<p>Evaluation of efflux pump activity of multidrug-resistant <em>Salmonella</em> Typhimurium isolated from poultry wet markets in India</p>

Abstract

Introduction: Salmonella enterica subspecies enterica serovar Typhimurium ( S. Typhimurium ) is one of the major cause of foodborne zoonoses in humans. Poultry acts as a reservoir for S . Typhimurium without showing clinical signs and has become a source of infection to humans. Besides, it also became a source of multidrug-resistant (MDR) strains of S . Typhimurium. Methods: In the present study, we have isolated 9 S . Typhimurium from 503 samples from environmental sources of poultry wet markets in the Kadapa District of Andhra Pradesh, India. The role of efflux pump activity in antibiotic resistance was evaluated by ethidium bromide cartwheel test and efflux pump inhibition assay. Results: Eight out of nine isolates were resistant to two or more classes of antibiotics. The efflux pump activity of these isolates by ethidium bromide cartwheel method revealed that 66.6% isolates had shown evidence of pronounced efflux activity. The zone of inhibition (ZOI) of resistant antibiotics for each isolate was estimated in the presence or absence of 25 µg/mL of PAβN. Overall, cephalosporins (cefazolin, cefamandole, and cefaclor), kanamycin, polymyxin-B, piperacillin, and imipenem showed significant increase (≥2 mm) of ZOI, indicating the role of efflux pumps for efflux of these drugs. A maximum of 4 antibiotics among EtBr efflux pump positive isolates and 2 antibiotics among EtBr efflux pump negative isolates showed increased ZOI in the presence of PAβN. Conclusion: The results indicate that efflux pumps of MDR S . Typhimurium may contribute to resistance for at least one antibiotic, even in EtBr cartwheel test negative isolates.

Tannic Acid-Stabilized Silver Nanoparticles Used in Biomedical Application as an Effective Antimelioidosis and Prolonged Efflux Pump Inhibitor against Melioidosis Causative Pathogen

“…Ethidium bromide (EtBr) has been reported as the substrate in many efflux pump systems in both Gram-positive and Gram-negative bacteria. Thus, it has been used to intrinsically evaluate efflux pump activity in Escherichia coli (E. coli) , Staphylococcus aureus (S. aureus) , Klebsiella pneumoniae (K. pneumonine) , Pseudomonas aeruginosa (P. aeruginosa) and Burkholderia species [ 53 , 54 , 55 ]. Bacteria could develop resistance by using transport proteins involved in the extrusion of antibiotics out of the cell.…”

“…In the bacterial cell, ethidium bromide (EtBr, Sigma-Aldrich) has been recognized as a substrate for many efflux pump systems. The cartwheel method is a simple phenotypic test to detect the efflux pump activity of bacteria in pumping EtBr out of the cell and was used in this study according to the procedure of Anbazhagan, et al [ 54 ]. Muller Hinton agars containing EtBr in the range of 0–2.5 µg/mL were freshly prepared on the day of the experiment.…”

Evaluation of efflux pump activity and biofilm formation in multidrug resistant clinical isolates of Pseudomonas aeruginosa isolated from a Federal Medical Center in Nigeria

“…The Ethidium Bromide (EtBr)-agar cartwheel method as described by Anbazhagan et al [ 16 ] was used to determine the efflux pump activity of isolates. Briefly, bacterial cell suspension of approximately 10 6 cells per mL was streaked on Mueller–Hinton agar plates containing 0 mg/L, 0.5 mg/L, 1 mg/L, 1.5 mg/L, and 2 mg/L concentrations of EtBr and incubated for 24 h at 37 °C.…”

Efflux pump inhibitory activity of biologically synthesized silver nanoparticles against multidrug‐resistant Acinetobacter baumannii clinical isolates

“…To phenotypically detect efflux pumps in MDR A. baumannii strains, the ethidium bromide (EtBr) cartwheel method was used [27]. Briefly, Muller–Hinton agar (MHA) plates containing EtBr were prepared.…”