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|Title:||Contamination of retail samples of roasted pork (Sui Mei) in Hong Kong|
|Source:||22nd European Congress of Clinical Microbiology & Infectious Diseases, London, England, 31 Mar-3 Apr, 2012 How to cite?|
|Abstract:||Objectives: Staphylococcus aureus is a major cause of food poisoning and in Hong Kong the majority of such outbreaks have been ascribed to intake of roasted pork although there appear to have been no studies to determine rates of contamination of this popular local food. This study aimed to determine rates of S. aureus contamination. The presence of enterotoxin and leukocidin genes and resistance to methicillin was determined.|
Methods: Samples were purchased from 50 retail outlets preparing roasted pork on the premises. 5ml of a 25g homogenate were enriched in 6% NaCl Trytone Soy Broth (TSB) for 24h and then streaked onto ChromeID SA agar. 5 ml of the TSB were further enriched in TSB with 5mg/L ceftizoxime and 75mg/L aztreonam for 24h before plating onto ChromeID MRSA agar. S. aureus isolates were confirmed by latex agglutination and susceptibility to cefoxitin determined by disc diffusion. Isolates appearing resistant were confirmed as methicillin-resistant S. aureus (MRSA) by presence of mecA and SCCmec type was determined. All isolates were characterized for presence of enterotoxins SEA-SEE and Panton-Valentin Leukocidin (PVL).
Results: 24 (48%) samples yielded S. aureus, two samples having two strains. Of these three were resistant to cefoxitin, but only two (4%) were mecA positive (one SCCmec IVb, one V). The remaining strain was shown to be a beta-lactamase hyper producer (MIC peniciliin 10g/L). Enterotoxin genes were present in five methicillin-sensitive isolates and PVL in one.
Conclusions: Almost half of the samples were positive for S. aureus and 10% of samples yielded enterotoxin-positive strains, confirming that this food could be an important vehicle for staphylococcal food poisoning since is it usually kept at room temperature before sale and not reheated before consumption. The presence of community associated MRSA in two samples may be of concern as it demonstrates its ability to be transferred by contaminated foodstuffs. High rates of MRSA have been reported in pork carcasses in Hong Kong and further study of the source of contamination on roasted meat are needed.
|Appears in Collections:||Conference Paper|
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