Mariela E. Srednik
University of Buenos Aires, Argentina
Title: Bovine mastitis: staphylococci and resistance genes towards β-lactams and macrolides-lincosamides antibiotics in Argentina
Biography
Biography: Mariela E. Srednik
Abstract
Bovine mastitis causes important economic losses in the dairy industry. Staphylococcus aureus and coagulase-negative staphylococci (CNS) are commonly isolated from bovine mastitis. β-lactams and macrolides-lincosamides (ML) antibiotics are frequently used in intrammamary therapy. CNS can be considered reservoir of antimicrobial resistance genes. The gene blaZ confer resistance to some β-lactam antimicrobials whereas the mecA and mecC genes confer resistance to all β-lactams. The genes ermA, ermB, ermC, mefA, msrA, mphC and lnuA confer resistance to ML antimicrobials. S. aureus resistance to β-lactams in Argentina is 23.1%. Among 80 S. aureus isolates, 32 (40%) were positive to blaZ gene and 15 (18.75%) were carriers of ML resistant genes: ermB and mefA (n=4), ermB (n=2) mefA (n=3), ermB, ermC and mefA (n=1), ermA, ermB, ermC and mefA (n=1), ermB, mefA, lnuA and msrA (n=1), ermC, ermB and lnuA (n=1), ermA (n=1) and lnuA (n=1). Among 90 CNS isolates, 12 (13.3%), 4 (4.4%), and 1 (1.1%) were positive for blaZ, mecA and mecC genes, respectively. Both blaZ and mecA genes were only found in one isolate whereas 6 (6.7%) isolates were resistant to ML antimicrobials via the following genes: ermC (n=1), ermB and ermC (n=2), ermB, ermC and mphC (n=1), mphC (n=1), and mphC and mrsA (n=1). The recently described mecC gene has been detected by PCR in a few CNS of animal origin only around Europe. We describe here for the first time a mecC positive isolate of CNS from bovine mastitis in Argentina. Identification of mastitis pathogens is important for selecting appropriate antimicrobial therapy. Reservoirs of antimicrobial resistance genes are potential threat to public health