Antibiogram Patterns of Mastitis-Associated Bacteria Identified from California Mastitis Positive Milk Samples

Aim: To find the antibiogram of the identified bacterial isolates obtained from CMT positive milk samples Study Design: The identified bacterial isolates obtained from California mastitis test positive milk samples of in and around Bengaluru district, Karnataka were subjected to antimicrobial susceptibility test. Place and Duration of Study: The work was carried out in the Department of Dairy Microbiology, Dairy Science College, KVAFSU, Hebbal, Bengaluru, Karnataka for period of one year. Methodology: The identified mastitic causing bacterial isolates obtained were subcultured and through disc assay method, antimicrobial sensitivity test was conducted for 18 antibiotic discs to declare the isolates as susceptible or resistant. Result: In the present study, a total of 45 identified bacterial isolates obtained from CMT positive comprised of 22 Streptococcus spp. followed by 18 Staphylococcusspp and 5 of Gram negative bacteria. All the species of Streptococcus and Staphylococcous showed 100% resistance to both pefloxacin & pencillin as well around 80% to bacitracin. Gram negative isolates showed 100% resistance to penicillin and streptomycin. Conclusion: Species of Streptococcus as well as Staphylococcusexhibited susceptibility to levofloxacin and tobramycin by around 50% whereas Gram negative isolates were sensitive to ofloxacin by 100%, while 80% to levofloxacin. Both Gram positive and Gram negative isolates were resistant to many antibiotics depicting development of multidrug resistance mechanism in the pathogens. It was interesting to observe that levofloxacin belonging to fluoroquinolone class, a broad spectrum antibiotic that stops DNA replication of bacterial pathogens can be used for treating mastitis as per the present study