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30 Cards in this Set

  • Front
  • Back
Which of the following are alpha-hemolytic strep?
A. Streptococcus pneumoniae
B. viridans Streptococcus
C. Streptococcus agalactaiae
D. A & B
E. A, B, C
D. A & B.
Alpha hemolysis is defined as a partial hemolysis or green discoloration on sheep blood agar. The most important of the alpha-hemolytic Strep spp are the viridans Strep
and S. pneumoniae. S. agalactiae and S. pyogenes are true, or beta-hemolytic, organisms, while gamma, or non-hemolytic, Strep include the enterococci and S. bovis.
QCCP2, Specific bacteria key characteristics
Which of the following profiles best describes Streptococcus pneumoniae?
A. alpha-hemolytic, bile soluble, optochin sensitive
B. gamma hemolytic, bile esculin positive, PYR hydrolysis negative
C. gamma hemolytic, bile esculin positive, PYR hydrolysis positive
D. beta hemolytic, CAMP test positive, hippurate positive
E. beta hemolytic, bacitracin (A disk) sensitive, PYR hydrolysis positive
A. alpha-hemolytic, bile soluble, optochin-sensitive.
S. pneumoniae is among the green, or alpha-hemolytic, Strep, which also includes many of the viridans (which means “green”) Strep. Remember that S. pneumoniae is
optochin-sensitive, unlike viridans Strep.
QCCP2, Group D
Which best describes growth conditions for Neisseria?
A. microaerophilic at 37°C
B. microaerophilic at 30°C
C. CO2-rich at 30°C
D. CO2-rich at 35°C
E. anaerobic at 32°C
D. CO2-rich at 35°C.
Neisseria is not hardy and requires careful handling and growth conditions. It prefers chocolate agar (Thayer-Martin) with antibiotics. Cotton swabs inhibit the growth of
Neisseria, so Dacron swabs should be used to collect samples.
QCCP2, Gram-negative cocci
Which DNase positive organism's colony is not easily broken up and therefore displays the “hockey puck” sign where it can be pushed across the plate?
A. N. gonorrheae
B. M. catarrhalis
C. N. lactamica
D. V. cholerae
E. N. meningitidis
B. M. .
M. catarrhalis looks very similar to Neisseria spp (gram-negative kidney bean-shaped diplococci) and is also non-motile, oxidase positive and catalase positive. Unlike
Neisseria, it's DNase positive and displays the “hockey puck” sign (colonies stay intact and, when pushed, move along the media intact, like a hockey puck).
QCCP2, Gram-negative cocci
Which test can be used to differentiate Nocardia from Actinomyces?
A. acid fast stain
B. aerobic v. anaerobic growth conditions
C. gram stain
D. A & B
E. A, B, C
D. A & B.
Both are gram-positive, but Nocardia is weakly acid-fast and prefers aerobic conditions, while Actinomyces is not acid-fast and prefers anaerobic culture.
QCCP2, Gram-positive bacilli
Which of the following is an anaerobic spore-forming gram-positive bacillus?
A. Actinomyces
B. Clostridia
C. Lactobacillus
D. Bacillus
E. Listeria
B. C.
All are gram positive bacilli, but only Actinomyces, Clostridia, and Lactobacillus are anaerobes. Of those three, only Clostridia makes spores, too. Listeria and Bacillus are
aerobic, with Bacillus producing spores and Listeria not.
QCCP2, Gram-positive bacilli
Which of the following features of Bacillus anthracis can be used in distinguish it from Bacillus cereus?
A. lack of hemolysis
B. lack of motility
C. sensitivity to penicillin
D. A & B
E. A, B, C
Bacillus cereus is beta hemolytic and motile, unlike B. anthracis. Both are sensitive to penicillin and form spores. Also unlike B. cereus, B. anthracis forms medusa-headcolonies on sheep blood agar and produces a toxin containing edema factor, protective antigen, and lethal factor.
QCCP2, Aerobic gram-positive bacilli
Which organism is responsible for granulomatosis infantisepticum?
