A Systematic Review: The Source of Antimicrobial Resistance Pathogenic Bacteria on Slaughtered Meat, Cross-contamination or Self-contamination?

Abstract

Slaughtered meat has been identified as one of the major vehicles for forming antimicrobial resistance (AMR). It is still believed that AMR pathogens introduced by overusing antimicrobials in the breeding industry are directly brought in from farm animals. This disregards however the fact that many gut pathogens do not settle on muscle parts; the presence of gut pathogens on muscle products does not directly correlate to farm feeding. To investigate whether the source of AMR bacteria on slaughtered meat was cross-contamination or self-contamination, many peer-reviewed publications were studied to assess if the observational studies focused on AMR pathogenic bacteria association between farms and slaughterhouses or the contamination on the slaughter line. Using PubMed, 1919 publications on AMR bacteria in farms and slaughterhouses were collected. The 1650 papers were assembled (269 of them being repeated). From these, 92 were included in the study: 29 surveillance studies reported that AMR bacteria in slaughtered products were related to farm sources; 63 papers reported cross-contamination in the slaughter process at a significant level. Several crucial points were highlighted, including 1) the scalding, de-feathering and evisceration in the broiler slaughter line; 2) residential flora, evisceration, inappropriate meat inspection, conveyor belts, splitting, equipment in the boning hall, holding, chilling, and lairage contamination in the pig slaughter line. In this study, AMR bacteria of the two sources were genetically related. However, the majority of cases still resulted from cross-contamination (29% to 98.48%). This means that major sources of gut AMR bacteria on slaughtered meat were cross contaminated during the slaughter process.