Comparative evaluation of three testing methods for detection of mediated resistance MBL in pseudomonas aeruginosa isolates

Abstract

Metallo – β – lactamase (MBL) producing Pseudomonas aeruginosa have been reported to be important cause of nosocomial infections. The appearance of MBL genes and their spread among bacterial pathogens is a matter of concern with regard to the future of antimicrobial therapy. The present study was undertaken to determine which method is better to use in laboratory for detecting MBL producing P. aeruginosa. A total of 182isolates of P. aeruginosa from human and animals, 125 from human and 57 from animals, (burns, pus, urine, blood cultures, etc.), collected between 2013 and 2015 were subjected to susceptibility testing against various antibiotics by disc diffusion test according to Clinical and Laboratory Standards Institute (CLSI) guidelines 2015. Imipenem resistant isolates were selected for the detection of MBL production by E-test strips for screening MBL, double disc method (IPM and IPM+EDTA) and EDTA solution application on microcaps IPM. The positive results have been based on inhibition zone around imipenem discs impregnated with EDTA as compared to those without EDTA confirmed MBL production and for E-test strips the strains were positive those that have developed around area with EDTA solution. The double disc method (IPM and IPM+EDTA is most effective way to use in laboratory to determine early producer P. aeruginosa MBL, having 2 advantage: first is the low cost for materials (MH agar and microcaps) and the technique is very easy to be applied.