title: Isolation of methicillin-resistant Staphylococcus aureus (MRSA) from retail meats in Hong Kong.
abstract: OBJECTIVE
  The presence of methicillin-resistant Staphylococcus aureus (MRSA) on meat purchased from retail outlets may allow its spread to households and represents a risk for colonization and possibly infection of consumers. Improved isolation methods have indicated that more than 10% of samples are positive. We aimed to determine rates of MRSA contamination of meat samples, including comparison of fresh and frozen samples. We characterized isolates and determined their antibiotic susceptibility.
  
  
  METHODS
  Samples of raw meats commonly consumed in Hong Kong were investigated for MRSA contamination using a double-enrichment isolation method. Isolates were characterized by antibiotic susceptibility testing, presence of mecA, SCCmec type, staphylococcal enterotoxins, Panton-Valentin leukocidin (PVL), and spa type. Differences in rates of MRSA contamination between meat types, rearing method, locations, sources, and fresh or frozen storage were compared.
  
  
  RESULTS
  MRSA was recovered from 21.9% of pork samples (78/355), 6.8% chicken (31/455), and 4.4% of beef (17/380). Isolation was considerably higher from fresh pork (47%) than frozen (0.6%), whereas contamination rates in fresh (6%) and frozen (7%) chicken were similar. All strains were multidrug resistant. All contaminated fresh pork and most frozen chicken originated from China. Most isolates belonged to CC9, being SCCmec IVb and spa type t899 or closely related spa types, but one chicken sample yielded ST398. Five strains carried spa types associated with human isolates. The egc enterotoxin group was present in the majority of isolates, but PVL in only three from chicken.
  
  
  CONCLUSIONS
  The predominance of t899 in isolates indicates that the primary source of contamination may be pig carcasses, previously demonstrated to frequently harbor CC9-positive MRSA in Hong Kong and China. The high rates of meat contamination suggest that improvements in food safety and personal hygiene guidelines may be advisable to reduce risk of spread of these MRSA strains in the community.
authors.affiliation: Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. htmboost@polyu.edu.hk
authors.forename: Maureen V
authors.initials: MV
authors.lastname: Boost
authors.forename: Anthony
authors.initials: A
authors.lastname: Wong
authors.forename: Jeffery
authors.initials: J
authors.lastname: Ho
authors.forename: Margaret
authors.initials: M
authors.lastname: O'Donoghue
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics / Q000302:isolation & purification; D002417:Cattle; D002645:Chickens; D002681:China; D024901:Drug Resistance, Multiple, Bacterial; D004768:Enterotoxins / Q000235:genetics / Q000302:isolation & purification; D005098:Exotoxins / Q000235:genetics / Q000302:isolation & purification; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D061353:Food Storage; D006723:Hong Kong; D007956:Leukocidins / Q000235:genetics / Q000302:isolation & purification; D008460:Meat / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004768:Enterotoxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin