Deck 28: Pasteurella and Similar Organisms

Question 1

Although most other clinically relevant gram-negative bacilli are intrinsically resistant to penicillin,it is the drug of choice for infections involving:

A)Sphingomonas paucimobilis.
B)Pseudomonas aeruginosa.
C)Pasteurella multocida.
D)Weeksella virosa.

Answer 1

C
An unusual feature of the organisms considered in Chapter 30 is that most are susceptible to penicillin.Although most other clinically relevant gram-negative bacilli are intrinsically resistant to penicillin,it is the drug of choice for infections involving P.multocida and several other species discussed in this chapter.

Question 2

Which of the following bacterial species is part of animal flora and transmitted to humans during close animal contact,including bites?

A)S.paucimobilis
B)Eikenella corrodens
C)P.multocida
D)W.virosa

Answer 2

C
The majority of the organisms presented in Chapter 30 are part of animal flora and are transmitted to humans during close animal contact,including bites.For most organisms,virulence factors are not recognized and the organisms may be considered opportunistic pathogens that require mechanical disruption of the host's anatomic barriers,such as occurs with bite-induced wounds.Of the organisms listed,P.multocida is the species most commonly encountered in clinical specimens.

Question 3

Quality control should be performed on which two organisms to determine the validity of the nitrate reduction test?

A)Pasteurella aerogenes and Pasteurella dagmatis
B)M.haemolytica and Pasteurella pneumotropica
C)P.multocida and Suttonella indologenes
D)Pasteurella canis and Pasteurella bettyae

Answer 3

C
Only P.multocida and S.indologenes can be used for quality control purposes;P.multocida is nitrate reduction-positive,and S.indologenes is nitrate reduction-negative.All other organisms listed are nitrate-positive.

Question 4

An organism that causes infection as a result of a dog or cat bite was tested for catalase,resulting in a positive reaction.What could be the possible source of the error?

A)The catalase reagent could be expired.
B)This organism is normally negative for catalase;therefore a mutation may have occurred.
C)A false-positive result occurred because of the catalase production of the red blood cells in the 5% sheep blood agar.
D)No error is present.This organism is catalase-positive.

Question 5

Which test is used to differentiate P.multocida from Mannheimia haemolytica?

A)Indole
B)Catalase
C)Nitrate
D)Sucrose