A. Erysipelothrix
B. Streptomyces
C. Rhodococcus
D. Corynebacterium
E. Listeria
E. L.
The tumbling motility, the cold enrichment and the preference for infecting pregnant women are all characteristics of Listeria. Because of the predilection for pregnant
women, there is the risk to infants born to infected mothers of granulomatosis infantisepticum, a condition described as multiple, disseminated suppurative abscesses
affecting numerous organs.
QCCP2, Listeria
Which enterobacteriaceae family member is non-motile at body temperature, but motile at room temperature?
A. Shigella
B. Yersinia
C. Kingella
D. Klebsiella
E. Serratia
B. Y.
Most enterobacteriaceae are motile with the exception of Shigella and Klebsiella. Yersinia is unique in only being motile at 22°C.
QCCP2, Gram-negative bacilli
Which of the following results of the Kligler iron agar/triple sugar iron (KIA/TSI) slant tests excludes enterobacteriaceae?
A. alkaline slant/alkaline butt
B. alkaline slant/acid butt
C. alkaline slant/acid butt with H2S production
D. acid slant/acid butt
E. acid slant/acid butt with H2S production
A. alkaline slant/alkaline butt.
The KIA/TSI test is a weird and wonderfully complex assay. Multiple characteristics are assayed simultaneously - aerobic (slant) v. anaerobic (butt) growth, fermentation of
sugar (pH change), and whether the organism produces H2S or gas. Glucose fermenters result in an alkaline slant and acid butt at 24 hours; lactose-fermenters have an
acid slant and acid butt. Given that enterobacteriaceae ferment glucose with or without lactose fermentation, an alkaline slant and alkaline butt excludes them.
QCCP2, Anaerobic gram-negative bacilli
Which biochemical test is used to distinguish between S. saprophyticus and S. epidermidis?
A. catalase
B. coagulase
C. NaCl tolerance
D. CAMP test
E. novobiocin
E. novobiocin.
Once the catalase test is positive, indicating Staphylococcus, and coagulase is negative (coagulase-negative Staph), the next test to do is the novobiocin test. The common
skin floral Staphylococcus epidermidis is susceptible to the antibiotic novobiocin, while S. saprophyticus is resistant. “Saprophyticus” means that it grows on dead material.
I remember that S. saprophyticus is “resistant” to “new (novo) life (bio).”
QCCP2, Novobiocin susceptibility
What is the purpose of the CAMP test?
A. to identify antibiotic-resistant Staphylococcus
B. to identify S. aureus
C. to identify Group B beta-hemolytic Strep
D. to identify Enterococci
C. to identify Group B beta-hemolytic S.
In the CAMP test, a single streak of Staphylococcus aureus is plated perpendicular to a streak of presumptive Group B beta-hemolytic Strep on a sheep blood agar plate. A
positive test is indicated by an “arrowhead” zone of beta hemolysis pointing toward the Staph streak. The reason is that the Group B Strep produce “CAMP Factor,” which
synergizes with the beta hemolysin of S. aureus. S. aureus is identified with the coagulase test; Enterococci can be identified with a number of tests including bile esculin
and 6.5% NaCl tolerance.
QCCP2, Biochemical tests
What is the purpose of the optochin (P)-test?
A. distinguish among alpha hemolytic Strep
B. distinguish among beta hemolytic Strep
C. to confirm PYR test
D. as a substitute for coagulase
E. to test for bile solubility
A. distinguish among alpha hemolytic S
The optochin, or P-disk test, is used to distinguish between alpha hemolytic Strep such as S. pneumoniae, which is optochin-sensitive, and the viridans Strep, which are
optochin-resistant. As a matter of fact, the optochin disk has a “P” on it for its relative specificity for pneumococcus.
