Laboratory of Bacterial Diseases (LDBAC), Veterinary Department, Universidade Federal de Vicosa (UFV), PH Rolfs Avenue, s/n, University Campus, Viçosa, Minas Gerais, 36570-900, Brazil.
Laboratory of Microbiology and animal immunology, Animal Science Department, Universidade Federal do Vale do São Francisco (UNIVASF), José de Sá Maniçoba Street, Center, Petrolina, Pernambuco, 56306-410, Brazil.
BMC Microbiol. 2020 May 24;20(1):127. doi: 10.1186/s12866-020-01793-9.
Staphylococcus aureus is one of the main causative agents of mastitis in small ruminants. Antimicrobial use is the major treatment, but there are many flaws linked to resistance, tolerance or persistence. This study aimed to verify changes in resistance, virulence and clonal profiles of S. aureus isolated from persistent mastitis goat milk before and after enrofloxacin treatment.
MIC increased to at least one antimicrobial in S. aureus isolates after enrofloxacin treatment compared to before. The most detected resistance genes before and after treatment were tetK, tetM, and blaZ, with more resistance genes detected after enrofloxacin treatment (p < 0.05). Occasional variations in efflux system gene detection were observed before and after treatment. Nine virulence genes (hla, fnbA, fnbB, eta, etb, sea, sec, seh, and sej) were detected at both times, and between these, the hla and eta genes were detected more in isolates after treatment. All isolates of S. aureus belonged to the same sequence type (ST) 133, except for two S. aureus isolates prior to enrofloxacin treatment which were classified as ST5 and the other as a new one, ST4966. Isolates of S. aureus 4, 8, and 100 from before and after treatment had identical pulse types, while others obtained from other animals before and after treatment were classified into distinct pulse types.
There were occasional changes in the studied profiles of S. aureus isolated before and after treatment of animals with enrofloxacin, which may have contributed to the permanence of bacteria in the mammary gland, even when using traditional treatment, resulting in persistent mastitis.
金黄色葡萄球菌是小反刍动物乳腺炎的主要病原体之一。抗菌药物的使用是主要的治疗方法，但存在许多与耐药性、耐受性或持久性相关的缺陷。本研究旨在验证恩诺沙星治疗前后从持续性乳腺炎山羊奶中分离的金黄色葡萄球菌的耐药性、毒力和克隆谱的变化。
与治疗前相比，恩诺沙星治疗后金黄色葡萄球菌分离株的 MIC 至少对一种抗菌药物增加。治疗前后最常检测到的耐药基因是 tetK、tetM 和 blaZ，治疗后检测到更多的耐药基因（p<0.05）。治疗前后偶尔观察到外排系统基因检测的变化。两次均检测到 9 个毒力基因（hla、fnbA、fnbB、eta、etb、sea、sec、seh 和 sej），其中 hla 和 eta 基因在治疗后分离株中检测到更多。所有金黄色葡萄球菌分离株均属于同一序列型（ST）133，除了恩诺沙星治疗前的两个金黄色葡萄球菌分离株分别归类为 ST5 和另一个新的 ST4966。治疗前后金黄色葡萄球菌 4、8 和 100 号分离株的脉冲类型相同，而其他来自治疗前后其他动物的分离株则归类为不同的脉冲类型。
在使用传统治疗方法的情况下，即使在使用传统治疗方法的情况下，金黄色葡萄球菌的研究谱在治疗前后也存在偶尔的变化，这可能导致细菌在乳腺中持续存在，从而导致持续性乳腺炎。
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