Mycoplasma bovis is a major cause of bovine mastitis. Intermittent shedding of the organism for many months is a feature of cows with intramammary infection. A dairy farm in Japan experienced a mastitis outbreak caused by M. bovis in 2016, as well as 2 additional outbreaks and 1 case in 2020–2021. The causative strains in the 3 outbreaks shared a common and identical genetic feature, the insertion of a transposase gene at the same site within the phosphate acetyltransferase-2 gene. Additionally, all isolates were genotyped to closely related sequence types (ST21 and ST141) by multilocus sequence typing, and had similar pulsopatterns by pulsed-field gel electrophoresis. Our results indicate that infection with the same causative strain remained in this herd and environment for 4 y. Treatment with fluoroquinolones, guided by antimicrobial susceptibility test results, eliminated M. bovis from 16 of 20 M. bovis–infected cows, as confirmed by culture and somatic cell counts. However, mastitis caused by other bacteria occurred in 9 M. bovis–free cows within 2 mo of the last treatment.

中文翻译：

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由特定牛支原体菌株引起的牛乳腺炎的暴发每年反复发生

牛支原体是牛乳腺炎的主要原因。数月内间歇性地排出微生物是患有乳房内感染的奶牛的一个特征。日本的一个奶牛场在 2016 年爆发了由牛支原体引起的乳腺炎，并在 2020 年至 2021 年期间又爆发了 2 次疫情和 1 例病例。3 次爆发的致病菌株具有共同且相同的遗传特征，即在磷酸乙酰转移酶 2 基因的同一位点插入转座酶基因。此外，通过多位点序列分型，所有分离株均被基因分型为密切相关的序列类型（ST21 和 ST141），并且通过脉冲场凝胶电泳具有相似的脉冲模式。我们的结果表明，相同致病菌株的感染在该牛群和环境中持续了 4 年。培养和体细胞计数证实，在抗菌药物敏感性测试结果的指导下，用氟喹诺酮类药物治疗，从 20 头感染牛支原体的奶牛中，有 16 头消除了牛支原体。然而，在最后一次治疗后 2 个月内，9 头不含牛分枝杆菌的奶牛出现了由其他细菌引起的乳腺炎。