Abstract
The aims of this study were to determine the antibiotic resistance patterns in Pseudomonas aeruginosa species isolated from three hospitals and to determine the prevalence of metalo-β-lactamase (MBL) bla-VIM encoding gene. A total of 134 clinical isolates of P. aeruginosa were collected from different pathological specimens over 12 months. Phenotypic characterization was performed using EDTA and MBL E-test strip. MBL producing P. aeruginosa isolates were further screened for the bla-VIM gene by polymerase chain reaction. All isolates were resistant to the antibiotics tested including aminoglycosides, fluoroquinolones and carbapenems, but susceptible to colistin. Phenotypic screening for MBL production indicated that 31.3% were MBL positive. Imipenem-resistant isolates (MIC of> 8 µg/ml)(51/73; 71.2%) were MBL positive; the majority (34/42; 81%) were isolated from the burns unit. VIM-positive isolates (20.1%) had significantly (P≤ 0.05) higher proportions of resistance to certain antibiotics carbapenems, aminoglycosides, fluoroquinolones, cefepime and piperacillin-tazobactam compared to VIM-negative isolates. The proportion of MDR isolates was 53%, mainly obtained from patients in ICU patients with burn and significantly higher (P= 0.003) among VIM producers. It was observed that all isolates that were positive for MBL E-test and EDTA had the bla-VIM gene and were MDR isolates. These were found only among isolates from ICU patients with burns.