Antimicrobial resistance pattern and molecular epidemiology of ESBL and MBL producing Acinetobacter baumannii isolated from hospitals in Minia, Egypt

Abstract

Introduction: Multidrug resistant (MDR) Acinetobacter baumanii (A. baumannii) strains have emerged as novel nosocomial pathogens threatening patients’ lives, especially in intensive-care units (ICUs). This study aims to determine the prevalence of carbapenemase genes and CTX-M-15 and the resistance pattern of carbapenemase producing isolates.

Methods: A total of 530 clinical specimens were collected from patients suffering from different infections, antibiotic susceptibility test was performed using kirby-bauer disk diffusion method. ESβL production was detected phenotypically by double-disc synergy test (DDST). Carbapenemase production was tested by Modified Hodge Test (MHT). Then, these isolates were tested for MBL detection by disc potentiation test. Carbapenemase encoding genes (VIM, IMP, GIM and SPM, OXA-51, OXA-23 and OXA-143) and CTX-M-15 were tested by polymerase chain reaction (PCR).

Results: Out of 530 samples, 20 bacterial isolates were identified as A. baumannii from different infectious cases, 35% of isolates were ESBL-producers. Eleven isolates were resistant to imipenem (4 isolates) and meropenem (7 isolates). All carbapenem resistant isolates were MHT positive. Nine (45%) isolates were confirmed as A. baumannii by OXA-51 (all were carbapenem resistant). Distribution of IMP, VIM, GIM and SPM, OXA-23, OXA-143 and CTX-M-15 by PCR were 55, 50, 50, 25, 35, 45 and 33% respectively.

Conclusion: The high prevalence of resistance genes and the resistance pattern of the isolates indicate that the detection of ESBLs and MBLs phenotypically and genotypically with the study of the resistance pattern of the isolates is critically important for the surveillance of drug resistance in the hospital environment.