A microbiologist is reading the plates from a sputum culture. The culture is from a patient with cystic fibrosis. One organism dominates the blood agar, chocolate, and MacConkey plates. The MacConkey plate shows an organism with a green pigment and a metallic sheen. The probable identification for this organism is
A) Pseudomonas aeruginosa.
B) Serratia marcescens.
C) Chromobacterium violaceum.
D) Prevotella melaninogenica.

Question

Quizplus · Accepted Answer

Pseudomonas aeruginosa is a common cause of lung infections in patients with cystic fibrosis and is known to dominate blood agar, chocolate, and MacConkey plates. It also produces a green pigment and metallic sheen on MacConkey agar. Serratia marcescens can also produce a green pigment on MacConkey agar, but it is less commonly associated with lung infections in cystic fibrosis patients. Chromobacterium violaceum and Prevotella melaninogenica are not commonly associated with cystic fibrosis lung infections.

A Microbiologist Is Reading the Plates from a Sputum Culture