) A TSI tube inoculated with an organism gave the following reactions: alkaline slant, acid butt, no H2S, no gas produced This organism is most likely: a. Yersinia enterocolitica b. Salmonella typhi d. Shigella dysenteriae d. Shigella dysenteriae d (Salmonella produce H2S in TSI and Yersinia produces an acid slant and acid butt. Shigella fits this biochemical profile.)
139) Which of the following organisms can grow in the small bowel and cause diarrhea in children, travelers' diarrhea, or a severe cholera-like syndrome through the production of enterotoxins? a. Yersinia enterocolitica b. Escherichia coli c. Salmonell b. Escherichia coli b (E coli can produce several different types of toxins that result in different gastroenteritis manifestations.)
141) Shigella species characteristically are: a. urease positive b. nonmotile c. oxidase positive d. lactose fermenters b. nonmotile b (The biochemical characteristic that best fits Shigella is that it is nonmotile. Shigella are urease negative and oxidase negative. Shigella are lactose nonfermenters.)
142) A gram-negative bacillus has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism does not agglutinate in Shigella antisera. What should be done next? d. boil the organism and retest with the antisera d (Some Shigella produce capsular antigen that mask the cell wall and boiling removes the capsule.)
143) Biochemical reactions of an organism are consistent with Shigella. A suspension is tested in antiserum without resulting agglutination. However, after 15 mins. of boiling, agglutination occurs in group D antisera. The Shigella species is d. sonnei d (Boiling removed the capsule so that the antiserum could react with cell wall antigen. Group D Shigella is S sonnei.)
150) presented to the ER with high fever, diarrhea and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A Wayson stain of the aspirate showed bacilli that were bipolar, resembling safety pins. d. Yersinia pestis d (Yersinia pestis is classically described as having a "safety pin" appearance on Wayson stain. This patient's presentation is classic for bubonic plague.)
152) A clean catch urine sample from a nursing home patient is cultured using a .001mL loop. It grows 67 colonies of a lactose fermenter that has the following biochemical reactions: c. 67,000 CFU/mL Enterobacter cloacae TSI: Acid/Acid,oxidase: negative,motility: positive,indole:negative,citrate: positive,VP: positive,lysine decarboxylase: negative,ornithine decarboxylase: positive,urea: negative
153) Plesiomonas shigelloides is a relatively new member of the family Enterobacteriaceae. What characteristic separates it from other members of the Enterbacteriaceae? a. it is oxidase positive b. it ferments glucose c. it produces pyocyanin d. it re a. it is oxidase positive a (Enterobacteriaceae ferment glucose and are oxidase negative. However, it was moved to the Enterobacteriaceae family despite its positive oxidase reaction.)
155) The stock cultures needed for quality control testing of motility are: a. Salmonella typhimurium / Escherichia coli b. Escherichia coli / Pseudomonas aeruginosa d. Klebsiella pneumoniae / Escherichia coli d. Klebsiella pneumoniae / Escherichia coli d (Of the organisms listed only Klebsiella pneumoniae is nonmotile.)
156) The stock cultures needed for quality control testing of oxidase production are: a. Escherichia coli / Klebsiella pneumoniae b. Salmonella typhimurium / Escherichia coli c. Escherichia coli / Pseudomonas aeruginosa d. Proteus mirabilis / Escheric c. Escherichia coli / Pseudomonas aeruginosa c (Of the organisms listed only Pseudomonas aeruginosa is oxidase positive.)
157) The stock cultures needed for quality control testing of phenylalanine deamination activity are: a. Escherichia coli / Klebsiella pneumoniae b. Salmonella typhimurium / Escherichia coli d. Proteus mirabilis / Escherichia coli d. Proteus mirabilis / Escherichia coli (Of the organisms listed only Proteus mirabilis is phenylalanine deaminase positive)
158) The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are: a. Salmonella typhimurium / Escherichia coli b. Escherichia coli / Pseudomonas aeruginosa d. Serratia marcescens / Escherichia coli d. Serratia marcescens / Escherichia coli (Of the organisms listed only Serratia marcescens is DNase positive.)
159) Quality control of the spot indole test requires the use of ATCC cultures of: a. Pseudomonas aeruginosa / Proteus mirabilis b. Salmonella typhi / Shigella sonne d. Escherichia coli / Enterobacter cloacae d. Escherichia coli / Enterobacter cloacae d (Quality control of indole requires both a positive and a negative control. E coli and E cloacae respectively produce a positive and negative reaction with indole.)
160) An organism that exhibits the satellite phenomenon around colonies of staphylococci is: a. Haemophilus influenzae b. Neisseria meningitidis c. Neisseria gonorrhoeae d. Klebsiella pneumoniae a. Haemophilus influenzae a (Haemophilus influenzae requires X and V factors. Sheep blood agar supplies X factor, and the staphylococci produce V factor, so colonies grow around staph colonies.)
161) An organism isolate from the surface of a skin burn is found to produce a diffusible green pigment on a blood agar plate. Further studies of the organism would most likely show the organism to be: a. Staphylococcus aureus d. Pseudomonas aeruginosa d. Pseudomonas aeruginosa (Pseudomonas aeruginosa produces the blue-green pigment, pyocyanin.)
162) A nonfermenting gram-negative bacillus is isolated from a wound. The nitrate and oxidase are strongly positive. The growth on SBA has a grape-like odor. The organism is: d. Pseudomonas aeruginosa (Pseudomonas aeruginosa often has a sweet odor that smells like grapes.)
163) A small, gram-negative bacillus is isolated from an eye culture. It grows only on chocolate agar and is oxidase-variable. The most likely organism is: a. Acinetobacter lwoffii b. Haemophilus influenzae c. Stenotrophomonas maltophilia b (Growth only on chocolate agar is typical for Haemophilus influenzae, which is a gram-negative coccobacillus that causes upper respiratory infections.)
165) The optimal incubator temp. for isolation of Campylobacter jejuni/coli group is: a. 4 C b. 20 C c. 25 C d. 42 C d. 42 C d (Campylobacter jejuni/coli grow better at 42 C than 37 C and other organisms in the colon are inhibited at this high temperature)
348) Respiratory syncytial virus is best isolated using a(n): a. nasopharyngeal aspirate b. cough plate c. expectorated sputum d. throat swab a. nasopharyngeal aspirate a (Respiratory syncytial virus [RSV] infected the ciliated respiratory epithelium of the upper respiratory tract. A nasopharyngeal swab or aspirate is the optimal specimen for RSV recovery.)
347) Which of the following indicates the presence of a viral infection in tissue smears or biopsies? a. cytopathic effect b. intranuclear inclusions c. cell lysis d. mononuclear inflammatory cells b. intranuclear inclusions b (In tissue smears or biopsy specimens, the presence of virally infected cells is indicated by intranuclear or intracytoplasmic inclusions.)
346) Virus transport medium containing penicillin, gentamicin and amphotericin is used to collect and transport specimens for virus culture because this medium: b. inhibits bacterial and fungal growth b (Antibiotics and antifungal agents are added to viral transport medium to inhibit the growth of bacteria and fungus.)
342) Which one of the following species of Mycobacterium does not usually fluoresce on fluorochrome stain? a. Mycobacterium fortuitum b. Mycobacterium tuberculosis c. Mycobacterium ulcerans d. Mycobacterium bovis . Mycobacterium fortuitum a (Rapidly growing mycobacteria such as Mycobacterium fortuitum may be <10% acid fast and may not stain with fluorochrome.)
341) Differentiation of Mycobacterium avium from Mycobacterium intracellulare can be accomplished by: a. nitrate reduction test b. Tween hydrolysis test c. resistance to 10 ug thiophene-2-carboxylic acid hydrazide (TCH) d. DNA probe . DNA probe (Mycobacterium avium and M intracellulare have the same biochemical pattern, but can be differentiated by the use of DNA probes.)
338) Photochromogens produce pigment when: a. kept in the dark at 22 C b. exposed to light for 1 hour c. grown in the presence of CO2 d. incubated with x-ray film b. exposed to light for 1 hour b (Pigment production is controlled by an oxygen-dependent, light-inducible enzyme in photochromogenic mycobacteria.)
335) The best medium for culture of Mycobacterium tuberculosis is: a. Bordet-Gengou agar b. Loeffler medium c. Lowenstein-Jensen medium d. cystine blood agar c. Lowenstein-Jensen medium c (Lowenstein-Jensen is an egg-based medium used to isolate AFB. The other media are not used for the isolation of AFB.)
334) In a suspected case of Hansen disease (leprosy), a presumptive diagnosis is established by: b. detection of weakly acid-fast bacilli in infected tissue b (Mycobacterium leprae cannot be cultured in vitro. A clinical diagnosis is made, supported by the presence of AFB in a biopsy specimen.)
333) Mycobacteria that produce pigment only after exposure to light are classified as: a. photochromogens b. scotochromogens c. rapid growers d. nonchromogens a. photochromogens a (Photochromogens produce nonpigmented colonies only when grown in darkness, but pigmented colonies after exposure to light.)
332) The mycobacteria that produce a deep yellow or orange pigment both in the dark and light are: a. photochromogens b. scotochromogens c. nonchromogens d. rapid growers b. scotochromogens b (Scotochromogens produce deep yellow or orange pigment when grown in either light or darkness.)
329) Which of the following is considered a primary drug for the treatment of Mycobacterium tuberculosis? a. rifampin b. kanamycin c. rifabutin d. ethionamide . rifampin a (Primary drugs for the treatment of Mycobacterium tuberculosis include isoniazid, rifampin, pyrazinamide, and ethambutol.)
327) AFB smear positive respiratory specimens may be reliably identified as Mycobacterium tuberculosis the same day the smear was read by: a. cording seen on the AFB smear b. nucleic acid amplification c. QuantiFERON-TB test d. DNA probes b. nucleic acid amplification (Several commercial PCR tests are available that identify Mycobacterium tuberculosis from positive respiratory specimens.)
326) Which species of Mycobacterium includes a BCG strain used for vaccination against tuberculosis? a. tuberculosis b. bovis c. kansasii d. fortuitum/chelonae complex b. bovis (Mycobacterium tuberculosis can remain viable but dormant in macrophages for many years.)
325) The disease-producing capacity of Mycobacterium tuberculosis depends primarily upon: a. production of exotoxin b. production of endotoxin c. capacity to withstand intracellular digestion by macrophages c. capacity to withstand intracellular digestion by macrophages c (Mycobacterium tuberculosis can remain viable but dormant in macrophages for many years.)
318) Tubercle bacilli are specifically stained by: a. crystal violet b. 1% acid fuchsin c. methylene blue d. carbol fuchsin d. carbol fuchsin
Created by: greeny9322
 

 



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