| المستخلص: |
Pseudomonas aeruginosa is one of the causative agents of hospital-acquired infections, especially in burn patients, which is not only due to its high prevalence and severity but also because of its intrinsic and acquired resistance to antibacterial drugs, both of which complicate antipseudomonal chemotherapy. The carbapenems have been the drug of choice for the treatment of infections caused by penicillin or cephalosporin resistant Gram-negative bacilli. However, carbapenem resistance has been observed frequently in non fermenting bacilli P. aeruginosa. High resistance rates to antimicrobials used in the treatment of P. aeruginosa is infections have been reported worldwide, particularly in developing countries including Libya. The problem worst by emergence of Metallo-β-lactamases (MBLs) that mediate resistance to β-lactam drugs among P. aeruginosa organism in recent years. However, there is little information on the detection of MBLs genes in P. aeruginosa is from patients in the Arab countries using polymerase chain reaction (PCR) and in Libya such information is lacking. This study aimed to determine the antibiotic resistance pattern in P. aeruginosa species isolated from Tripoli hospitals: Burn and Plastic Surgery Center (BPSC) and Tripoli Medical Center (TMC), and evaluate the prevalence of MBLs bla-VIM gene using polymerase chain reaction (PCR). A total of 134 (71 male, 63 female) non duplicate nonconsecutive clinical isolates of P. aeruginosa were collected from different pathological specimens over 12 months from April 2013 to March 2014. Isolated organisms were identified to the species level and tested for their susceptibility to a variety of antimicrobial agents by the BD Phoenix Automated System. Phenotypic characteristic was performed using EDTA and MBL E-test strip. Then, MBL producing P. aeruginosa isolates were screened for the bla-VIM gene using PCR. The results of antibiotic susceptibility testing revealed that the isolates were resistant to tested antibiotics with different degrees, but all isolates were sensitive to colistin. Phenotypic screening for MBL production found that 31.3% are MBL positive. Imipenem-resistant (MIC of >8 μg/ml) (71.2%) were MBL positive; the majority (70.8%) of these strains were isolated from burn patients. Overall the rate of MDR was 53% and mainly associated with ICU burn patients and significantly higher among VIM producers. VIM-positive isolates (20.1%) had significant higher rates of resistance to certain antibiotics such as carbapenems, aminoglycosides, fluoroquinolones, cefepime and piperacillin-tazobactam compared to VIM-negative isolates. It was observed that all isolates that simultaneously positive for MBL E-test and EDTA was found to exhibit blaVIM gene and proved to be MDR and was only detected from burn ICU. The high rate of antibiotic resistance among P. aeruginosa strains expressing blaVIM gene are very alarming and can be responsible for serious infections especially burn patients. Therefore, guidelines and appropriate infection control measures are needed to prevent such infections among patients.
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