8.3 Nonfermentative Bacili

Question 1

What are the most appropriate screening test to presumptively differentiate and identify the nonfermentative gram-negative bacilli (NFB) from the Enterbacteriaceae?
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

Presumptive test used for identification of 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 (EMB) agars, lysine decarboxylation, catalase
C. Growth on macConkey, EMB, and XLD agars, and motility
D. Growth on mannitol slat agar and flagellar stain

Answer 2

A. Oxidase, oxidation-fermentation (OF) glucose (open), OF glucose (sealed), motility, pigment production
B. Growth on blood agar plate (BAP) and eosin-methylene (EMB) agars, lysine decarboxylation, catalase

Question 3

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

Answer 3

D. Mannitol, nitrate reduction, growth at 42C

Question 4

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

Answer 4

A. Oxidase, motility, NO3 reduction

Question 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

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

Answer 6

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

Question 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

A nonfermenter recovered form an eye wound is oxidase positive, motile with polas monotrichous flagell, and grows at 42C. 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

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

Which biochemical test 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

The following results were obtained form a pure culture of gram-negative rods recovered form the pulmonary secretions of a 10-year-old cystic fibrosis patient with pneumonia:
-Oxidase=+
-Glucose OF (open)=+
-Pigment=Red (nonfluorescent)
-Growth at 42C=+
-Motility =+
-Gelatin hydrolysis=+
-Arginie dihydrolase=+
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

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

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

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

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

Answer 15

B. Pseudomonas aeruginosa

Question 16

A specimen from a 15-year old female burn patine was cultured after debridement, and the following results were obtained:
-Oxidase=+
-Catalase=+
-Ornithine decarboxylase=Neg
-Arginine dihydrolase=+
-Penicillin=Resistant
-Colistin (Polymixin B)= Susceptible
-Lysine decarboxylase=Neg
-Motility=+
-Glucose=+ for oxidation (open tube)
-Maltose=Neg for oxidation (open tube)
-Aminoglycosides=Susceptible
These results indicate which of the following organism?
A. Acinetobacter baumannii
B. Moraxella lacunata
C. Pseudomonas aeruginosa
D. Acinetobacter lwoffi

Answer 16

C. Pseudomonas aeruginosa

Question 17

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

Answer 17

D. Chryseobacterium meningosepticum

Question 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 a-naphthylamine
B. Ehrilich’s and Kovac’s reagents
C. o-Nitrophenyl-B-D-galactopyranoside
D. Kovac’s reagent

Answer 18

A. Sulfanilic acid and a-naphthylamine

Question 19

A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar that gave the following results;
-Oxidase=+
-KIA=Alk/Alk (H2S)
-DNase=+
-Growth at 42C=Neg
-Nitrate reduction=+
-Motility=+ (single polar flagellum)
-Ornithine decarboxylase=+
The most likely identification is:
A. Shewanella putrefaciens
B. Acinetobacter spp.
C. Pseudomonas aeruginosa
D. Chryseobacterium spp.

Answer 19

A. Shewanella putrefaciens

Question 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

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 gram0negative 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. Stenotrophomas maltophilia
D. Acinetobacter baumannii

Answer 21

B. Pseudomonas aeruginosa

Question 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

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 rom 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

A Vietnam War veteran presented with “glanders-like” infection (melioidosis). Several blood cultures produced gram-negative rods that were positive for cytochrome oxidase, oxidized glucose and xylose, and grew at 42C. 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

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