Investigation Of Colistin Resistance In Clinical Salmonella enterica subsp. enterica Isolates In Greece

Abstract

Salmonella enterica subsp. enterica is a rod shaped, Gram negative bacterium. The public health importance of S. enterica subsp. enterica stems from its ability to cause salmonellosis in humans and animals. Effective treatment with the appropriate antimicrobial agent is crucial for managing the disease. Antimicrobial resistance (AMR) is the ability of bacteria, viruses, fungi, and parasites to withstand the effects of medicines that are used to treat infections. Salmonella, along with other bacteria, have developed resistance against various classes of antimicrobials. In this frame, colistin, a polycationic peptide antimicrobial, is re-introduced in medicine to treat multidrug resistant bacteria. Of major concern is the global emergence of colistin resistant bacteria, which may also bear mobi le colistin resistance (mcr) genes in plasmids, thus enabling the horizontal transmission of colistin resistance between different species of bacteria. The objectives of this study were: i) the estimation of the Minimal Inhibitory Concentration (MIC) of co listin in 120 Salmonella enterica human isolates using a commercial kit based on the broth microdiluton method (BDM) and ii) the investigation of the genetic basis of colistin resistance in Salmonella enterica isolates by employing two standardized and validated conventional multiplex PCR protocols for the detection of mcr 1-5 and mcr 6-9 plasmid borne genes. Results showed that 10% of the isolates were colistin resistant and were predominantly belonging to S. Enteritidis serotype, revealing that the epidemiology is similar to other European countries . Mcr genes were not detected in any of the resistant strains. To comprehensively address the challenge of AMR against colistin, it is imperative to enhance our und erstanding of emerging resistance and the distribution of mcr genes in Salmonella isolates from Greece. This can facilitate the adoption of surveillance strategies and a One Health approach to manage this emerging threat.