Prevalence and Transmissibility of Antimicrobial Resistance Genes in Heat Treated Milk

Abstract

The main objectives of this study were to examine the efficiency of the current practiced heat treatments in dairy sector on the persistence, expression and in-vitro transmissibility of the plasmid mediated ARGs in heat treated milk. Survey the prevalence of different ARGs on both farm and commercial heat-treated milk. Evaluating different heat treatments as a potential predisposing cause for inducing VBNC state in dairy microbiota. To achieve those objectives, we proposed the following aims: 1: Quantify the copy number of different plasmid mediated ARGs after different heat treatments. 2: Examine the expression and transmissibility of those ARGs to another microorganism after heat treatments. 3: Survey the prevalence of different plasmid mediated ARGs in both farm and commercial levels. 4: Evaluate the effect of current practiced heat treatments in dairy sector on the creation of VBNC state in dairy microbiota. The first in-vitro part of the study was conducted to assess the efficacy of heat treatments practiced by dairy industry (pasteurization & UHT) and retailers on the survival and the behavior of two different staphylococcal microorganisms (S. aureus (ATCC® BAA-2312™) and S. sciuri) and the persistence and transmissibility of their plasmid mediated ARGs (blaZ, mecC & tetK ). Through molecular quantification of their copy numbers before and after different heat treatments in both milk as a biological media and Tris-EDTA (TE) buffer as non-biological media, over three weeks storage during refrigeration +4℃.