title: Antimicrobial susceptibility of Staphylococcus aureus from retail ground meats.
abstract: The aim of this study was to characterize antimicrobial resistance in Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), recovered from raw retail meat products purchased in the Washington, D.C., area. From March to August 2008, 694 samples of ground  beef (n = 198), ground pork (n = 300), and ground turkey (n = 196) were collected by random sampling from stores of three grocery chains. In total, 200 S. aureus isolates (29%) were recovered by direct plating. When tested for susceptibility to 22 antimicrobials,  69% of the S. aureus isolates were resistant to tetracycline, 26% to penicillin, 17% to ampicillin, 13% to methicillin, 8% to erythromycin, 4.5% to clindamycin, 1.5% to gentamicin, and 0.5% to chloramphenicol, oxacillin, cefoxitin, or quinupristin-dalfopristin. However, 27% of the isolates  were susceptible to all tested antimicrobials. More turkey and pork isolates were resistant to ampicillin, penicillin, and tetracycline than were beef isolates (P < 0.05). Additionally, 17% of the turkey and 17% of the pork isolates were resistant to methicillin (MIC ≥ 16 μg/ml),  whereas no beef isolates were resistant to the antimicrobial agent. A single MRSA (methicillin MIC > 32 μg/ml) isolate containing the mecA gene with additional resistance to erythromycin, clindamycin, oxacillin plus 2% NaCl, cefoxitin, ampicillin, penicillin, quinupristin-dalfopristin,  tetracycline, and gentamicin was recovered from one pork sample. The presence of antimicrobial-resistant S. aureus, coupled with the relative lack of such studies in the United States, suggests that further investigations on MRSA in the food supply are needed despite the low rate of  MRSA found in this particular study.
authors: Gemstone Program at the University of Maryland, University of Maryland, College Park, Maryland 20742, USA.
authors: Alina
authors: A
authors: Kelman
authors: Yee-Ann
authors: YA
authors: Soong
authors: Nicole
authors: N
authors: Dupuy
authors: Daniel
authors: D
authors: Shafer
authors: William
authors: W
authors: Richbourg
authors: Kourtney
authors: K
authors: Johnson
authors: Twain
authors: T
authors: Brown
authors: Edward
authors: E
authors: Kestler
authors: Yi
authors: Y
authors: Li
authors: Jie
authors: J
authors: Zheng
authors: Patrick
authors: P
authors: McDermott
authors: Jianghong
authors: J
authors: Meng
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D008461:Meat Products / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013552:Swine; D014422:Turkeys