Characterization of β-lactamase- and efflux pump-mediated multiple antibiotic resistance in Salmonella Typhimurium

초록

This study aimed to assess the beta-lactamase- and efflux pump-mediated antibiotic resistance in Salmonella Typhimurium (WT-ST), ciprofloxacin-induced antibiotic-resistant S. Typhimurium (CI-ST), and clinically-acquired antibiotic-resistant S. Typhimurium (CA-ST). The beta-lactamase activities were significantly increased up to 63 mu mol/min/mL in CA-ST and 24 mu mol/min/mL in CI-ST when compared to WT-ST (13 mu mol/min/mL). The highest efflux pump activity was observed in CI-ST and CA-ST, showing more than 45%. The antibiotic susceptibilities of WT-ST, CI-ST, and CA-ST were increased in the presence of beta-lactamase and efflux pump inhibitors. CA-ST showed the highest activity in AcrD, MdtABC, EmrAB, MdtK, and MacAB efflux pumps. The repressed ompF were responsible for the decreased susceptibility of CA-ST to ampicillin (MIC > 512 mu g/mL). This study would provide useful information for better understating of the development of multidrug resistance in association with beta-lactamase and efflux pump activities and designing new antibiotic chemotherapy in combination with inhibitors.

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