Characterization of borderline oxacillin-resistant Staphylococcus aureus isolated from food of animal origin.
In this study, the molecular characteristics of food-derived oxacillin-resistant Staphylococcus aureus were determined. Eight borderline oxacillin-resistant strains with MICs of 2 to 4 microg/ml were identified from 132 S. aureus isolates of food origin. One of the two isolates with a MIC of 4 microg/ml was methicillin-resistant determinant (mecA) gene positive, and the other six with MICs of 2 microg/ml were mecA negative. The mecA-positive isolate was classified as sequence type (ST)228, staphylococcal protein A (spa) type t041, and carried the staphylococcal cassette chromosome mec type I element. Two borderline oxacillin-resistant strains were classified as spa t008 and ST8, and the remaining five as spa t164 and ST20. The mecA-positive strain and four borderline oxacillin-resistant strains were found enterotoxigenic. The enterotoxin genes detected in these strains included selp, egc1, and sed-sej-selr. The borderline-resistant S. aureus isolates from a manually handled product, i.e., minced pork, were shown genetically related to strains associated with human infections. This suggests that humans can be considered as a source of contamination of this food with oxacillin-resistant S. aureus strains. The genotypes of the investigated milk borderline-resistant isolates were shown to occur not only in cows, but also in humans. Since manual handling is reduced in raw milk production, a human origin of S. aureus seems unlikely. Because knowledge of the genotypes of animal staphylococci is limited, more research is needed to address the question of the origin of antibiotic-resistant S. aureus strains in food.
Bystroń
Jarosław
J
Department of Food Hygiene and Consumer Health Protection, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
Podkowik
Magdalena
M
Korzekwa
Kamila
K
Lis
Elzbieta
E
Molenda
Jerzy
J
Bania
Jacek
J
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D005506:Food Contamination / Q000032:analysis*; D005838:Genotype; D006801:Humans; D008461:Meat Products / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology; D010068:Oxacillin / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D010068:Oxacillin