1Department of Animal Science, Xizang Agriculture and Animal Husbandry University, Key Laboratory for Prevention and Control of Hydatid Disease in Tibet (Co-constructed by Ministry and Province), Linzhi, Tibet 860000, China
2Lhasa Pratacultural Research Institute, Lhasa, Tibet 850000, China
*Corresponding author’s email: xzslsz@163.com
Received: 17 June 2024 / Accepted: 26 November 2024 / Published Online: 29 January 2025
Abstract
This study aimed to investigate the antibiotic sensitivity and resistance profiles of Streptococcus isolated from diarrhea in yaks in Tibetan regions. We successfully isolated and identified Streptococcus from fecal samples using morphological analysis and PCR amplification. Subsequent bacterial susceptibility tests and resistance gene detection revealed that the overall isolate rate of Streptococcus from yaks in Tibet was 57.68%, with Changdu recording the highest (71.43%) and Naqu the lowest (34.09%). The bacteria exhibited significant resistance to macrolides, particularly Erythromycin (52.86%) and Midecamycin (52.14%), β-Lactam resistance, including Ceftazidime, Cephazolin, and Carbenicillin, was the lowest at 7.14%, 2.15%, and 7.14%, respectively. Among the 140 isolates, 37 distinct resistance patterns were identified, with ERY/MID being the most prevalent for Macrolides. The detection rates for the resistance genes were as follows: erma (38.36%), ermb (65.20%), mefa (28.93%) for Macrolides; tetk (13.42%), tetl (14.47%), teto (11.53%), and tetm (20.34%) for Tetracyclines; and pbp2b (5.24%) for β-lactams. The conformity between resistance phenotypes and genes was high, with 82.83% for Tetracyclines, 89.14% for Macrolides, and 95.80% for β-lactams. These findings indicate that Streptococcus in yaks exhibits a predominant resistance to macrolides, accompanied by multiple resistance patterns, with the ERY/MID pattern dominant.
Keywords: Yaks, Streptococcus, Isolation and identification, Susceptibility test, Resistance analysis
