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***Medical Lab science review- Robert Harr 4th > Micro- Enterobacteriaceae > Flashcards

Micro- Enterobacteriaceae Flashcards

1
Q
  1. 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

A. Ferment glucose, reduce nitrate to nitrite, and
are oxidase negative

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2
Q
  1. 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.
A

B. Shigella spp. from some strains of Escherichia coli

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3
Q
  1. The Voges–Proskauer (VP) test detects which
    end product of glucose fermentation?
    A. Acetoin
    B. Nitrite
    C. Acetic acid
    D. Hydrogen sulfide
A

A. Acetoin

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4
Q
  1. At which pH does the methyl red (MR) test
    become positive?
    A. 7.0
    B. 6.5
    C. 6.0
    D. 4.5
A

D. 4.5

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5
Q
  1. 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

A. Blue color in the medium after 24 hours of
incubation at 35°C

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6
Q
  1. In the test for urease production, ammonia reacts
    to form which product?
    A. Ammonium citrate
    B. Ammonium carbonate
    C. Ammonium oxalate
    D. Ammonium nitrate
A

B. Ammonium carbonate

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7
Q
  1. 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

A. p-Dimethylaminobenzaldehyde

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8
Q
  1. Decarboxylation of the amino acids lysine,
    ornithine, and arginine results in the
    formation of:
    A. Ammonia
    B. Urea
    C. CO2
    D. Amines
A

D. Amines

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9
Q
  1. Lysine iron agar (LIA) showing a purple slant
    and a blackened butt indicates:
    A. E. coli
    B. Citrobacter spp.
    C. Salmonella spp.
    D. Proteus spp.
A

C. Salmonella spp.

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10
Q
  1. Putrescine is an alkaline amine product of which
    bacterial enzyme?
    A. Arginine decarboxylase
    B. Phenylalanine deaminase
    C. Ornithine decarboxylase
    D. Lysine decarboxylase
A

C. Ornithine decarboxylase

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11
Q
  1. 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
A

B. Morganella, Providencia, and Proteus

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12
Q
  1. Kligler iron agar (KIA) differs from triple-sugar
    iron agar (TSI) in the:
    A. Ratio of lactose to glucose
    B. Ability to detect H2S production
    C. Use of sucrose in the medium
    D. Color reaction denoting production of acid
A

C. Use of sucrose in the medium

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13
Q
  1. The malonate test is most useful in differentiating
    which members of the Enterobacteriaceae?
    A. Shigella
    B. Proteus
    C. Salmonella subgroups 2, 3 (the former Arizona)
    D. Serratia
A

C. Salmonella subgroups 2, 3 (the former Arizona)

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14
Q
  1. 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
A

B. Escherichia, Salmonella, Shigella, and Yersinia

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15
Q
  1. An isolate of E. coli recovered from the stool of a
    patient with severe bloody diarrhea should be
    tested for which sugar before sending it to a
    reference laboratory for serotyping?
    A. Sorbitol (fermentation)
    B. Mannitol (oxidation)
    C. Raffinose (fermentation)
    D. Sucrose (fermentation
A

A. Sorbitol (fermentation)

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16
Q
  1. 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

A. E. coli

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17
Q
  1. Which species of Shigella is most commonly
    associated with diarrheal disease in the
    United States?
    A. S. dysenteriae
    B. S. flexneri
    C. S. boydii
    D. S. sonnei
A

D. S. sonnei

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18
Q
  1. 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
A

B. Lactose, indole, ONPG, and motility

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19
Q
  1. 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

A. Shigella, Klebsiella, and Yersinia

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20
Q
  1. 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

A. Campylobacter spp.

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21
Q
  1. 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. Y. enterocolitica
A

D. Y. enterocolitica

22
Q
  1. Which group of tests, along with colonial
    morphology on primary media, aids most in the
    rapid identification of the Enterobacteriaceae?
    A. MR and VP, urease, and blood agar plate
    B. Phenylalanine deaminase, urease, and CDC
    agar plate
    C. Bacitracin, β-lactamase, and MacConkey agar
    plate
    D. Indole, oxidase, MacConkey, and blood agar
    plates
A

D. Indole, oxidase, MacConkey, and blood agar
plates

23
Q
  1. A routine, complete stool culture procedure should
    include media for the isolation of E. coli O157:H7
    as well as:
    A. Salmonella, Shigella, Yersinia, Campylobacter,
    and Staphylococcus aureus
    B. Vibrio cholerae, Brucella, and Yersinia spp.
    C. S. aureus, group B streptococci, and group D
    streptococci
    D. Clostridium difficile, Clostridium perfringens, and
    Yersinia spp.
A

A. Salmonella, Shigella, Yersinia, Campylobacter,
and Staphylococcus aureus

24
Q
  1. Which group of tests best identifies the Morganella
    and Proteus genera?
    A. Motility, urease, and phenylalanine deaminase
    B. Malonate, glucose fermentation, and
    deoxyribonuclease (DNase)
    C. Indole, oxidase, MR, and VP
    D. Indole, citrate, and urease
A

A. Motility, urease, and phenylalanine deaminase

25
Q
  1. Which group of tests best differentiates Enterobacter
    aerogenes from Edwardsiella tarda?
    A. Motility, citrate, and urease
    B. Hydrogen sulfide (H2S) production, sucrose
    fermentation, indole, and VP
    C. Lysine decarboxylase, urease, and arginine
    dihydrolase
    D. Motility, H2S production, and DNase
A

B. Hydrogen sulfide (H2S) production, sucrose
fermentation, indole, and VP

26
Q
  1. Enterobacter sakazakii can best be differentiated
    from Enterobacter cloacae by which of the
    following characteristics?
    A. Yellow pigmentation and negative sorbitol
    fermentation
    B. Pink pigmentation and positive arginine
    dihydrolase
    C. Yellow pigmentation and positive urease
    D. H2S production on TSI
A

A. Yellow pigmentation and negative sorbitol
fermentation

27
Q
  1. Members of the genus Cedecea are best
    differentiated from Serratia spp. by which
    test result?
    A. Positive motility
    B. Positive urease
    C. Positive phenylalanine deaminase
    D. Negative DNase
A

D. Negative DNase

28
Q
  1. Which of the following organisms is often
    confused with the Salmonella species
    biochemically and on plated media?
    A. E. coli
    B. Citrobacter freundii
    C. Enterobacter cloacae
    D. Shigella dysenteriae
A

B. Citrobacter freundii

29
Q
  1. 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.
A

B. Morganella spp.

30
Q
  1. Which single test best separates Klebsiella oxytoca
    from K. pneumoniae?
    A. Urease
    B. Sucrose
    C. Citrate
    D. Indole
A

D. Indole

31
Q
  1. Which of the following organisms, found in
    normal fecal flora, may be mistaken biochemically
    for the genus Yersinia?
    A. Klebsiella spp.
    B. Proteus spp.
    C. E. coli
    D. Enterobacter spp.
A

B. Proteus spp.

32
Q
  1. Why might it be necessary for both pink
    (lactose-positive) and colorless (lactose-negative)
    colonies from an initial stool culture on
    MacConkey agar to be subcultured and tested
    further for possible pathogens?
    A. Most Shigella strains are lactose positive
    B. Most Salmonella strains are maltose negative
    C. Most Proteus spp. are lactose negative
    D. Pathogenic E. coli can be lactose positive or
    lactose negative
A

D. Pathogenic E. coli can be lactose positive or
lactose negative

33
Q
  1. Which agar that is used for routine stool cultures
    is the medium of choice for the isolation of
    Yersinia strains from stool specimens?
    A. Salmonella–Shigella agar
    B. Hektoen enteric agar
    C. MacConkey agar
    D. CNA agar
A

C. MacConkey agar

34
Q
  1. Which organism is sometimes mistaken for
    Salmonella and will agglutinate in Salmonella
    polyvalent antiserum?
    A. C. freundii strains
    B. Proteus mirabilis strains
    C. S. sonnei strains
    D. E. coli
A

A. C. freundii strains

35
Q
  1. A bloody stool cultured from a 26-year-old
    woman after 3 days of severe diarrhea showed
    the following results at 48 hours after being
    plated on the following media:
    MacConkey agar: little normal flora with many
    non–lactose-fermenting colonies
    Hektoen enteric agar: many blue-green colonies
    Campylobacter blood agar and C. difficile agar:
    no growth
    Clear colonies (from MacConkey agar) tested
    negative for oxidase, indole, urease, motility,
    and H2S
    The most likely identification is:
    A. Shigella spp.
    B. Salmonella spp.
    C. Proteus spp.
    D. E. coli
A

A. Shigella spp.

36
Q
  1. Which of the following organisms are generally
    positive for β-galactosidase?
    A. Salmonella spp.
    B. Shigella spp.
    C. Proteus spp.
    D. E. coli
A

D. E. coli

37
Q
  1. In the Kauffmann–White schema, the combined
    antigens used for serological identification of the
    Salmonella spp. are:
    A. O antigens
    B. H antigens
    C. Vi and H antigens
    D. O, Vi, and H antigens
A

D. O, Vi, and H antigens

38
Q
  1. 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

A. Aminoglycosides, trimethoprim–sulfamethoxazole,
third-generation cephalosporins

39
Q
  1. The Shiga-like toxin (verotoxin) is produced
    mainly by which Enterobacteriaceae?
    A. Klebsiella pneumoniae
    B. E. coli
    C. Salmonella typhimurium
    D. Enterobacter cloacae
A

B. E. coli

40
Q
  1. Infections caused by Yersinia pestis are rare in the
    United States. Those cases that do occur are most
    frequently located in which region?
    A. New Mexico, Arizona, and California
    B. Alaska, Oregon, and Utah
    C. North and South Carolina and Virginia
    D. Ohio, Michigan, and Indiana
A

A. New Mexico, Arizona, and California

41
Q
  1. A leg culture from a nursing home patient grew
    gram-negative rods on MacConkey agar as pink to
    dark pink oxidase-negative colonies. Given the
    following results, which is the most likely
    organism?
    TSI = A/A
    Indole = Neg
    MR = Neg
    VP = +
    Citrate = +
    H2S = Neg
    Urease = +
    Motility = Neg
    Antibiotic susceptibility: resistant to carbenicillin
    and ampicillin

