title: Molecular identification of coagulase-negative staphylococci isolated from bovine mastitis and detection of β-lactam resistance.
abstract: BACKGROUND
  Bovine mastitis is a frequent cause of economic loss in dairy herds. Coagulase-negative staphylococci (CoNS) are increasing in importance as causeof bovine intramammary infection (IMI) throughout the world in recent years. CoNShave been isolated from milk samples collected from cows with clinical andsubclinical mastitis in several countries. Identification of mastitis pathogensis important when selection appropriate antimicrobial therapy.
  
  
  METHODS
  A total of 93 strains of Staphylococcusspp isolated from bovine clinical andsubclinical mastitis in Argentina during 2010-2013 were identified by Restriction Fragment Length Polymorphism (RFLP)-PCR using the gap gene. The isolates were tested by PCR for the presence of blaZ gene and mecA gene and were tested by disk diffusion for the susceptibilityto penicillin and cefoxitin.
  
  
  RESULTS
  The most common CoNS species was S.chromogenes 46.2% (43/93), followed by S. devriesei 11.8% (11/93) and S. haemolyticus 9.7% (9/93). The blaZ gene was detected in 19 (20.4%) but only 16 (17.2%) isolates were resistant to penicillin; the mecA was detected in6 (6.5%) isolates but only 4 (4.3) were resistant to cefoxitin. The 6 mecA-positive isolates showed oxaxillinMICs ≤ 0.5 μg/ml.
  
  
  CONCLUSIONS
  CoNSare important minor mastitis pathogens and can be the cause of substantial economic losses. Despite the low resistance to PEN in Argentina, the presenceof MR isolates found in this study emphasize the importance of identificationof CoNS when an IMI is present because of the potentially risk of lateraltransfer of resistance genes between staphylococcal species.
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina. maru_sred@fvet.uba.ar.
authors.forename: Mariela Elizabeth
authors.initials: ME
authors.lastname: Srednik
authors.forename: Mario Andres
authors.initials: MA
authors.lastname: Grieben
authors.forename: Adriana
authors.initials: A
authors.lastname: Bentancor
authors.forename: Elida Raquel
authors.initials: ER
authors.lastname: Gentilini
mesh_terms: D000818:Animals; D001118:Argentina; D002417:Cattle; D003030:Coagulase / Q000172:deficiency*; D005260:Female; D005798:Genes, Bacterial; D008414:Mastitis, Bovine / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013210:Staphylococcus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D018440:beta-Lactam Resistance
chemical_list: D003030:Coagulase