Abstract:
The global antibiotic resistance crisis, driven by overuse and misuse of antibiotics, is multifaceted. This study aimed to assess the microbiological and genetic characteristics of raw retail pork
meat through various methods, including the isolation, antibiotic susceptibility testing (AST), wholegenome sequencing (WGS) of selected indicator bacteria, antibiotic residue testing, and metagenomic
sequencing. Samples were purchased from 10 pre-selected retail stores in Gauteng, South Africa. The
samples were aseptically separated, with portions sent to an external laboratory for isolating indicator
bacteria and testing for antibiotic residues. Identification of the isolated bacteria was reconfirmed
using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF
MS). AST was performed using the Microscan Walkaway system (Beckman Coulter, Brea, CA, USA).
WGS and metagenomic sequencing were performed using the Illumina NextSeq 550 instrument (San
Diego, CA, USA). The isolated E. coli and E. faecalis exhibited minimal phenotypic resistance, with
WGS revealing the presence of tetracycline resistance genes. Both the isolated bacteria and meat
samples harboured tetracycline resistance genes and the antibiotic residue concentrations were within
acceptable limits for human consumption. In the metagenomic context, most identified bacteria
were of food/meat spoilage and environmental origin. The resistome analysis primarily indicated
beta-lactam, tetracycline and multidrug resistance genes. Further research is needed to understand
the broader implications of these findings on environmental health and antibiotic resistance.
