Detection and characterization of multidrug resistance and extended-spectrum-beta-lactamase-producing (ESBLS) Pseudomonas aeruginosa isolates in teaching hospital

Pseudomonas aeruginosa is the most common pathogen causing nosocomial infections. The objective of this study was to investigate the extended-spectrum-beta-lactamase (ESBLs) producing and multidrug resistance of hospital isolates of P. aeruginosa and to determine the presence of several resistance genes. A total of 86 isolates of P. aeruginosa were collected from teaching hospital in Kashan, Iran. Susceptibility to eight antimicrobial agents was performed by disk diffusion method. ESBL-phenotypic detection was carried out by double-disk synergy test; and the presence of the genes encoding ofbla(TEM), bla(SHV), bla(CTX-M), bla(OXA) and bla(GES)-like genes was studied by polymerase chain reaction. The prevalence of ESBLs was 8.1%. The presence of genes encoding ESBLs was confirmed in seven isolates, comprising seven bla(GES-2), onebla(SHV-1), one bla(SHV-5) and one bla(CTX-M-1) genes. P. aeruginosa demonstrated the highest resistance rate to piperacillin (38.4%), 67.5% of isolates were sensitive to imipenem whereas 32.5% were MDR (resistant to three or more classes of antibiotics). A multidrug-resistant (MDR) phenotype occurred frequently in P. aeruginosa. bla(GES-2), which compromises the efficacy of imipenem detected in all of seven ESBL-producing P. aeruginosa strains. Proper infection control practices and barriers are essential to prevent spreading and outbreaks of ESBL-producing and MDR P. aeruginosa in our teaching hospital.   Key words: Pseudomonas aeruginosa, extended-spectrum-beta-lactamase, multidrug-resistant.