Virulence-associated genes and molecular typing of Streptococcus uberis associated with bovine mastitis in northern Thailand

Abstract

Streptococcus uberisis a major bovine mastitis pathogen. Several studies have revealed a persistence of specific strains ofS. uberiswith enhanced virulence or transmissibility. We aimed to investigate the presence ofS. uberisvirulence-associated genesincluding plasminogen activator ( pauA ), glyceraldehyde-3-phosphate dehydrogenase ( gapC ), oligopeptide permease ( oppF ), metaltransporter uberis A ( mtuA ), hyaluronic acid capsules ( hasA ,hasB ,hasC ), lactoferrin binding protein ( lbp ), adhesion protein ( sua ),and CAMP factor ( cfu ) as well as the genetic profiles using pulsed-field gel electrophoresis (PFGE) among isolates from cases of clinicalmastitis, subclinical mastitis, and intramammary infection with low somatic cell count in dairy cows. A total of 642 milk samples from178 milking cows of 53 farms in Chiang Mai, Thailand, were collected and cultured. Eighty-eightS. uberisisolates were identified. Themost common pattern of virulence-associated genes washasA+hasB+hasC+sua+gapC+lbp+pauA+oppF+mtuA(34.1%, 30/88). PFGEwas performed with 71 isolates, which could be classified into 56 pulsotypes.S. uberisisolates tended to be clustered by farms regardlessof the severity of infection. Therefore, molecular epidemiological investigation can be useful in developing an effective control strategyfor bovine mastitis caused byS. uberisin dairy farms.