Department of Udder Health and Milk Quality, Bavarian Animal Health Services, 85586 Poing, Germany; Clinic for Ruminants with Ambulatory and Herd Health Services, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University Munich, 85764 Oberschleissheim, Germany.
Clinic for Ruminants with Ambulatory and Herd Health Services, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University Munich, 85764 Oberschleissheim, Germany.
J Dairy Sci. 2024 Oct;107(10):8452-8463. doi: 10.3168/jds.2023-24555. Epub 2024 May 31.
The objective of this study was to analyze the in vitro antimicrobial resistance (AMR) of Streptococcusdysgalactiae, Strep. agalactiae, and Strep. canis over a 10-yr period from 2012 to 2022 against the most commonly used antimicrobial agents. For this purpose, all quarter milk samples (QMS) submitted to the milk laboratory of the Bavarian Animal Health Service were analyzed. Each QMS was tested using the California Mastitis Test and categorized as negative, subclinical, or clinical mastitis if the milk character was abnormal. Samples with Strep. dysgalactiae, Strep. agalactiae, or Strep. canis were included and a subset of isolates were further tested for in vitro AMR by breakpoint analysis with broth microdilution. Streptococcus dysgalactiae (61%, n = 65,750) was the most abundant pathogen among those 3 species, followed by Strep. agalactiae (28%, n = 30,486), and Strep. canis (11%, n = 11,336). All 3 species showed the highest resistance to the same 4 antimicrobial agents: erythromycin, marbofloxacin, pirlimycin, and cefalexin/kanamycin with varying degrees of resistance. Throughout the study period, Strep. dysgalactiae, Strep. agalactiae, and Strep. canis were largely susceptible to the remaining antimicrobial agents tested (penicillin, amoxicillin-clavulanate, oxacillin, cefazolin, cefoperazone, cefquinome). Only less than 14% of isolates of Strep. dysgalactiae and Strep. canis were resistant against any of the antimicrobials tested. Streptococcus agalactiae was the species with the highest percentage of resistant isolates. Although the percentage of resistant isolates from Strep. canis and Strep. dysgalactiae decreased, the percentage of resistant Strep. agalactiae isolates increased after 2017. In summary, most isolates were not resistant to the most commonly used antimicrobial agents for mastitis therapy, including β-lactam antibiotics and penicillin should remain the first-choice therapy against streptococcal mastitis.
本研究的目的是分析 2012 年至 2022 年期间的 10 年间，乳链菌、无乳链球菌和犬链球菌对最常用的抗菌药物的体外抗菌药物耐药性（AMR）。为此，对巴伐利亚动物卫生局牛奶实验室提交的所有季度牛奶样本（QMS）进行了分析。每个 QMS 均采用加利福尼亚乳房炎测试进行检测，如果牛奶特性异常，则将其归类为阴性、亚临床或临床乳腺炎。如果存在乳链菌、无乳链球菌或犬链球菌，则将其纳入样本，并通过肉汤微量稀释法进行体外 AMR 检测，对分离株进行亚组检测。在这 3 种细菌中，乳链菌（61%，n=65750）是最丰富的病原体，其次是无乳链球菌（28%，n=30486）和犬链球菌（11%，n=11336）。这 3 种细菌对相同的 4 种抗菌药物表现出最高的耐药性：红霉素、马波沙星、吡利霉素和头孢氨苄/卡那霉素，耐药程度不同。在整个研究期间，乳链菌、无乳链球菌和犬链球菌对其余测试的抗菌药物大多具有敏感性（青霉素、阿莫西林-克拉维酸、苯唑西林、头孢唑林、头孢哌酮、头孢喹肟）。只有不到 14%的乳链菌和犬链球菌分离株对任何测试的抗菌药物具有耐药性。无乳链球菌是耐药分离株比例最高的物种。尽管无乳链球菌和乳链菌的耐药分离株比例有所下降，但 2017 年后，耐无乳链球菌的分离株比例有所增加。总之，大多数分离株对乳腺炎治疗最常用的抗菌药物没有耐药性，包括β-内酰胺类抗生素和青霉素应仍然是治疗链球菌乳腺炎的首选药物。