QCCP2, Optochin
All the following organisms are oxidase positive, except:
A. Pseudomonas
B. Shigella
C. Vibrio
D. Campylobacter
E. Pasteurella
B. S .
Organisms of the Enterobacteriaceae family (E. coli, Shigella, Salmonella, Klebsiella, Proteus, etc.) are uniformly oxidase negative. It's actually part of the definition of the
family - oxidase negative glucose fermenters. The set of gram-negative oxidase-positive organisms include Pseudomonas, Campylobacter, Pasteurella, Vibrio, Aeromonas,Neisseria, and Brucella. One can hallucinate on PCP, a VAN driven by an OX named “Bruce.” Moraxella is also oxidase-positive, but it doesn't fit into my mnemonic. Sorry,
Moraxella.
QCCP2, Cytochrome oxidase
What organism best fits indole positive, lactose fermenter on MacConkey agar?
A. P. aeruginosa
B. E. coli
C. P. multocida
D. H. influenzae
E. Klebsiella
B. E. .
The indole test indicates the presence of bacterial tryptophanase, which metabolizes tryptophan into indole. While E. coli, Pasteurella, and H. influenzae are all positive for
indole, only E. coli is a lactose fermenter on MacConkey. Pseudomonas is indole (-) and a lactose non-fermenter, Klebsiella is a strong lactose fermenter, but is also indole
(-).
QCCP2, Indole
What test, when paired with the Voges-Proskauer, provides the exact opposite results?
A. CAMP test
B. Kirby-Bauer
C. cytochrome oxidase
D. nitrate reduction test
E. methyl red test
E. methyl red test.
Bacteria use one of two pathways to utilize pyruvate - one pathway results in mixed acid production, yielding a positive methyl red test, while if butylene glycol is produced,
they yield a positive Voges-Proskauer test. The two are mutually exclusive and therefore have opposite results.
QCCP2, Test
Which of the following organisms is a rapid urea splitter and therefore grows in both Stuart broth and Christensen broth?
A. Proteus
B. Klebsiella
C. Haemophilus
D. Neisseria
E. Branhamella
A. P.
Due to the high amount of buffer in Stuart broth, only strong urea-splitters, such as the Proteus spp, turn positive. There is less buffer in Christensen, and therefore it is
less selective, allowing weaker urea-splitting organisms, such as Klebsiella, to turn positive (red).
QCCP2, Laboratory methods
Which of the following organisms has peritrichous flagella?
A. Flavobacterium
B. Bordetella
C. Pseudomonas
D. Acinetobacter
E. Moraxella
B. B.
All of the choices are flagellated, but Bordetella is the only one of them with peritrichous, or circumferential, flagella. Acinetobacter, Moraxella, and Flavobacterium have
non-motile flagella, while Pseudomonas aeruginosa has a polar monotrichous flagellum.
QCCP2, Laboratory Methods
Which of the following organisms displays the “string sign”?
A. Vibrio vulnificus
B. Vibrio cholerae
C. Vibrio parahaemolyticus
D. A & B
E. A, B, C
B. V.
V. cholerae can be distinguished from other species of Vibrio with the string test. When added to 0.5% deoxycholate (bile salt), V. cholerae will string out from the mixture
and stay that way. Other species of Vibrio will cease to string out after a minute.
QCCP2, Laboratory Methods
Which of the following organisms utilizes both glucose and maltose when plated on cysteine-tryptic digest semi-solid agar?
A. Neisseria gonorrheae
B. Neisseria lactamica
C. Neisseria meningitidis
D. Moraxella catarrhalis
E. Haemophilus aphrophilus
C. N.
The carbohydrate tests for Neisseria are easily remembered - N. gonorrheae utilizes only glucose, N. meningitidis uses maltose and glucose, while N. lactamica utilizes
lactose, maltose, and glucose. Moraxella can't use any of those sugars as carbohydrate sources. Moraxella does however produce DNase, unlike the Neisseria spp.
QCCP2, Laboratory Methods
Which of the following organisms isolated from dog bite infections is coagulase positive?
