Miscellaneous Gram Negative Rods

Question 1

A wound culture interim report:
Many non-lactose fermenting gram-negative rods, oxidase positive
This is most consistent with:
A) Enterobacter
B) Pseudomonas
C) Acinetobacter
D) Stenotrphomonas

Answer 1

B- Pseudomonas

All of the listed organisms are opportunistic pathogens that can cause wound infections.
Enterobacter is usually a lactose-fermenting gram-negative rod and is oxidase negative (it is an Enterobacteriaceae)
Acinetobacter and Stenotrophomonas are oxidase negative.
Pseudomonas aeruginosa is the only listed organism that is oxidase positive.

Question 2

The drug of choice to treat Stenotrophomonas maltophilia infections is:

Answer 2

Trimethoprim/Sulfamethoxazole

Question 3

Which of the following is most likely to put a patient at risk of developing an infection with Pseudomonas, Stenotrophomonas, and Acinetobacter?

Answer 3

being on broad-spectrum antibiotics while hospitalized

Question 4

An organism causing burn wound infections, corneal infections that can lead to blindness, and serious lung infections in cystic fibrosis patients is most consistent with:

Answer 4

Pseudomonas aeruginosa

Question 5

An organism that is multi-drug resistant and implicated in serious wound infections in military personnel in Iraq is most consistent with:

Answer 5

Acinetobacter baumannii

Question 6

What organism has a grape smell and green pigment on culture

Answer 6

Psuedomonas

Question 7

Where is pseudomonas most likely found?

Answer 7

Ubiquitous- Moist environments (soap, sink, pools, ventilator, dialysis eq); Requires O2 for growth

Question 8

Most commonly isolated non-lactose fermenting GNR.

Answer 8

Pseudomonas sp.

Question 9

T/F: Pseudomonas is a part of normal flora.

Answer 9

False: Usually not part of normal flora

Question 10

T/F: Pseudomonas • Secretes enzymes/toxins that destroy tissue

Answer 10

True

Question 11

T/F: Pseudomonas resistance to Penicillin, ampicillin, 1&2nd gen Cephalosporins. Many beta-lactams

Answer 11

True

Question 12

What can lead to corneal ulcers leading to eye loss if not promptly treated?

Answer 12

Infection of Pseudomonas aeruginosa

Question 13

On what type of media and how long will is take to grow Pseudomonas aeruginosa?

Answer 13

Routine media w/i 18-24 hours

Question 14

What is 2nd most common non-lactose fermenter and Opportunistic- wound infx (Iraq), nosocomial (ventilator/cath)

Answer 14

Acinetobacter sp.

Question 15

Drug of choice for Acinetobacter infections

Answer 15

Carbapenems (resistance increasing)

-Colistin and Polymyxin B

Question 16

What type of media and how long to grow for Acinetobacter sp. in lab?

Answer 16

Routine media at 24-72 hours. Plump GNR in pairs

Question 17

Stenotrophomonas grows within:

Answer 17

24-48 hours on routine culture media

Question 18

Extended use of broad-spectrum antibiotics puts a patient at risk of developing an infection with:

a) Acinetobacter sp.
b) Stenotrophomonas sp.
c) Pseudomonas auruginosa
d) All the above

Answer 18

D

Question 19

A preliminary culture report:
Many non-lactose fermenting GNR, oxidase negative is consistent with:
A) Acinetobacter, Proteus, Stenotrophomonas
B) E. Coli, Pseudomonas, Neisseria
C) Corynebacterium, mycobacterium, bacillus

Answer 19

A