title: Characterization of coagulase-negative staphylococcus species from cows' milk and environment based on bap, icaA, and mecA genes and phenotypic susceptibility to antimicrobials and teat dips.
abstract: The aim of this study was to investigate whether the main coagulase-negative staphylococci (CNS) species involved in bovine intramammary infections (IMI) possess specific characteristics that promote colonization of the udder. Virulence markers associated with biofilm formation, antimicrobial resistance, and biocide tolerance were compared between typically contagious CNS species (Staphylococcus chromogenes, Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus simulans) and those rarely causing IMI (Staphylococcus sciuri, Staphylococcus equorum, and others) to find possible associations with pathogenicity. Coagulase-negative staphylococci isolates (n=366) belonging to 22 different species were analyzed by PCR for the presence of the biofilm-associated genes bap and icaA, and the methicillin resistance gene mecA. A selection of 82 isolates was additionally tested for their susceptibility to 5 antibiotics and 2 commercial teat dip products. Minimum inhibitory concentrations of antimicrobials were determined by Etest (AB bioMérieux, Marcy l'Etoile, France), and a microdilution method was optimized to determine minimum biocidal concentrations of teat dips. The bap, icaA, and mecA genes were detected significantly more in isolates from CNS species typically living in the cows' environment than in isolates from IMI-causing species. Antimicrobial resistance was mainly against erythromycin (23%) or oxacillin (16%), and was detected more often in the environmental species. The isolates least susceptible to the teat dips belonged to the IMI-causing species Staph. chromogenes and Staph. simulans. We concluded that carriage of biofilm genes and antimicrobial resistance were not associated with the ability to colonize the mammary gland because free-living CNS species constituted a more significant reservoir of biofilm and resistance determinants than did IMI-causing species. In contrast, increased tolerance to biocides may favor the establishment of bovine IMI by some CNS species.
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, 9090 Melle, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Piessens
authors.forename: S
authors.initials: S
authors.lastname: De Vliegher
authors.forename: B
authors.initials: B
authors.lastname: Verbist
authors.forename: G
authors.initials: G
authors.lastname: Braem
authors.forename: A
authors.initials: A
authors.lastname: Van Nuffel
authors.forename: L
authors.initials: L
authors.lastname: De Vuyst
authors.forename: M
authors.initials: M
authors.lastname: Heyndrickx
authors.forename: E
authors.initials: E
authors.lastname: Van Coillie
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002417:Cattle; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics* / Q000502:physiology; D008321:Mammary Glands, Animal / Q000382:microbiology; D008414:Mastitis, Bovine / Q000188:drug therapy / Q000382:microbiology*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008892:Milk / Q000382:microbiology*; D010641:Phenotype; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity; D041162:Staphylococcus haemolyticus / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins