Micro-Nonfermentative Bacilli

Question 1

1. What are the most appropriate screening tests
   to presumptively differentiate and identify the
   nonfermentative gram-negative bacilli (NFB)
   from the Enterobacteriaceae?
   A. Catalase, decarboxylation of arginine, growth on
   blood agar
   B. Motility, urease, morphology on blood agar
   C. Oxidase, TSI, nitrate reduction, growth on
   MacConkey agar
   D. Oxidase, indole, and growth on blood agar

Answer 1

C. Oxidase, TSI, nitrate reduction, growth on
MacConkey agar

Question 2

2. Presumptive tests used for identification of the
   Pseudomonas spp. are:
   A. Oxidase, oxidation–fermentation (OF) glucose
   (open), OF glucose (sealed), motility, pigment
   production
   B. Growth on blood agar plate (BAP) and
   eosin–methylene blue (EMB) agars, lysine
   decarboxylation, catalase
   C. Growth on MacConkey, EMB, and XLD agars
   and motility
   D. Growth on mannitol salt agar and flagellar stain

Answer 2

A. Oxidase, oxidation–fermentation (OF) glucose
(open), OF glucose (sealed), motility, pigment
production

Question 3

3. Which tests are most appropriate to differentiate
   between Pseudomonas aeruginosa and
   Pseudomonas putida?
   A. Oxidase, motility, pyoverdin
   B. Oxidase, motility, lactose
   C. Oxidase, ONPG, DNase
   D. Mannitol, nitrate reduction, growth at 42°C

Answer 3

D. Mannitol, nitrate reduction, growth at 42°C

Question 4

4. Which test group best differentiates Acinetobacter
   baumannii from P. aeruginosa?
   A. Oxidase, motility, NO3 reduction
   B. MacConkey growth, 37°C growth, catalase
   C. Blood agar growth, oxidase, catalase
   D. Oxidase, TSI, MacConkey growth

Answer 4

A. Oxidase, motility, NO3 reduction

Question 5

5. In addition to motility, which test best differentiates
   Acinetobacter spp. and Alcaligenes spp.?
   A. TSI
   B. Oxidase
   C. Catalase
   D. Flagellar stain

Answer 5

B. Oxidase

Question 6

6. The most noted differences between P. aeruginosa
   and Stenotrophomonas maltophilia are:
   A. Oxidase, catalase, and TSI
   B. Oxidase, catalase, and ONPG
   C. Oxidase, 42°C growth, and polar tuft of flagella
   D. Catalase, TSI, and pigment

Answer 6

C. Oxidase, 42°C growth, and polar tuft of flagella

Question 7

7. Which Pseudomonas is usually associated with a
   lung infection related to cystic fibrosis?
   A. P. fluorescens
   B. P. aeruginosa
   C. P. putida
   D. Burkholderia pseudomallei

Answer 7

B. P. aeruginosa

Question 8

8. A nonfermenter recovered from an eye wound is
   oxidase positive, motile with polar monotrichous
   flagella, and grows at 42°C. Colonies are dry,
   wrinkled or smooth, buff to light brown in color,
   and are difficult to remove from the agar. In which
   DNA homology group should this organism be
   placed?
   A. Pseudomonas stutzeri
   B. Pseudomonas fluorescens
   C. Pseudomonas alcaligenes
   D. Pseudomonas diminuta

Answer 8

A. Pseudomonas stutzeri

Question 9

9. Which organism is associated with
   immunodeficiency syndromes and melioidosis
   (a glanders-like disease in Southeast Asia and
   northern Australia)?
   A. Pseudomonas aeruginosa
   B. Pseudomonas stutzeri
   C. Pseudomonas putida
   D. Burkholderia pseudomallei

Answer 9

D. Burkholderia pseudomallei

Question 10

10. Which biochemical tests are needed to differentiate
    Burkholderia cepacia from S. maltophilia?
    A. Pigment on blood agar, oxidase, DNase
    B. Pigment on MacConkey agar, flagellar stain,
    motility
    C. Glucose, maltose, lysine decarboxylase
    D. TSI, motility, oxidase

Answer 10

A. Pigment on blood agar, oxidase, DNase

Question 11

11. The following results were obtained from a pure
    culture of gram-negative rods recovered from the
    pulmonary secretions of a 10-year-old cystic
    fibrosis patient with pneumonia:

Oxidase = +
Motility = +
Glucose OF (open) = + Gelatin hydrolysis = +
Pigment = Red Arginine dihydrolase = +
(nonfluorescent)
Growth at 42°C = +
Flagella = + (polar, monotrichous)

Which is the most likely organism?
A. Burkholderia pseudomallei
B. Pseudomonas stutzeri
C. Burkholderia cepacia
D. Pseudomonas aeruginosa

Answer 11

D. Pseudomonas aeruginosa

Question 12

12. Alcaligenes faecalis (formerly A. odorans) is
    distinguished from Bordetella bronchiseptica
    with which test?
    A. Urease (rapid)
    B. Oxidase
    C. Growth on MacConkey agar
    D. Motility

Answer 12

A. Urease (rapid)

Question 13

13. Chryseobacterium spp. are easily distinguished
    from Acinetobacter spp. by which of the following
    two tests?
    A. Oxidase, growth on MacConkey agar
    B. Oxidase and OF (glucose)
    C. TSI and urea hydrolysis
    D. TSI and VP

Answer 13

A. Oxidase, growth on MacConkey agar

Question 14

14. A gram-negative coccobacillus was recovered
    on chocolate agar from the CSF of an
    immunosuppressed patient. The organism
    was nonmotile and positive for indophenol
    oxidase but failed to grow on MacConkey
    agar. The organism was highly susceptible to
    penicillin. The most probable identification is:
    A. Acinetobacter spp.
    B. Pseudomonas aeruginosa
    C. Pseudomonas stutzeri
    D. Moraxella lacunata

Answer 14

D. Moraxella lacunata

Question 15

15. Cetrimide agar is used as a selective isolation agar
    for which organism?
    A. Acinetobacter spp.
    B. Pseudomonas aeruginosa
    C. Moraxella spp.
    D. Stenotrophomonas maltophilia

Answer 15

B. Pseudomonas aeruginosa

Question 16

16. A specimen from a 15-year-old female burn
    patient was cultured after débridement, and the
    following results were obtained:
    Oxidase = + Lysine decarboxylase = Neg
    Catalase = +
    Motility = +
    Ornithine decarboxylase = Neg
    Glucose = + for oxidation
    (open tube)
    Arginine dihydrolase = + Maltose = Neg for oxidation
    (open tube)
    Penicillin = Resistant Aminoglycosides =
    Susceptible
    Colistin (Polymixin B) = Susceptible

These results indicate which of the following
organisms?
A. Acinetobacter baumannii
B. Moraxella lacunata
C. Pseudomonas aeruginosa
D. Acinetobacter lwoffii

Answer 16

C. Pseudomonas aeruginosa

Question 17

17. A yellow pigment–producing organism that is
    oxidase positive, nonmotile, and does not grow on
    MacConkey agar is:
    A. Acinetobacter baumannii
    B. Acinetobacter lwoffii
    C. Burkholderia cepacia
    D. Chryseobacterium meningosepticum

Answer 17

D. Chryseobacterium meningosepticum

Question 18

18. Which reagent(s) is (are) used to develop the red
    color indicative of a positive reaction in the nitrate
    reduction test?
    A. Sulfanilic acid and α-naphthylamine
    B. Ehrlich’s and Kovac’s reagents
    C. o-Nitrophenyl-β-D-galactopyranoside
    D. Kovac’s reagent

Answer 18

A. Sulfanilic acid and α-naphthylamine

Question 19

19. A culture from an intra-abdominal abscess
    produced orange-tan colonies on blood agar that
    gave the following results:
    Oxidase = +
    Nitrate reduction = +
    KIA = Alk/Alk (H2S)+
    Motility = + (single polar
    flagellum)
    DNase = + Ornithine decarboxylase = +
    Growth at 42°C = Neg

The most likely identification is:
A. Shewanella putrefaciens
B. Acinetobacter spp.
C. Pseudomonas aeruginosa
D. Chryseobacterium spp.

Answer 19

A. Shewanella putrefaciens

Question 20

20. Chryseobacterium spp. and B. cepacia are easily
    differentiated by which test?
    A. Motility
    B. OF glucose
    C. Oxidase
    D. Cetrimide agar

Answer 20

A. Motility

Question 21

21. A 15-year-old female complained of a severe eye
    irritation after removing her soft-contact lenses.
    A swab of the infected right eye was obtained by
    an ophthalmologist, who ordered a culture and
    sensitivity test. The culture was plated on blood
    agar and MacConkey agar. At 24 hours, growth
    of a gram-negative rod that tested positive
    for cytochrome oxidase was noted. The
    Mueller–Hinton sensitivity plate showed a
    bluish-green “lawn” of growth that proved
    highly resistant to most of the antibiotics tested
    except amikacin, tobramycin, and ciprofloxacin.
    What is the most likely identification?
    A. Burkholderia cepacia
    B. Pseudomonas aeruginosa
    C. Stenotrophomonas maltophilia
    D. Acinetobacter baumannii

Answer 21

B. Pseudomonas aeruginosa

Question 22

22. Which of the listed Pseudomonas spp. is associated
    with the following virulence factors: exotoxin A,
    endotoxins, proteolytic enzymes, antimicrobial
    resistance, and production of alginate?
    A. P. fluorescens
    B. P. putida
    C. P. stutzeri
    D. P. aeruginosa

Answer 22

D. P. aeruginosa

Question 23

23. A 20-year-old horse groomer exhibited a
    “glanders-like” infection. His history indicated
    he had suffered several open wounds on his
    hands 2 weeks before the swelling of his lymph
    nodes. A gram-negative rod was recovered from
    a blood culture that grew well on blood and
    MacConkey agars. Most of the biochemical tests
    were negative, including the cytochrome oxidase
    test. What is the most likely identification?
    A. Burkholderia mallei
    B. Pseudomonas aeruginosa
    C. Pseudomonas stutzeri
    D. Burkholderia pseudomallei

Answer 23

A. Burkholderia mallei

Question 24

24. A Vietnam War veteran presented with a
    “glanders-like” infection (melioidosis). Several
    blood cultures produced gram-negative rods that
    were positive for cytochrome oxidase, oxidized
    glucose and xylose, and grew at 42°C. What is
    the most likely organism?
    A. Stenotrophomonas maltophilia
    B. Burkholderia pseudomallei
    C. Pseudomonas aeruginosa
    D. Acinetobacter spp.

Answer 24

B. Burkholderia pseudomallei

Question 25

25. Cytochrome oxidase-positive, nonfermentative
    gram-negative bacilli were recovered from the
    stool of a cystic fibrosis (CF) patient. The isolates
    produced wet (mucoidy) colonies on blood agar.
    Which identification is most likely?
    A. Acinetobacter spp.
    B. Pseudomonas alcaligenes
    C. Pseudomonas stutzeri
    D. Pseudomonas aeruginosa

Answer 25

D. Pseudomonas aeruginosa