Loss of outer membrane protein A (OmpA) impairs the survival of Salmonella Typhimurium by inducing membrane damage in the presence of ceftazidime and meropenem

Abstract

Objectives Salmonella enterica serovar Typhimurium is one of the significant non-typhoidal Salmonella serovars that causes gastroenteritis. The rapid development of antimicrobial resistance necessitates studying new antimicrobials and their therapeutic targets in this pathogen. Our study aimed to investigate the role of four prominent outer membrane porins of S. Typhimurium, namely OmpA, OmpC, OmpD and OmpF, in developing resistance against ceftazidime and meropenem. Methods The antibiotic-mediated inhibition of bacterial growth was determined by measuring the absorbance and the resazurin assay. DiBAC4 (Bis-(1,3-Dibutylbarbituric Acid)Trimethine Oxonol), 2,7-dichlorodihydrofluoroscein diacetate (DCFDA) and propidium iodide were used to determine the outer membrane depolarization, reactive oxygen species (ROS) generation and subsequent killing of Salmonella. The expression of oxidative stress-response and efflux pump genes was quantified by quantitative RT–qPCR. HPLC was done to determine the amount of antibiotics that entered the bacteria. The damage to the bacterial outer membrane was studied by confocal and atomic force microscopy. The in vivo efficacy of ceftazidime and meropenem were tested in the C57BL/6 mouse model. Results Deleting ompA reduced the survival of Salmonella in the presence of ceftazidime and meropenem. Massive outer membrane depolarization and reduced expression of oxidative stress-response genes in S. Typhimurium ΔompA hampered its growth in the presence of antibiotics. The enhanced uptake of antibiotics and decreased expression of efflux pump genes in S. Typhimurium ΔompA resulted in damage to the bacterial outer membrane. The clearance of the S. Typhimurium ΔompA from C57BL/6 mice with ceftazidime treatment proved the role of OmpA in rendering protection against β-lactam antibiotics. Conclusions OmpA protects S. Typhimurium from two broad-spectrum β-lactam antibiotics, ceftazidime and meropenem, by maintaining the stability of the outer membrane.

Outer Membrane Proteins and Efflux Pumps Mediated Multi-Drug Resistance in Salmonella: Rising Threat to Antimicrobial Therapy

“…63 Ray et al 64 proposed that the decrease in the expression of ompD, ompC, and ompF upon exposure to altered stress conditions leads to the development of resistance in S. Typhimurium. A similar study was conducted by Chowdhury et al, 65 wherein deletion of ompA, ompC, ompD, and ompF genes in S. Typhi showed significant changes in antibiotic susceptibility toward ceftazidime and meropenem. Some studies have also reported the development of carbapenems resistance due to porin loss in addition to the production of ESBLs in S. Typhimurium.…”

phoP maintains the environmental persistence and virulence of pathogenic bacteria in mechanically stressed desiccated droplets

“…Salmonella typhimurium (STM), one of the leading causes of self-limiting gastroenteritis and diarrhea in humans, 6 , 7 has been used as a model system in the present study. However, the proposed experimental methodology is suitable for investigating any naturally dried bacterial droplets.…”

Defying the odds: Determinants of the antimicrobial response of Salmonella Typhi and their interplay

“…In a bacterium, the resistome refers to all the resistance-associated genes (Wright, 2007). It includes the proto-resistance genes AMR in S. Typhimurium (Chowdhury et al, 2022;Roy Chowdhury et al, 2022).…”

“…Our laboratory has extensively characterized the role of outer membrane protein A (OmpA) in combating innate immune responses and AMR in S . Typhimurium (Chowdhury et al., 2022; Roy Chowdhury et al., 2022).…”