Detection and classification of integron in Pseudomonas aeruginosa isolated from patients registered at Thammasat Chalermprakiat hospital

Pseudomonas aeruginosa is one of the most important nosocomial pathogens associated with multiple drug resistance that acquires through the transmissible genetic elements, integron. In this study, integron was detected and classified from P. aeruginosa isolated from patients registered at Thammasat Chalermprakiat hospital during January- December 2008 by using Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP). Integron was found as 3.5% (18/509) of P. aeruginosa isolates and all of them were class 1 integron. The percentage of antibiotic resistant strains found in integron positive isolates was 66.7% (12/18) and 83.3% (10/12) of these strains correlated with multiple drug resistance with similar profile to imepenem, ceftazidime and piperacillin. The other 33.3% (6/18) of integron positive isolates were susceptibility strains. This was possibly due to no insertion of these gene cassettes or incomplete insertion. However, the resistant profiles were also found in integron-negative isolates that might be resulted from limitation of detection method due to the evolution of integrase gene, or from other factors.