A. Serratia marcescens
B. Proteus vulgaris
C. Enterobacter cloacae
D. Klebsiella pneumoniae

A

D. Klebsiella pneumoniae

42
Q
  1. Four blood cultures were taken over a 24-hour
    period from a 20-year-old woman with severe
    diarrhea. The cultures grew motile (room
    temperature), gram-negative rods. A urine
    specimen obtained by catheterization also showed
    gram-negative rods, 100,000 col/mL. Given the
    following results, which is the most likely
    organism?
    TSI = A/A gas
    Indole = +
    VP = Neg
    MR = +
    H2S = Neg
    Citrate = Neg
    Urease = Neg
    Lysine decarboxylase = +
    Phenylalanine deaminase = Neg

A. Proteus vulgaris
B. Salmonella typhi
C. Yersinia enterocolitica
D. E. coli

A

D. E. coli

43
Q
  1. A stool culture from a 30-year-old man suffering
    from bloody mucoid diarrhea gave the following
    results on differential enteric media:
    MacConkey agar = clear colonies;
    XLD agar = clear colonies;
    Hektoen agar = green colonies;
    Salmonella–Shigella agar = small, clear colonies

Which tests are most appropriate for identification
of this enteric pathogen?
A. TSI, motility, indole, urease, Shigella typing with
polyvalent sera
B. TSI, motility, indole, lysine, Salmonella typing
with polyvalent sera
C. TSI, indole, MR, VP, citrate
D. TSI, indole, MR, and urease

A

A. TSI, motility, indole, urease, Shigella typing with
polyvalent sera

44
Q
  1. A leg-wound culture from a hospitalized
    70-year-old diabetic man grew motile,
    lactose-negative colonies on MacConkey agar.
    Given the following biochemical reactions at
    24 hours, what is the most probable organism?
    H2S (TSI) = Neg
    Indole = Neg
    MR = Neg
    VP = +
    DNase = +
    Citrate = +
    Urease = Neg
    Phenylalanine deaminase = Neg
    Ornithine and lysine decarboxylase = +
    Arginine decarboxylase = Neg
    Gelatin hydrolysis = +

A. Proteus vulgaris
B. Serratia marcescens
C. Proteus mirabilis
D. Enterobacter cloacae

A

B. Serratia marcescens

45
Q
  1. Three blood cultures taken from a 30-year-old
    cancer patient receiving chemotherapy and
    admitted with a urinary tract infection grew
    lactose-negative, motile, gram-negative rods
    prior to antibiotic therapy. Given the following
    biochemical reactions, which is the most likely
    organism?
    H2S (TSI) = +
    Indole = +
    MR = +
    VP = Neg
    Citrate = Neg
    Urease = +
    DNase = + Phenylalanine deaminase = +
    Gelatin hydrolysis = +
    Ornithine decarboxylase = Neg

A. Proteus vulgaris
B. Proteus mirabilis
C. Serratia marcescens
D. Klebsiella pneumoniae

A

A. Proteus vulgaris

46
Q
  1. Three consecutive stool cultures from a 25-year-old
    male patient produced scant normal fecal flora on
    MacConkey and Hektoen agars. However, colonies
    on CIN agar (cefsulodin–irgasan–novobiocin)
    displayed “bulls-eye” colonies after 48 hours
    incubation. The patient had been suffering from
    enterocolitis with fever, diarrhea, and abdominal
    pain for 2 days. What is the most likely
    identification of this gram-negative rod?
    A. E. coli
    B. Proteus mirabilis
    C. Yersinia enterocolitica
    D. Klebsiella pneumoniae
A

C. Yersinia enterocolitica

47
Q
  1. A 6-year-old female patient was admitted to
    the hospital following 2 days of severe diarrhea.
    Cultures from three consecutive stool samples
    contained blood and mucus. Patient history
    revealed a hamburger lunch at a fast-food
    restaurant 3 days earlier. Which pathogen is
    most likely responsible for the following results?
    Growth on:
    XLD agar = yellow colonies
    HE agar = yellow colonies
    Mac agar = light pink and dark pink colonies
    Mac with sorbitol agar – few dark pink and many
    colorless colonies
    A. Salmonella spp.
    B. Shigella spp.
    C. E. coli O157:H7
    D. Yersinia enterocolitica
A

C. E. coli O157:H7

48
Q
  1. 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

A. Yersinia pestis

49
Q
  1. 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
A

B. E. coli O157:H7, Salmonella spp., Shigella spp.

50
Q
  1. Direct spread of pneumonic plague disease occurs
    by which route?
    A. Fecal–oral route
    B. Rat bite
    C. Ingestion of contaminated tissue
    D. Inhalation of contaminated airborne droplets
A

D. Inhalation of contaminated airborne droplets

51
Q
  1. Which isolates of the Enterobacteriaceae family
    most commonly produce extended-spectrum
    β-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

A. E. coli and Klebsiella pneumoniae

***Medical Lab science review- Robert Harr 4th (63 decks)

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