الملخص الإنجليزي
Abstract
Carbapenems are potent antibacterial agents and are used as last resort in treating infections caused by multidrug resistant Gram-negative bacilli. Unfortunately, an alarming increase in carbapenem resistance due to carbapenemase production has been reported among Gram-negative bacilli associated with nosocomial infections. Metallo beta lactamases are an important type of carbapenemase that can hydrolyze a wide variety of B-lactams including penicillins, cephalosporins, and carbapenems. Therefore, the acquisition of theses enzymes by Gram-negative bacilli confers a multidrug resistance profile against many clinically useful B-lactams consequently raising a significant public health concern with respect to antimicrobial chemotherapy, A total of 500 clinical isolates of Pseudomonas aeruginosa (n=200), Escherichia.coli (n=150) and Klebsiella spp. (n=150) recovered from different clinical specimens at SQUH were collected. These isolates were screened for MBL production using imipenem (10ug) and ceftazidime (30ug). Screen positive isolates were subjected to six phenotypic confirmatory tests namely: MHT, DDST, CDT, EDST and EIM test. In addition, PCR was carried out using family specific primers for the screen positive isolates.
Overall, 113/500 (22.6%) clinical isolates were screen positive for MBL (56 P. aeruginosa, 24 Klebsiella spp. and 33 E. coli). Three isolates of K. pneumonia were identified as MBL producers using both the phenotypic tests and PCR assay. MBL was not detected from any of the other screen positive isolates. The three K. pneumonia strains gave positive PCR for the NDM-1 gene. This study found that 22.6% of clinical isolates collected from SQUH were screen positive for MBL production. In addition, the present study established that MHT MCA gave a better performance in the detection of carbapenemase producing isolates in comparison to MHT-MHA. This study also found that all the phenotypic tests were equally efficient in the detection of MBL producers as all these tests have detected the same 3 isolates as MBL positive and were in concordance with the results of PCR.
