Karell J, Petzl W, Gangl A, Huber-Schlenstedt R, Sorge U S
Department of Udder Health and Milk Quality, Bavarian Animal Health Services, 85586 Poing, Germany; Center for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.
Center for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.
J Dairy Sci. 2024 Jun;107(6):3802-3812. doi: 10.3168/jds.2023-23997. Epub 2023 Nov 16.
The objective of this study was to describe the in vitro resistance of Staphylococcus aureus from bovine quarter milk samples obtained by the udder health laboratory of the Bavarian Animal Health Services between 2012 and 2022. All S. aureus samples were tested for β-lactamase production and only forwarded to further microbroth susceptibility testing either if the β-lactamase result was positive or upon explicit request by the submitter. The growth of most S. aureus isolates was inhibited at the lowest evaluated minimum inhibitory concentration (MIC) of tested antimicrobials, with the MIC and MIC (the MIC where 50% and 90% of isolates were inhibited by the tested antibiotics, respectively) mostly beneath the respective breakpoint. On average, about one-fourth (24%, n = 5,718) of tested isolates was resistant to erythromycin. However, the prevalence of resistant isolates dropped from 53% (n = 1,018) in 2012 to 8% (n = 113) in 2022. The second highest prevalence of in vitro resistance was to penicillin (17%, of all isolates tested for β-lactamase production, n = 28,069). Less than 14% of isolates were resistant to the remaining assessed antimicrobial agents (cefoperazone, pirlimycin, kanamycin-cefalexin, marbofloxacin, amoxicillin-clavulanate, cefquinome, or cefazolin, respectively). Over the years, 4% (n = 959) of the S. aureus isolates selected for microbroth susceptibility testing (and 0.8% (n = 1,392) of all submitted S. aureus isolates) were methicillin-resistant S. aureus, and 5% (n = 1,162) of S. aureus isolates were multidrug resistant. However, there was an overall trend toward fewer resistant isolates. These findings are consistent with those of several European monitoring programs that reported a slight decrease of antimicrobial resistance (AMR) of bovine S. aureus in countries where antibiotic use in veterinary medicine was reduced. Notably, isolates of clinical mastitis cases were consistently less likely to express in vitro resistance than isolates obtained from milk of healthy cows or subclinical mastitis cases. In conclusion, AMR of S. aureus was decreasing and penicillin should remain the first-choice antimicrobial in the attempt of treating S. aureus intramammary infections in Bavaria.
本研究的目的是描述2012年至2022年期间巴伐利亚动物卫生服务机构乳房健康实验室从牛乳房乳样中分离出的金黄色葡萄球菌的体外耐药性。所有金黄色葡萄球菌样本均进行了β-内酰胺酶产生检测，只有当β-内酰胺酶检测结果为阳性或提交者明确要求时，才会进一步进行微量肉汤药敏试验。在测试抗菌药物的最低评估最低抑菌浓度（MIC）下，大多数金黄色葡萄球菌分离株的生长受到抑制，MIC和MIC₅₀（分别为50%的分离株被测试抗生素抑制时的MIC）大多低于各自的折点。平均而言，约四分之一（24%，n = 5718）的测试分离株对红霉素耐药。然而，耐药分离株的比例从2012年的53%（n = 1018）降至2022年的8%（n = 113）。体外耐药性第二高的是青霉素（在所有进行β-内酰胺酶产生检测的分离株中为17%，n = 28069）。不到14%的分离株对其余评估的抗菌药物（分别为头孢哌酮、吡利霉素、卡那霉素-头孢氨苄、马波沙星、阿莫西林-克拉维酸、头孢喹肟或头孢唑林）耐药。多年来，在选择进行微量肉汤药敏试验的金黄色葡萄球菌分离株中，4%（n = 959）（在所有提交的金黄色葡萄球菌分离株中为0.8%，n = 1392）为耐甲氧西林金黄色葡萄球菌，5%（n = 1162）的金黄色葡萄球菌分离株为多重耐药。然而，总体趋势是耐药分离株数量减少。这些发现与几个欧洲监测项目的结果一致，这些项目报告称，在兽药抗生素使用减少的国家，牛金黄色葡萄球菌的抗菌药物耐药性（AMR）略有下降。值得注意的是，临床乳腺炎病例的分离株在体外表达耐药性的可能性始终低于从健康奶牛的牛奶或亚临床乳腺炎病例中获得的分离株。总之，金黄色葡萄球菌的AMR正在下降，在巴伐利亚治疗金黄色葡萄球菌乳房内感染时，青霉素应仍然是首选抗菌药物。
