Species identification and antimicrobial susceptibility profile of bacteria causing subclinical mastitis in buffalo

Abstract

ABSTRACT: Microorganisms causing subclinical mastitis in water buffalo were isolated from 20 buffalo milk samples at four dairy farms located in central region of São Paulo State, Brazil, through testing of somatic cell count (SCC), standard plate count (SPC), biochemical, PCR assays and antimicrobial profile. The SCC showed average of 721,000 cells/mL in the milk, indicating the presence of subclinical mastitis. The overall average for SPC was 1.8 x 104 CFU/mL. The microorganism most frequently isolation according to biochemical tests were: Staphylococcus epidermidis (17%), Staphylococcus aureus (15%), Bacillus spp. (14%), Acinetobacter spp. (12.5%); with intermediate frequency: Pseudomonas aeruginosa (9.5%); Shigella flexneri (7.0%), Streptococcus spp. (5.5%), Corynebacterium spp. (5.0%), Escherichia coli (4.5%), Serratia marcescens (4.0%), Stenotrophomonas maltophilia (4.0%), and low incidence: Klebsiella rhinoscleromatis (0.5%), Klebsiella ozaenae (0.5%), Tatumella ptyseos (0.5%), Enterobacter cloacae (0.5%). The molecular analysis indicated that samples positive by culture method of the genera Staphylococcus, Streptococcus and E. coli were positive by PCR. Para S. aureus and S. epidermidis the highest percentages of observed sensitivity were gentamicin (100%) and vancomycin (100%); for the genus Streptococcus to gentamicin and oxacillin and E. coli to Ampicilin. These findings may help in the control and treatment of subclinical mastitis in buffaloes and contribute to improving the efficiency and quality of the milk produced.