Identification of AcrAB-TolC Efflux Pump Genes and Detection of Mutation in Efflux Repressor AcrR from Omeprazole Responsive Multidrug-Resistant Escherichia coli Isolates Causing Urinary Tract Infections

Abstract

Antimicrobial resistance poses a threat in the treatment of infectious diseases in Bangladesh as well as in the world. Multidrug-resistant (MDR) Enterobacteriaceae, the most common cause of one such infectious disease, urinary tract infection (UTI), has contributed to the escalating problem of selecting empiric antibiotics against UTIs. The aim of this study was to investigate the presence of the efflux pump in MDR Escherichia coli isolates from UTI in the North-East region of Bangladesh, to isolate and characterize the AcrAB-TolC efflux pump genes of these locally isolated strains and to do mutation analysis of the efflux pump repressor AcrR gene to understand the AcrAB-TolC efflux pump mechanism. In the presence of omeprazole, an efflux pump inhibitor, every MDR E. coli isolate showed increased susceptibility to at least 1 of the 7 antibiotics investigated, indicating that efflux pump might be involved in their antibiotic resistance. Omeprazole decreased the minimum inhibitory concentration of every antibiotics being investigated by 2- to 8-fold. DNA and the deduced amino acid sequences of the polymerase chain reaction (PCR) products analyzed by bioinformatics tools revealed that the chromosomal AcrAB-TolC and AcrR genes were present in all MDR and antibiotic-susceptible E. coli isolates. However, the deduced amino acid sequences of the amplification refractory mutation system (ARMS) PCR product of the AcrR gene revealed that the substitution of arginine to cysteine at position 45 of AcrR was observed only in the MDR E. coli whose antibiotic susceptibility increased in the presence of omeprazole. Data reported herein support the notion that the increased antibiotic susceptibility of the MDR E. coli isolates in the presence of omeprazole might be due to efflux pump(s) inhibition and the AcrAB-TolC efflux pump might be a contributor to antibiotic resistance when the mutation of arginine to cysteine occurs at position 45 of AcrR.

Efflux Impacts Intracellular Accumulation Only in Actively Growing Bacterial Cells

“…The best-described RND pump is AcrAB-TolC, found in Salmonella enterica serovar Typhimurium and Escherichia coli . As efflux pumps underpin antibiotic resistance in essentially all bacteria of clinical and veterinary importance ( 12 , 13 ), there is ongoing active research into the development of efflux inhibitors to potentiate the action of existing antibiotics.…”

Monitoring of Non-β-Lactam Antibiotic Resistance-Associated Genes in ESBL Producing Enterobacterales Isolates

“…It was observed that the distribution of efflux pumps genes among ESBL producing Enterobacterales isolates were found to be oqxB (67.63%), oqxA (62.59%) and qepA (3.6%), respectively. However, this efflux pump mediated drug resistance mechanism of bacteria can be subdued using various efflux inhibitory molecules [ 24 ], for instance, the susceptibility of antibiotics against multidrug-resistant bacteria (that developed exclusively due to efflux pump mechanisms) can be enhanced in presence of efflux pump inhibitor such as omeprazole [ 25 ]. Further, the genome sequencing analysis of multidrug-resistant strains that might reveal the potential genes that are associated with multidrug efflux pumps and once the genes and gene products are identified, the molecular docking studies that may further help in developing appropriate efflux pump inhibitors.…”

Multidrug Efflux Pump In Relation To Antibiotic Resistance Pattern in Escherichia Coli Strains Isolated From Benha University Hospital

“…Chowdhury et al 30 found that Overexpression of the AcrAB-TolC efflux pump is an intrinsic mechanism of multidrug resistance in Gram-negative bacteria, It can be due to the mutation in AcrR gene which is the repressor of the AcrAB operon system.…”