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BACTERIOLOGY QUIZ

Terms in this set (49)

The red arrow in the photograph is pointing to a typical arrowhead-shaped zone of hemolysis that is produced in the CAMP test. A beta-hemolytic Gram-positive bacillus that produces a rectangular-shaped area of hemolysis as shown by the blue arrow is: *
Listeria monocytogenes
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This is a catalase-positive, coagulase-negative, gram-positive coccus isolated from a urine specimen from a 20-year-old female college student. The image shown is a Mueller Hinton plate streaked with a 0.5 MacFarland standardized inoculum and a 5 microgram disk of novobiocin after overnight incubation. What is the identification of the isolate? *
Staphylococcus saprophyticus
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Staphylococcus aureus has a distinctive appearance on which one of the following media?
Sheep Blood Agar
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MRVP broth is inoculated and incubated for 48 hours. What 2 reagents must be added to determine if the bacterium is VP positive? *
Alpha-naphthol and 40% KOH
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If a Quellung test was done on the following bacterial isolates, which one would you expect to be positive? *
Streptococcus pneumoniae
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A joint fluid was received in the microbiology laboratory. The specimen was cloudy and many neutrophils with intracellular and extracellular Gram negative diplococci were seen on the Gram stain. The specimen was inoculated to sheep blood and chocolate agar and grew a small, grayish white colony on chocolate with no growth observed on the sheep blood. Which of the following is most likely the organism? *
Neisseria gonorrhoeae
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A sputum sample was brought to the laboratory for analysis. Gram stain revealed the following: 10-15 epithelial cells per low-power field, 8-10 WBCs/ LPF, and pleomorphic Gram-negative rods. Which of the following interpretations should you make? *
Ask the patient to recollect sputum sample
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Kingella kingae is usually associated with which type of infection? *
Endocarditis
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Haemophilus ducreyi requires Factor X but not Factor V. Haemophilus parainfluenzae requires Factor V but not Factor X. *
Both statements are correct
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A positive Simmon's Citrate test is seen as a: *
Blue color
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Which of the following is true regarding Escherichia coli serotype O157:H7? *
Sorbitol nonfermenter
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The attached photograph shows a Christiansen's Urea slant four hours after it was inoculated with a Gram-negative rod. Which of the following organisms is the most likely? *
Proteus mirabilis
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All of the following are capnophilic bacteria which requires 5-10% CO2, EXCEPT: I. Campylobacter jejuni II. Haemophilus influenzae III. Neisseria gonorrheae IV. Helicobacter pylori *
I, IV
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The appropriate culture media for the recovery of Gardnerella vaginalis is: *
HBT Agar
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Which of the following tests can differentiate Bacillus anthracis from Bacillus cereus? I. Motility II. Hemolysis on SBA III. Lecithinase production IV. Gelatin Hydrolysis *
I, II, IV
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Optimal recovery of Francisella tularensis is acquired by:
Enriched media containing cysteine
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Chemical reagent used as mordant in Kinyoun method for acid-fast staing
tergitol
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Which o the following tests detects the production of mixed acids as a result of glucose fermentation
Methyl Red Test
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An oxidase-negative, gram-negative bacillus that produces an alkaline slant and acid butt on triple sugar iron (TSI) agar is able to ferment which of the following carbohydrates? *
Glucose only
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A beta-hemolytic, catalase-negative, gram-positive coccus is found to be hippurate hydrolysis positive and resistant to bacitracin. Which of the following is a likely presumptive identification? *
Group B Streptococci
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Which of the following nonphotochromogen slow grower Mycobacteria species will be ruled out if niacin is negative? *
Mycobacterium tuberculosis
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Tests to differentiate Streptococcus pneumoniae and Viridans Streptococci: I. Taxo A II. Bacitracin III. Taxo P IV. Optochin *
I, II, III, IV
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What is the appearance of Salmonella on Salmonella-Shigella Agar
Colorless with black centers
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The colonies growing on the blood agar plate, as shown in the upper image, are gray, white, and swarming. Note in the image below, that the colonies growing on XLD agar have black centers with pigmentation that does not extend into the agar. A presumptive identification of Proteus species can be made. Select the biochemical reaction that serves to separate Proteus vulgaris from Proteus mirabilis. *
Positive indole
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Colonies are small- to medium-sized, opaque, shiny, nonhemolytic, pale beige or yellowish color, has a gliding motility may be observed as outgrowths from the colonies or as a haze on the surface of the agar. What bacteria is being described? *
Capnocytophaga
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An organism that can live and grow in reduced concentrations of oxygen but prefers an anaerobic environment is known as a/an: *
