Serotyping clinical isolates of Pseudomonas aeruginosa in relation to infection site antibiotic susceptibility and beta-lactamase production

The present study investigates the association of O-serotype with isolation site, antibiotic resistance, and beta-lactamase production to determine the profiles of Pseudomonas aeruginosa clinical isolates circulating in a Canadian teaching hospital. The most frequently encountered serotypes of Pseudomonas aeruginosa strains isolated from inpatients at H?tel-Dieu de Montréal hospital during the period 1992-1993 were O1, O3, O5, O6, O10, and O11 (9-13%) isolated from pus, urine, sputa and other sources. Serotype O1 was the most sensitive in contrast to serotype O3 which was resistant to virtually all antibiotics tested except to imipenem and quinolone. Of the strains of Pseudomonas aeruginosa, more than 50% with the most encountered serotype produced a high level of beta-lactamase.