AVN WEB Desk
BANGKOK, Thailand: A recent research conducted in Sakon Nakhon, Thailand, has revealed evidence of antimicrobial-resistant bacteria responsible for bovine mastitis — an inflammation of the mammary gland in dairy cattle, causes significant economic losses due to reduced milk quantity and quality—however, the majority of pathogens remain susceptible to most antimicrobials.
The findings, published in the journal Veterinary World, explore the impact of extensive or incorrect use of antibiotics in veterinary practices.
During the study, researchers screened animals from 35 dairy farms for clinical and subclinical mastitis using the California Mastitis Test and clinical examinations. Bacterial species and antimicrobial resistance genes were identified using polymerase chain reaction, while disk diffusion and broth microdilution tests assessed antimicrobial susceptibility.
The study identified a high prevalence of Staphylococcus epidermidis-induced mastitis (38.10pc), followed by Streptococcus agalactiae (33.33pc), Streptococcus uberis (25pc), Klebsiella pneumoniae (8.33pc), and Staphylococcus aureus (4.76pc).
Notably, Staphylococcus spp. isolates showed 100pc susceptibility to cefoxitin, with no antibiotic-resistant genes detected.
Resistance profiles for Streptococcus spp. indicated a predominant presence of the tetM gene (55.63pc), followed by tells and erm(B) (16.90pc). Resistance to tetracycline was particularly high (85.92pc), with lower resistance observed for clindamycin (29.58pc), erythromycin (15.49pc), levofloxacin (14.08pc), and penicillin (0pc).
Gram-negative isolates, including K. pneumoniae (8.33pc), Klebsiella variicola (2.38pc), Klebsiella quasipneumoniae (1.19pc), and Escherichia coli (1.19pc), were still largely susceptible to meropenem (100pc), ceftazidime (97.06pc), ceftriaxone (79.41pc), and ciprofloxacin (79.41pc).
The researchers concluded that mastitis pathogens in the region remain mostly susceptible to antimicrobials, with the exception of Streptococcus spp. against tetracycline. They recommend broader studies involving more dairy farms to gain comprehensive insights.
