Detection and molecular characterisation of methicillin-resistant Staphylococcus aureus isolated from raw meat in the retail market

Abstract

Objectives: This study aimed to detect and characterise methicillin-resistant Staphylococcus aureus (MRSA) from retail meat in the Czech Republic.

Methods: Isolates were identified by PCR detection of the S. aureus-specific fragment Sa442 and mecA gene. spa typing, MLST, detection of genes encoding staphylococcal enterotoxins, Panton-Valentine leukocidin (pvl), exfoliative toxins A and B (eta and etb), toxic shock syndrome toxin (tst) and staphylokinase (sak), detection of φSa3 prophage and antimicrobial susceptibility testing were performed.

Results: Of 65 raw meat samples examined (poultry, beef, pork and rabbit), 23 (35.4%) were positive for MRSA. Twelve positive samples originated from poultry (12/33; 36.4%), while the remaining eleven came from pork (9/9; 100%) and pork/beef mixed minced meat (2/5; 40.0%). Eight spa types belonging to five different sequence types (STs) were identified. ST398 was the most frequent (28/36; 77.8%), presenting spa types t011, t034, t2576, t4132, t588 and t899. Other livestock-associated MRSA STs (ST9-t899, ST5-t002, ST692-t8646 or the newly described ST4034-t899) were also sporadically identified. In seven isolates (19.4%), one or more staphylococcal enterotoxin genes were detected, with sea, seg and sei prevailing. Three isolates from turkey [ST398-t899 (n = 2) and ST398-t011] harboured the sak gene, and the latter also harboured the sea gene. Seven isolates from poultry harboured the φSa3 prophage and were resistant to tetracycline.

Conclusion: Specific kinds of meat appear to be a possible source of MRSA, although the risk to humans is hard to define. Therefore, surveillance of MRSA in meat as well as hygienic practices should be improved.

Keywords: Enterotoxin genes; MLST; MRSA; Virulence genes; spa typing.