Moawad Amira A, El-Adawy Hosny, Linde Jörg, Jost Ines, Tanja Gärtner, Katja Hruschka, Karsten Donat, Neubauer Heinrich, Monecke Stefan, Tomaso Herbert
Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany.
Animal Health Research Institute, Agriculture Research Center (ARC), Giza, Egypt.
Front Microbiol. 2023 Aug 25;14:1216850. doi: 10.3389/fmicb.2023.1216850. eCollection 2023.
Bovine mastitis is a common disease of dairy cattle causing major economic losses due to reduced yield and poor quality of milk worldwide. The current investigation aimed to gain insight into the genetic diversity, antimicrobial resistance profiles and virulence associated factors of () isolated from clinical bovine mastitis in dairy farms in Thuringia, Germany.
Forty isolates collected from clinical bovine mastitis cases from 17 Thuringian dairy farms were phenotyped and genetically characterized using whole genome sequencing.
Out of 40 , 30 (75%) were confirmed as methicillin resistant isolates. The isolates showed elevated antimicrobial resistance against penicillin, tetracycline and oxacillin, i.e., 77.5, 77.5, and 75%, respectively. Lower resistance rates were found against moxifloxacin, ciprofloxacin, gentamicin and trimethoprim/sulfamethoxazole, i.e., 35, 35, 30, and 22.5%, respectively. While resistance against clindamycin and erythromycin was rarely found (5 and 2.5%, respectively). All isolates were susceptible to linezolid, teicoplanin, vancomycin, tigecycline, fosfomycin, fusidic acid and rifampicin. These isolates were further allocated into five different sequence types: ST398 ( = 31), ST1074 ( = 4), ST504 ( = 3), ST582 (CC15) ( = 1) and ST479 ( = 1). These isolates were also assigned to seven clusters with up to 100 SNP which has facilitated geographical mapping and epidemiological distribution in Thuringia. Strains belonging to ST398 were classified into clusters 1, 2, 3, 4 and 7. The isolates of ST504 were of cluster 5, those of ST1074 were belonging to cluster 6. Resistance genes Z, I and R associated with penicillin resistance were found in 32 (80%) strains, all except one were belonging to ST398. Methicillin resistance associated A was identified in 30 (96.8%) isolates of ST398. All tetracycline and erythromycin resistant isolates were of ST398, and all harbored both M and A. About 90.3% of tetracycline resistant isolates assigned to ST398 were also carrying K gene. The point mutations C_S80F, A_S84L and C_S80Y in A and C associated with quinolone resistance were found in all phenotypically resistant isolates to ciprofloxacin and moxifloxacin ( = 14). Sixty-eight virulence genes were identified among isolates. Both D/E and /F-PV-P83 were identified in 22.5% of isolates, all were non-ST398.
In this study, ST398 had the highest potential to cause disease and had a massive prevalence in bovine mastitis cases. Five different sequence types and seven clusters were identified in the federal state of Thuringia. The circulation of some clusters in the same region over several years shows the persistence of cluster-associated infection despite the intensive veterinary care. On the other hand, some regions had different clusters at the same year or in different consecutive years. Different sequence types and associated different clusters of were geographically widely distributed among dairy farms in Thuringia. The findings of this study show that various clusters have the potential to spread over a large geographical scale. The detection of LA-MRSA on dairy farms, which is known for cabapility to widely spread among different groups of animals, humans and their environment urges for the implementation of national wide strategic programs. The identification of CA-MRSA among the isolates such as ST398 poses a significant risk for the transmission of such strains between animals and humans on dairy farms.
牛乳腺炎是奶牛的一种常见疾病，在全球范围内，由于产奶量减少和牛奶质量差而造成重大经济损失。当前的调查旨在深入了解从德国图林根州奶牛场临床牛乳腺炎中分离出的（）的遗传多样性、抗菌药物耐药性谱和毒力相关因素。
从图林根州17个奶牛场的临床牛乳腺炎病例中收集了40株（），通过全基因组测序对其进行表型分析和基因特征鉴定。
在40株（）中，30株（75%）被确认为耐甲氧西林菌株。这些菌株对青霉素、四环素和苯唑西林的耐药性升高，分别为77.5%、77.5%和75%。对莫西沙星、环丙沙星、庆大霉素和甲氧苄啶/磺胺甲恶唑的耐药率较低，分别为35%、35%、30%和22.5%。而对克林霉素和红霉素的耐药性很少见（分别为5%和2.5%）。所有菌株对利奈唑胺、替考拉宁、万古霉素、替加环素、磷霉素、夫西地酸和利福平敏感。这些菌株进一步被分为五种不同的序列类型：ST398（=31）、ST1074（=4）、ST504（=3）、ST582（CC15）（=1）和ST479（=1）。这些菌株还被分为七个簇，最多有100个单核苷酸多态性，这有助于在图林根州进行地理定位和流行病学分布研究。属于ST398的菌株被分类到簇1、2、3、4和7中。ST504的菌株属于簇5，ST1074的菌株属于簇6。在32株（80%）菌株中发现了与青霉素耐药性相关的耐药基因Z、I和R，除一株外，其余均属于ST398。在ST398的30株（96.8%）分离株中鉴定出与耐甲氧西林相关的A。所有耐四环素和红霉素的分离株均为ST398，且均携带M和A。分配到ST398的耐四环素分离株中约90.3%也携带K基因。在所有对环丙沙星和莫西沙星表型耐药的分离株（=14）中发现了与喹诺酮耐药性相关的A和C中的点突变C_S80F、A_S84L和C_S80Y。在分离株中鉴定出68个毒力基因。在22.5%的分离株中同时鉴定出D/E和/F-PV-P83，均为非ST398。
在本研究中，ST398引起疾病的可能性最高，在牛乳腺炎病例中大量流行。在图林根州识别出五种不同的序列类型和七个簇。尽管有密集的兽医护理，但一些簇在同一地区持续数年的循环表明与簇相关的感染持续存在。另一方面，一些地区在同一年或连续不同年份有不同的簇。不同的序列类型和相关的不同簇在图林根州的奶牛场中地理分布广泛。本研究结果表明，各种簇有可能在大地理范围内传播。在以能够在不同动物群体、人类及其环境中广泛传播而闻名的奶牛场中检测到LA-MRSA，促使实施全国性战略计划。在分离株如ST398中鉴定出CA-MRSA，对奶牛场动物和人类之间传播此类菌株构成重大风险。