A. Staphylococcus saprophyticus
B. Staphylococcus hyicus
C. Staphylococcus delphini
D. Staphylococcus intermedius
E. Staphylococcus epidermidis
D. S. .
S. saprophyticus and S. epidermidis are both coagulase-negative Staph species. S. hyicus, S. delphini, and S. intermedius are all coagulase-positive Staph species (along
with the more common S. aureus). S. intermedius is the most commonly isolated of the coagulase-positive Staph species isolated from infected dog bite sites.
QCCP2, Specific bacteria key characteristics
Which of the following tests is positive in Shigella?
A. lactose fermentation
B. Voges-Proskauer
C. methyl red
D. indole
E. motility
C. methyl red.
Testmanship and knowledge of some test characteristics would narrow down your choices to Voges-Proskauer and methyl red. Because the results of each test are always
opposites, one of them must be the positive, while the other is negative.
QCCP2, Shigella
Which of the following is responsible for most cases of red blood cell-transfusion-associated septic transfusion reactions?
A. Yersinia enterocolitica
B. Yersinia pestis
C. Yersinia pseudotuberculosis
D. Citrobacter
E. Edwardsiella
A. Y.
Because of its preference to grow in the cold, Yersinia contamination is a problem with blood products that are stored in the refrigerator, such as RBCs, and not so much
with platelets, which are stored at room temperature. Of the Yersinia spp, Y enterocolitica is most often isolated.
QCCP2, Yersinia
This organism can be distinguished from E. coli by its H2S production and from Salmonella by a positive indole test:
A. Citrobacter
B. Acinetobacter
C. Yersinia
D. Edwardsiella
E. Proteus
D. E.
Citrobacter also resembles Salmonella, but unlike Salmonella, it is positive in ONPG (beta-galactosidase) assay. Edwardsiella is also notable for coinfection with Entamoeba
and for its affinity to infect people with iron overload.
QCCP2, Edwardsiella
Infection with which strain of E. coli most closely resembles infection with V. cholerae?
A. ETEC
B. EIEC
C. EPEC
D. EHEC
E. EAggEC
A. ETEC.
Enterotoxigenic E. coli makes a toxin that functions similarly to Cholera toxin by stimulating the G proteins in the small intestine, leading to a profuse, watery secretory
diarrhea.
QCCP2, Escherichia
Which of the following results is most consistent and specific for E. coli O157:H7?
A. inability to ferment lactose
B. inability to ferment sorbitol
C. indole positivity
D. growth on MacConkey
E. positive string test
B. inability to ferment sorbitol.
E. coli O157:H7 is similar to other E. coli in that it can ferment lactose, grow on MacConkey agar, and is indole positive. Unlike other strains of E. coli, when O157:H7 is
plated on modified sorbitol: MacConkey agar substituted for lactose, the colonies grow clear instead of yellow.
QCCP2, EHEC
Which of the following organs act as a reservoir for Salmonella typhi, leading to intermittent bacteremia?
A. liver
B. gall bladder
C. spleen
D. A & B
E. A, B, C
E. A, B, C.
S. typhi is picked up by the reticuloendothelial system once it transverses the bowel wall. It can then remain hidden in macrophages in the liver, gall bladder, and spleen.
QCCP2, Salmonella
Which of the following V. cholerae O antigen types are associated with clinical cholera?
A. O1
B. O139
C. O232
D. A & B
E. A, B, C
D. A & B.
V. cholerae can be divided into strains that cause cholera (O1) and those that do not (non-O1). On the Indian subcontinent, subtype O139 is now recognized as a cause of
cholera.
QCCP2, V. cholerae
What is the optimal growth temperature for Pseudomonas?
A. 22°C
B. 30°C
C. 37°C
D. 42°C
E. 55°C
D. 42°C.
Pseudomonas grows at a temperature that would induce the expression of heat-shock proteins in most other bacteria.
QCCP2, Pseudomonas
Which of the following amino acids is required as a supplement in the growth media for Francisella tularensis?
A. phenylalanine
B. cysteine
C. tryptophan
D. proline
E. alanine
B. cysteine.
Francisella tularensis is a gram negative coccobacillus that doesn't grow on MacConkey and requires cysteine and cystine to grow.
QCCP2, Francisella