Deck 21: Achromobacter, Rhizobium, Ochrobactrum, and Similar Organisms

Question 1

The natural habitat of Ochrobactrum spp.can best be described as the:

A)mucous membranes of animals.
B)gastrointestinal tract of humans and other animals.
C)natural environment.
D)genitourinary tract of animals.

Answer 1

C
Most of the organisms discussed in Chapter 22 exist in the environment.As environmental organisms,these bacteria are rarely encountered in human specimens or infections.When they are encountered,they are found on contaminated medical devices or are isolated from patients who are immunocompromised or otherwise debilitated.

Question 2

Which organism is a nonlactose-fermenter that oxidizes glucose and xylose and also morphologically resembles colonies of Enterobacteriaceae?

A)CDC group Ic
B)O.anthropi
C)S.putrefaciens
D)A.xylosoxidans

Answer 2

B
Morphologically,O.anthropi resemble colonies of Enterobacteriaceae,only smaller,and is a nonlactose-fermenting organism.

Question 3

Which of the following organisms has clear colonies on MacConkey agar,oxidizes glucose and xylose,and has the ability to hydrolyze esculin?

A)Alcaligenes xylosoxidans
B)Paracoccus yeei
C)Rhizobium radiobacter
D)Shewanella putrefaciens

Answer 3

C
R.radiobacter is the only organism listed that has these characteristics and hydrolyzes esculin.

Question 4

The reservoir for O.anthropi is:

A)environment only,not human flora.
B)animal oral and respiratory flora.
C)environment,cold climates.
D)environment and human flora.

Question 5

Which two organisms should be used to determine the validity of the nitrate reduction test?

A)Ochrobactrum and Alcaligenes
B)Psychrobacter and Rhizobium
C)CDC group Ic and CDC group O-3
D)CDC group OFBA-1c and Shewanella

Question 6

Although validated susceptibility testing methods do not exist for this group of organisms,in vitro data suggest that certain cephalosporins and aminoglycosides are effective against which one of the following groups of organisms?

A)O.anthropi
B)S.putrefaciens
C)P.yeei
D)R.radiobacter

Question 7

The most common type of infection caused by both R.radiobacter and Ochrobactrum anthropi is:

A)peritonitis.
B)endocarditis.
C)meningitis.
D)bacteremia.

Question 8

A patient with an indwelling catheter tip began spiking a fever of 39°C.The site of the catheter was inflamed and red.The catheter tip was cultured,and the following organism was isolated: a nonlactose-fermenter on MacConkey agar;a glucose,xylose,and mannitol oxidizer with the ability to hydrolyze esculin.This organism is most likely which one of the following?

A)CDC group EF-4b
B)S.putrefaciens
C)R.radiobacter
D)P.yeei

Question 9

Which nonlactose-fermenting organism,that rarely causes human infection,grows poorly at 35°C;however,grows optimally between 20°C and 25°C?

A)Psychrobacter pulmonis
B)A.xylosoxidans
C)R.radiobacter
D)S.putrefaciens