An Oxidase Test Was Performed on Two Organisms for Quality

Multiple Choice

An oxidase test was performed on two organisms for quality control purposes.Pseudomonas aeruginosa and Stenotrophomonas maltophilia tested positive and negative,respectively.Which of the following statements explains this discrepancy?

A) The oxidase reagent is most likely expired.
B) The organisms are most likely old and therefore are not properly reacting.
C) These organisms are poor choices for quality control purposes;both are oxidase-negative organisms.
D) No discrepancy is present.The correct results are obtained.