AcrAB ToLC Efflux pump gene in multi drug resistant Escherichia coli isolated from clinical samples

Abstract

Escherichia coli is one of the most commonly isolated multi drug resistant (MDR) pathogen and has been categorized as the priority pathogen by WHO. Carbapenem is a drug of choice for treatment of E. coli but now resistance of these drugs is spreading due to various mechanism such as the presence of intrinsic mechanism of antibiotic resistance efflux pump gene. Efflux pump has been illustrated as one of the key mechanism of antibiotic resistance crucially in the gram-negative pathogens. Forty-two carbapenem resistant E. coli were isolated from sample specimens of patients of Kathmandu Model Hospital. Cross sectional descriptive study was conducted and the specimens were processed with respective culture media following the antibiotic susceptibility testing according to CLSI guidelines. Phenotypic detection of ESBL and CRE was done using combination disc diffusion and by using cccp respectively. Chromosomal DNA extraction was done using alkaline hydrolysis method. Amplification of AcrAB TolC was carried out by conventional PCR. Out of 2384 samples the infection rate was found to be (21.8%) that is 520 samples showed significant growth of bacteria.E coli being the major isolates constituting of 78% of the total isolates. Bacterial isolates 89.5% were found mostsensitive to PolymixinB and Colistin (99.8%), however was the most and resistant to Amoxycillin (66%). Out of 42 Carbapenem resistant Escherichia coli isolates, AcrA gene was prevalent in 23 (54.7%) of the isolates. AcrB gene in 30 (71.4%) and 31 (73.8%) of the isolates were found to be positive for TolC gene. Out of 403 Escherichia coli isolates, 42 (10.4%) were found to be Carbapenem resistant. Moreover, out of 147 ESBL isolates, 16 isolates (10.9%) were found to be Carbapenem resistant. This research evaluated the minimum inhibitory concentration (MIC) activity of carbapenem, in the presence or lack of the CCCP (25 g/mL) in order to identify the function of the efflux pump in the carbapenem resistant E. coli isolates. The findings demonstrated that most samples had lower MICs in the presence of the pump inhibitor than in the absence of the efflux pump inhibitor. Key Words: Efflux pump, Carbapenem, antibiotic susceptibility test