What test can differentiate Pseudomonas aeruginosa from other nonfermentative gram-negative bacilli?

The oxidase test is a crucial method for differentiating Pseudomonas aeruginosa from other nonfermentative gram-negative bacilli. Pseudomonas aeruginosa is oxidase-positive, meaning it produces cytochrome c oxidase, an enzyme involved in the electron transport chain. This enzyme catalyzes the transfer of electrons from reduced substrates to molecular oxygen. In contrast, nonfermentative organisms that do not produce this enzyme will yield a negative result in the oxidase test.

The test involves applying a reagent to a colony from an agar plate; if the colony turns purple, it indicates a positive result for cytochrome c oxidase production. This distinct characteristic helps microbiologists swiftly identify Pseudomonas aeruginosa during microbial investigations, especially in clinical laboratories where accurate identification is essential for appropriate treatment.

While the urease test, indole test, and string test have their respective purposes in identifying different bacterial species, they do not serve as reliable methods for distinguishing Pseudomonas aeruginosa from nonfermentative gram-negative bacilli.