Epidemiology and Antibiotic Resistance of Staphylococci on Commercial Pig Farms in Cape Town, South Africa

Abstract

<title>Abstract</title> Nasal swabs were collected from 143 apparently healthy pigs and 21 pig farm workers, and 45 environmental swabs of feed and water troughs, from two commercial pig farms in the Western Cape, South Africa. Staphylococci were isolated, identified using mass-spectrometry, and antimicrobial susceptibility testing and Illumina whole genome sequencing were performed. One hundred and eighty-five (185) S<italic>taphylococcus </italic>spp. isolates were obtained, with <italic>Mammalicoccus sciuri </italic>(<italic>n </italic>= 57; .31%) being the most common, followed by <italic>S. hyicus </italic>(<italic>n </italic>= 40; 22%) and <italic>S. aureus </italic>(<italic>n </italic>= 29; 16%). <italic>S. epidermidis</italic> was predominantly seen in the farm workers (n=18; 86%). Tetracycline resistance was observed across all species, with rates ranging from 67% to 100%. Majority <italic>of M. sciuri</italic> isolates (<italic>n </italic>= 40; 70%) were methicillin resistant, with 78% (<italic>n </italic>= 31) harbouring <italic>mecA</italic>. <italic>M. sciuri </italic>isolates had genes/elements which were associated with SCC<italic>mec</italic>_type_III (3A) &amp; SCC<italic>mec</italic>_type_VIII(4A) and were mostly observed in ST61 strains. ST239 strains were associated with SCC<italic>mec</italic>_type_III(3A). High rates of tetracycline resistance were identified among staphylococci in the pig farms in Western Cape, South Africa. This highlights the need for policy makers to regulate the use of this antibiotic in pig farming.