Abdelfattah Essam M, Ekong Pius S, Okello Emmanuel, Chamchoy Tapakorn, Karle Betsy M, Black Randi A, ElAshmawy Wagdy, Sheedy David, Williams Deniece R, Lehenbauer Terry W, Byrne Barbara A, Aly Sharif S
Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California, Davis, Tulare, CA, United States.
Department of Animal Hygiene and Veterinary Management, Faculty of Veterinary Medicine, Benha University, Al Qalyubiyah, Egypt.
Front Vet Sci. 2025 Feb 10;11:1504640. doi: 10.3389/fvets.2024.1504640. eCollection 2024.
The current study objective was to investigate the risk factors associated with the isolation of antimicrobial-resistant , spp., and spp. (ES) from the feces of dairy cows in California (CA). A longitudinal study was conducted on ten dairies, and a random sample of cattle (late pregnant heifers and dry cows) stratified by each herd's parity distribution were followed monthly from close-up to 120 days in milk during fall to winter 2018 (winter season) and spring to summer 2019 (summer season). Gastrointestinal commensals were isolated from fecal samples and tested for antimicrobial susceptibility using the broth microdilution method against a selected panel of antimicrobial drugs (AMD). Eight dairies used blanket AMD therapy at dry-off for all lactating cows, while the remaining two dairies did not use any AMD treatment at dry-off. Clinical mastitis was identified as the most common indication for AMD use across the study dairies. Intramuscular administration of ceftiofur hydrochloride to treat lameness and unknown disease during lactation was significantly associated with the isolation of tetracycline-resistant fecal . Resistance to ceftiofur, tetracycline, or trimethoprim-sulfamethoxazole in fecal was significantly higher in the winter than in the summer season. In contrast, resistance to tetracycline, florfenicol, tilmicosin, tildipirosin, or tiamulin in fecal gram-positive commensals was significantly higher in the summer than in the winter. In conclusion, AMD usage practices and seasonal variations significantly influenced the AMR of and ES in the feces of dairy cattle.
本研究的目的是调查与从加利福尼亚州（CA）奶牛粪便中分离出耐抗菌药物的 、 菌属和 菌属（ES）相关的风险因素。对10个奶牛场进行了一项纵向研究，在2018年秋季至冬季（冬季）和2019年春季至夏季（夏季）期间，从围产期到产奶120天，每月对按各牛群胎次分布分层的牛（怀孕后期小母牛和干奶牛）随机抽样。从粪便样本中分离出胃肠道共生菌，并使用肉汤微量稀释法针对选定的一组抗菌药物（AMD）测试其抗菌药敏性。8个奶牛场在干奶期对所有泌乳奶牛采用全面AMD治疗，而其余两个奶牛场在干奶期未使用任何AMD治疗。临床乳腺炎被确定为整个研究奶牛场使用AMD的最常见指征。在泌乳期肌肉注射盐酸头孢噻呋治疗跛行和不明疾病与耐四环素粪便 的分离显著相关。粪便 中对头孢噻呋、四环素或甲氧苄啶-磺胺甲恶唑的耐药性在冬季显著高于夏季。相比之下，粪便革兰氏阳性共生菌对四环素、氟苯尼考、替米考星、替地米星或泰妙菌素的耐药性在夏季显著高于冬季。总之，AMD使用方法和季节变化显著影响了奶牛粪便中 和ES的抗菌药物耐药性。
