title: Methicillin-resistant Staphylococcus aureus of lineage ST398 as cause of mastitis in cows.
abstract: The objective of this study was to analyse the prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) in milk of cows with mastitis. The California mastitis test (CMT) was used to detect the presence of mastitis in all 100 cows of a farm in Brazil. The CMT was positive in milk of 115 mammary quarters from 36 cows (36%). MRSA isolates were recovered from 4 of these 36 cows with mastitis (11%), and they were further characterized (one MRSA/sample). The four MRSA isolates were typed as t011-ST398-agr1-SCCmecV and presented two different pulsed-field-gel-electrophoresis-ApaI patterns. These four MRSA isolates showed resistance to tetracycline, streptomycin and ciprofloxacin, carried the mecA, blaZ, tet(K), and tet(M) resistance genes, and presented the S84L and S80F amino acid substitutions in GyrA and GrlA proteins, respectively. Two ST398 isolates exhibited resistance to gentamicin and tobramycin [with aac(6)-aph(2") and ant(4)-Ia genes] and one isolate resistance to clindamycin [with lnu(B) and lsa(E) genes]; this latter isolate also carried the spectinomycin/streptomycin resistance genes spw and aadE. MRSA of lineage ST398 is worldwide spread, normally multidrug resistant and may be responsible for bovine mastitis. To our knowledge, this is the first detection of MRSA-ST398 in Brazil.
  
  
  CONCLUSIONS
  Few studies on the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from bovine isolates have been performed in Brazil. MRSA of lineage ST398 is worldwide spread and associated with farm animals. Multidrug-resistant MRSA-ST398 isolates were recovered in 11% of mastitic cows from a single farm, with one isolate carrying the unusual lsa(E), spw and aadE genes. To our knowledge, this is the first detection of MRSA-ST398 isolates in milk samples of cows with mastitis in Brazil.
authors.affiliation: Department of Microbiology and Immunology, UNESP, Botucatu, SP, Brazil; Department of Agri-food Industry, Food and Nutrition - LAN, USP, Piracicaba, SP, Brazil.
authors.forename: N C C
authors.initials: NC
authors.lastname: Silva
authors.forename: F F
authors.initials: FF
authors.lastname: Guimarães
authors.forename: M P
authors.initials: MP
authors.lastname: Manzi
authors.forename: A Fernandes
authors.initials: AF
authors.lastname: Júnior
authors.forename: E
authors.initials: E
authors.lastname: Gómez-Sanz
authors.forename: P
authors.initials: P
authors.lastname: Gómez
authors.forename: H
authors.initials: H
authors.lastname: Langoni
authors.forename: V L M
authors.initials: VL
authors.lastname: Rall
authors.forename: C
authors.initials: C
authors.lastname: Torres
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D002417:Cattle; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005798:Genes, Bacterial; D008414:Mastitis, Bovine / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology*; D058889:Molecular Typing; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents
keywords: ST398; Staph. aureus; bovine; mecA; methicillin-resistant Staphylococcus aureus; t011