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23 Cards in this Set
- Front
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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 note: MTM, New York City, and Martin- Lewis agars contain blood factors needed to support the growth of N. gonorrhoeae as well as antibiotics that prevent growth of normal genital flora. Cultures must be incubated in 3% -7% CO2 at 35°C. Cultures should be held a minimum of 48 hours before being considered negative. |
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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 pneumonia |
a Neisseria gonorrhoeae note: Specimens for culture of N. gonorrhoeae are best if plated immediately or transported in a medium containing activated charcoal to absorb inhibitory substances that hinder their recovery. |
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The Superoxol test is used as a rapid presumptive test for: a Neisseria gonorrhoeae b Neisseria meningitidis c Neisseria lactamica d Moraxella (Branhamella) catarrhalis |
a Neisseria gonorrhoeae |
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Colonies are gray, translucent, smooth, glistening; may have dry, claylike consistency a Neisseria animaloris b Neisseria elongata c Moraxella lacunata d Moraxella catarrhalis |
b Neisseria elongata |
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Large, nonpigmented or gray, opaque, smooth; friable "hockey puck" consistency; colony may be moved intact over surface of agar: a Neisseria gonorrhoeae b Neisseria elongata c Moraxella osloensis d Moraxella catarrhalis |
d Moraxella catarrhalis |
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A penicillin-resistant Neisseria gonorrhoeae produces: a Alpha-hemolysin b Beta-lactamase c Enterotoxin d Coagulase |
b Beta-lactamase Antimicrobial resistance in Neisseria gonorrhea is widespread. The production of beta-lactamase (penicillinase breaks open the beta lactam ring of penicillin, destroying its activity. Thus, N. gonorrhoeae that produces beta lactamase are resistant to penicillin. |
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A gram-negative diplococcus that grows on modified Thayer-Martin medium can be further confirmed as Neisseria gonorrhoeae if it is: a Oxidase positive, glucose positive, and maltose positive b Oxidase positive and glucose positive, maltose negative c oxidase positive and maltose positive, glucose negative d Glucose positive, oxidase negative and maltose negative |
b Oxidase positive and glucose positive, maltose negative |
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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 Enterobacteriacee from gastrointestinal specimens d Streptococcus spp. from stool cultures |
c Enterobacteriacee from gastrointestinal specimens |
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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 Enterobacteriacee from gastrointestinal specimens d Streptococcus spp. from stool cultures |
c Enterobacteriacee from gastrointestinal specimens XLD agar is selective for gram-negative coliforms because of a high concentration (0.25%) of deoxycholate, which inhibits gram-positive bacteria. In addition, XLD is differential for Shigella and Salmonella spp. The medium contains xylose, lactose, and sucrose, which are fermented by most normal intestinal coliforms producing yellow colonies. Shigella does not ferment the sugars and produces red (or clear) colonies. Salmonella spp. ferment xylose; however, they also decarboxylate lysine in the medium, causing production of ammonia. Therefore, Salmonella first appear yellow but become red. Some Salmonella produce hydrogen sulfide (H2S) from sodium thiosulfate and therefore appear as red colonies with black centers. |
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SITUATION: A group of elementary students became ill after eating undercooked ground beef prepared in the school cafeteria. The suspected pathogen, E. coli serotype 0157:H7, is usually recovered using which of the following media? a XLD agar b MacConkey agar c MacConkey agar with sorbitol d Hektoen enteric agar |
b MacConkey agar E. coli 0157:H7 ferments lactose, and therefore, appears as dark pink colonies on MacConkey agar. To differentiate E. coli 0157:H7 from normal fecal flora, MacConkey agar with sorbitol is used. E. coli 0157:H7 does not ferment sorbitol, and usually are colorless colonies. |
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Biochemically, the Enterobacteriacee 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 |
a Ferment glucose, reduce nitrate to nitrite, and are oxidase negative |
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The Voges-Proskauer (VP) test detects which end product of glucose fermentation? a Acetoin b Nitrite c Acetic acid d Hydrogen sulfide |
a Acetoin Acetoin or acetylcarbinol, an end product of glucose fermentation, is converted to diacetyl after the addition of the VP reagents (a-naphthol and 40% potassium hydroxide (KOH]). Diacetyl is seen as a red- to pink-colored complex |
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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 Both MR and VP tests detect acid production from the fermentation of glucose. However, a positive MR test denotes a more complete catabolism of glucose to highly acidic end products such as formate and acetate than occurs with organisms that are VP positive only (e.g., Klebsiella pneumoniae). |
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A positive Simmons citrate test is seen as a: a Blue color in the medium after 24 hours of incubation at 35°C b Red color in the medium after 18 hours of incubation at 35°C c Yellow color in the medium after 24 hours of incubation at 35°C d Green color in the medium after 18 hours of incubation at 35°C |
a Blue color in the medium after 24 hours of incubation at 35°C The Simmons citrate test determines if an organism can utilize citrate as the sole source of carbon. The medium turns blue, indicating the presence of alkaline products such as carbonate. Tubes are incubated a minimum of 24 hours at 35°C with a loose cap before reading. |
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Which of the following reagents is added to detect the production of indole? a p-Dimethylaminobenzaldehyde b Bromcresol purple c Methyl red |
a p-Dimethylaminobenzaldehyde |
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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 Putrescine is the amine product of the decarboxylation of ornithine |
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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 PPM |
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Which genera of the Enterobacteriaceae are known to cause diarrhea and are considered enteric pathogens? a Enterobacter, Klebsiella, Providencia, and Proteus b Escherichia, Salmonella, Shigella, and Yersinia c Pseudomonas, Moraxella, Acinetobacter, and Aeromonas d Enterobacter, Citrobacter, and Morganella |
b Escherichia, Salmonella, Shigella, and Yersinia Escherichia, Salmonella, Shigella, and Yersinia are responsible for the majority of enteric diarrhea cases attributable to the Enterobacteriacee family. |
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Which genera of Enterobacteriaceae are usually nonmotile at 36°C? a Shigella, Klebsiella, and Yersinia b Escherichia, Edwardsiella, and Enterobacter c Proteus, Providencia, and Salmonella d Serratia, Morganella, and Hafnia |
a Shigella, Klebsiella, and Yersinia Shigella spp. and Klebsiella spp. are for the most part nonmotile. Yersinia can be motile at 22°C but is nonmotile at 36°C. |
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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. Shigella spp. and Campylobacter spp. are both causes of diarrhea, abdominal pain, fever, and sometimes vomiting. Blood is present in the stools of patients infected with Shigella as a result of invasion and penetration of the bowel. Young children may also exhibit bloody stools when infected with Campylobacter. |
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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 Campylobacter sp. c Screened for the detection of enterotoxigenic Escherichia coli d Placed in thioglycollate broth to detect Clostridium botulinum |
b Examined for the presence of Campylobacter sp. |
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Cold enrichment of feces (incubation at 4°C) in phosphate-buffered saline prior to subculture onto enteric media enhances the recovery of: a Enterotoxigenic E. coli b Salmonella paratyphi c Hafnia alvei d Yersinia enterocolitica |
d Yersinia enterocolitica Cold enrichment is especially useful when specimens contain large numbers of normal flora that are sensitive to prolonged exposure to near-freezing temperature. In addition to Yersinia, the technique has been used to enhance recovery of Listeria monocytogenes from specimens containing other bacteria. |
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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 More than 80% of uncomplicated UTIs are caused by Escherichia coli. |
