Multidrug Resistance and Molecular Characterization of Streptococcus agalactiae Isolates From Dairy Cattle With Mastitis

HERNANDEZ, LUCIANA; BOTTINI, ENRIQUETA; CADONA, JIMENA; CACCIATO, CLAUDIO; MONTEAVARO, CRISTINA; BUSTAMANTE, ANA; SANSO, ANDREA MARIEL

Frontiers in Cellular and Infection Microbiology

Frontiers media

Lugar: Lausana; Año: 2021 vol. 11

Streptococcus agalactiae is a pathogen-associated to bovine mastitis, a health disorderresponsible for significant economic losses in the dairy industry. Antimicrobial therapyremains the main strategy for the control of this bacterium in dairy herds and human Inorder to get insight on molecular characteristics of S. agalactiae strains circulating amongArgentinean cattle with mastitis, we received 1500 samples from 56 dairy farms between2016 and 2019. We recovered 56 S. agalactiae isolates and characterized them in relationto serotypes, virulence genes, and antimicrobial susceptibility. Serotypes III and II were themost prevalent ones (46% and 41%, respectively), followed by Ia (7%). In relation to the 13virulence genes screened in this study, the genes spb1, hylB, cylE, and PI-2b werepresent in all the isolates, meanwhile, bca, cpsA, and rib were detected in differentfrequencies, 36%, 96%, and 59%, respectively. On the other hand, bac, hvgA, lmb, PI-1,PI-2a, and scpB genes could not be detected in any of the isolates. Disk diffusion methodagainst a panel of eight antimicrobial agents showed an important number of strainsresistant simultaneously to five antibiotics. We also detected several resistance-encodinggenes, tet(M), tet(O), ermB, aphA3, and lnu(B) (9%, 50%, 32%, 32%, and 5%,respectively). The results here presented are the first molecular data on S. agalactiaeisolates causing bovine mastitis in Argentina and provide a foundation for the developmentof diagnostic, prophylactic, and therapeutic methods, including the perspective ofa vaccine