title: Antimicrobial susceptibility and invasive ability of Staphylococcus aureus isolates from mastitis from dairy backyard systems.
abstract: Fifteen (15) backyard farms were investigated to determine the antimicrobial susceptibility and invasion ability of S. aureus isolates from cows with subclinical mastitis in México. A total of 106 cows were sampled and 31 S. aureus isolates were recovered. S. aureus isolates were resistant to penicillin class antibiotics and susceptible to gentamicin and cetyltrimethylammonium bromide. STA9 and STA13 isolates were resistant to erythromycin (MIC > 25 microg/ml) and lincomycin (STA13, MIC > 25 microg/ml; STA9, MIC > 100 microg/ml). STA9 isolate harbors the erm(B) and msr(A) genes, whereas STA13 isolate harbors the erm(C) gene. STA9 and STA13 isolates contains the lnu(A) gene. Only 5 isolates (STA11, STA13, STA14, STA15 and STA21) were able to internalize in bovine mammary epithelial cells. These results indicate that S. aureus isolates from dairy backyard farms showed differences in the antimicrobial susceptibility patterns and invasion ability in bovine mammary epithelial cells. This kind of evaluations should be performed in different dairy regions, since resistance patterns and isolate diversity vary on a per-region basis.
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología-Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Apdo. Postal 53, Administración Chapultepec, C.P. 58262 Morelia, Michoacán, México.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Ochoa-Zarzosa
authors.forename: Pedro D
authors.initials: PD
authors.lastname: Loeza-Lara
authors.forename: Francisco
authors.initials: F
authors.lastname: Torres-Rodríguez
authors.forename: Heber
authors.initials: H
authors.lastname: Loeza-Angeles
authors.forename: Nidia
authors.initials: N
authors.lastname: Mascot-Chiquito
authors.forename: Sonia
authors.initials: S
authors.lastname: Sánchez-Baca
authors.forename: Joel E
authors.initials: JE
authors.lastname: López-Meza
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003612:Dairying; D024881:Drug Resistance, Bacterial; D004847:Epithelial Cells / Q000382:microbiology / Q000648:ultrastructure; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology / Q000648:ultrastructure; D008414:Mastitis, Bovine / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology*; D010406:Penicillins / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D010406:Penicillins