Prevalence of Metallo-β-Lactamaseproducing Pseudomonas aeruginosaisolated from different clinical samples in Baghdad province

Abstract

Background: Metallo beta lactamase(MBL) producing Pseudomonas aeruginosahave been reported to be an important nosocomialinfections.Pseudomonas aeruginosa is a leading cause of nosocomial infections, giving risetoa wide range of life-threatening conditions. Its intrinsic & acquired resistance to many antimicrobial agents and its ability to developmultidrug resistance imposes a serious therapeutic problem. Materials and Methods: A total of 75 P.aeruginosaisolates were isolated from different clinical samples in some public & private hospitals in Baghdad city during the period from April to August 2011.Bacterial identification was done using conventional cultural & chemical methods &and VITEk 2 cards for identification (GN), while the minimum inhibitory concentration (MIC) testing was performed using disk diffusion,E-test for Imipenem& Meropenem(oxoid, UK) & (AST-GN30)cards in VITEK 2 automated system(bioMérieux, , France). Each P.aeruginosa isolates showed resistance to Carbapenems(Imipenem& Meropenem) were subjected to Imipenem-EDTA combined disc synergy test (CDST) to investigate the production of MBL(confirmative test) Results:Out of 75 P.aeruginosa isolates,16 (21.3%) were grow on MacConkey agar supplemented with Meropenem4mg/L (MMAC),this method used as screening test, The MIC of different antibiotics was performed on these isolates using different methods(VITEK2AST-GN30,Imipenem&Meropenem E-test) showed that 6 (37.5%) isolates were Carbapenem resistant MIC ≥16μg/ml,while 4(25%) pseudomonas isolates appear to be MBL producer usingImipenem-EDTA combined disc synergy test(CDST). Discussion: MBL mediated carbapenemresistance in P. aeruginosa is a cause for concern in thetherapy of critically ill patients. The MBL producing P. aeruginosa isolates were more resistant to various antimicrobial agents. This result suggests that MBL producing isolates in hospitals may cause serious infections that illustrated when these strains were responsible for a nosocomial outbreak.The findings strongly suggest that there is a need to track the detection of MBL producers and that judicious use of carbapenems is necessary to prevent the further spread of these organisms. Conclusion: The prevalence of multi-drug resistant P.aeruginosa isolates especially Carbapenem resistant bacteria was increased in Baghdad province.Phenotypic characterization of MBLs provide information about the prevalence of MBLs producing P. aeruginosa in Baghdad.