A gram-negative rod that tests positive for oxidase and produces a distinctive bluish-green pigment has been isolated from a burn wound infection. This bacterium is sensitive to gentamicin, ticarcillin, and tobramycin, but shows resistance to most other antibiotics. Which of the following organisms is the most probable cause?

Explanation

The organism described is Pseudomonas aeruginosa, characterized by its oxidase positivity, gram-negative rod shape, and production of a bluish-green pigment called pyocyanin. It commonly infects burn wounds and exhibits resistance to many antibiotics, but remains susceptible to agents like gentamicin, ticarcillin, and tobramycin. Other listed bacteria do not produce this pigment or share this antibiotic sensitivity profile.