High prevalence and molecular characterization of methicillin-resistant Staphylococcus aureus isolated from retailed meats, south Thailand

Methicillin-resistant Staphylococcus aureus is an important pathogenic bacterium playing crucial roles in healthcare institutions including the communities. Moreover, food-borne illnesses caused by MRSA were also reported. In this study, 50 meat samples were investigated for the presence of MRSA. Suspected S. aureus colonies were selected and confirmed as S. aureus by 16S rRNA gene amplification using S. aureus specific primers. Investigation of mecA and other virulence genes, were carried out by PCR approach. Of 474 suspected isolates, 185 (39.02%) were confirmed to be mecA^+ S. aureus. All mecA^+ S. aureus were isolated from 34 meat samples (68%). Of these 185 isolates, 103, 42 and 40, were obtained from beef, pork and chicken, respectively. Two (1.08%) mecA^+ S. aureus from beef, PSU123 and PSU124, and two (1.08%) from chicken, PSU125 and PSU126, posessed von Willebrand factor binding protein gene. One (0.54%) of mecA^+ S. aureus obtained from chicken, PSU127, revealed the posession of spa gene. MRSA typing by SCCmec type revealed that PSU127 belonged to type IV while PSU123 to PSU126, were thought to be classified as SCCmec type other than type I to VI. Pulsed-field gel electrophoresis exhibited the distantly relationship among five mecA^+ S. aureus strains. The majority of pathogenic strains exhibited the resistance to penicillin G, erythromycin, ceftazidime, clindamycin and fusidic acid while PSU125 revealed the resistance to extra antimicrobial agent, tetracycline. This is the first report of MRSA contamination in retailed meats sold in south of Thailand.