Otpornost na antibiotike i geni za virulenciju sojeva vrste Streptococcus agalactiae izdvojenih iz krava kod supkliničke upale mliječne žlijezde.

Twenty-seven S. agalactiae isolates obtained after screening 89 cows for subclinical mastitis were studied for antibiotic resistance and virulence genes. The highest resistance was found by Disc diffusion method for Streptomycin (85.1%) whereas the lowest resistance was found for Gentamicin (3.7%). Resistance against Tetracycline, Erythromycin, Co-trimoxazole, Ampicillin and Enrofloxacin was 55.5%, 33.3%, 11.1%, 11.1%, and 7.4% respectively. PCR based detection revealed three isolates carrying the tetO gene associated with Tetracycline resistance and seven isolates carrying the ErmB gene associated with Erythromycin resistance. Molecular detection of virulence associated genes revealed that out of 27 isolates of S. agalactiae, none was carrying the bca gene, while 6, 7, 8 and 6 isolates were positive for ScpB, rib, lmb and cylE genes respectively.Ukupno je 27 izolata vrste S. agalactiae bilo izdvojeno iz 89 krava sa supkliničkom upalom mliječne žlijezde te pretraženo na otpornost na antibiotike i gene za virulenciju. Difuzijskim postupkom ustanovljeno je da su izolati najčešće bili otporni na streptomicin (85,1%), a najrjeđe na gentamicin (3,7%). Otpornost na tetraciklin dokazana je u 55,5% izolata, na eritromicin u 33,3%, na kotrimoksazol u 11,1%, na ampicilin u 11,1% te na enrofloksacin u 7,4% izolata. Lančanom reakcijom polimerazom u tri je izolata dokazan gen tetO povezan s otpornošću na tetraciklin, a u sedam gen ErmB povezan s otpornošću na eritromicin. Molekularnim dokazivanjem gena odgovornih za virulenciju ni u jednog od 27 pretraženih izolata vrste S. agalactiae nije bio dokazan gen bca, dok je u šest izolata bio dokazan gen ScpB, u sedam gen rib, u osam gen lmb te u šest izolata gen cylE