Aerotolerant anaerobe
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A gram-positive bacillus was isolated from a wound specimen and had the following characteristics: double zone of beta-hemolysis, lecithinase positive, lipase negative, indole negative. What is the most likely identification of this organism? *
Clostridium perfringens
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A gram-negative, oxidase-negative coccobacillus was isolated from a patient's CSF. The organism produced dark pink colonies on MacConkey agar and had the following biochemical results: TSIA: A/Ag H2S (-), indole positive, motile, urease negative and citrate negative. The most probable identity of this organism is: *
Escherichia coli
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The following is the primary virulence factor produced by Streptococcus pneumoniae that prevents phagocytosis:
Capsule
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A gram-negative diplococcus is isolated from a throat culture. The isolate grows on Thayer-Martin agar, produces acid from maltose, lactose, and glucose and is ONPG positive. What is the most likely identification of this isolate? *
Neisseria lactamica
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The colonies illustrated in the top photograph are 48-hour-old colonies growing on the surface of blood agar that had been incubated anaerobically. The colonies are small, gray-white, and convex with irregular borders and internal flecking. Long, slender fusiform Gram-negative bacilli with tapered ends are seen in the Gram stain as observed in the bottom photomicrograph. The indole reaction is strongly positive and glucose fermentation is variable; other biochemical reactions are negative except for H2S production by some strains. This isolate is commensal in the upper respiratory tract and has been associated with hospital-acquired aspiration pneumonia, lung abscesses, and empyema in hospitalized patients. Based on these observations, select from the multiple choices the name of this isolate. *
Fusobacterium nucleatum
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The only oxidase positive member of Enterobacteriaceae: *
Plesiomonas
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What step in the Gram stain distinguishes between gram-positive and gram-negative organisms?
Decolorization using acetone alcohol
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Which type of enrichment media is used to isolate Group B Streptococcus? *
Todd Hewitt Broth
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The complete clearing of media around bacterial colonies on a blood agar plate is referred to as: *
Beta Hemolysis
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When an erythromycin resistant and clindamycin susceptible Staphylococcal isolate is encountered, a D-zone test for inducible clindamycin resistance must be performed before clindamycin is reported to be susceptible. Following overnight incubation, flattening of the clindamycin zone between the two disks occurred. This is reported as: *
Erythromycin resistant, clindamycin resistant
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Enterobacteriaceae are typically gram-negative and: *
Capable of reducing nitrates to nitrites
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Which Escherichia coli produces a heat-labile enterotoxin and a heat-stable enterotoxin? *
ETEC
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Bile salts and crystal violet are incorporated into MacConkey agar in order to: *
Inhibit the growth of gram-positive organisms
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The characteristic colony morphology of Actinomyces israelii on solid agar resembles: *
Molar tooth
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A suspected isolate of Vibrio spp. is isolated from a young child with diarrhea. The organism is identified as a curved, gram-negative rod, oxidase, lactose, and sucrose positive, that produces yellow colonies on TCBS. This organism is most likely: *
Vibrio cholerae
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All of the following have been used to describe colonies of Streptobacillus monoliformis except: *
Mercury drops
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An organism grows on blood agar at room temperature and nutrient agar at 35°C. The organism does not oxidize lactose, maltose, and glucose, is nitrate positive, and DNase positive. This organism is: *
Moraxella catarrhalis
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It causes rat-bite fever with sodoku. *
Spirillum minus
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Illustrated in the left tube of this photograph is a positive Voges Proskauer reaction (left tube). The red pigment is produced from the reactions of: *
Alpha naphthol with diacetyl
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The ethanol shock procedure is used to differentiate: *
Clostridium and Bacteroides spp.
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Psittacosis is a lower respiratory infection in humans caused by contact with what animal? *
Birds
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Its characteristic odor resembles chocolate cake. *
Proteus vulgaris
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The distinctly large, spreading, mucoid colonies seen on blood agar in the upper left image, and the display of lactose fermentation on MacConkey agar in the upper right image provide for a presumptive organism identification. This species is most commonly recovered from respiratory specimens of patients with pneumonia. Observing absence of motility, a weak reaction for urea, and strong reactions for citrate and Voges-Proskauer confirm the presumptive identification. From the multiple choices, select the name of the isolate presented here. *
Klebsiella pneumoniae
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