MOE Joint International Research Laboratory of Animal Health and Food Safety, Key Laboratory of Physiology and Biochemistry, College of Veterinary Medicine, Nanjing Agricultural Universitygrid.27871.3b, Nanjing, China.
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
Microbiol Spectr. 2022 Dec 21;10(6):e0299722. doi: 10.1128/spectrum.02997-22. Epub 2022 Nov 14.
Klebsiella pneumoniae is an opportunistic pathogen that causes serious infections in humans and animals. However, the availability of epidemiological information on clinical mastitis due to K. pneumoniae is limited. To acquire new information regarding K. pneumoniae mastitis, data were mined about K. pneumoniae strains on dairy cattle farms (farms A to H) in 7 Chinese provinces in 2021. Hypermucoviscous strains of K. pneumoniae were obtained by the string test. MICs of antimicrobial agents were determined via the broth microdilution method. Ten antimicrobial resistance genes and virulence genes were identified by PCR. The prevalence of K. pneumoniae was 35.91% (65/181), and 100% of the bacteria were sensitive to enrofloxacin. Nine antimicrobial resistance genes and virulence genes were identified and compared among farms. The hypermucoviscous phenotype was present in 94.44% of isolates from farm B, which may be a function of the virulence gene. Based on these data, the multidrug-resistant strains SD-14 and HB-21 were chosen and sequenced. Genotypes were assayed for K. pneumoniae isolates from different countries and different hosts using multilocus sequence typing (MLST). Ninety-four sequence types (STs) were found, and 6 STs present a risk for spreading in specific regions. Interestingly, ST43 was observed in bovine isolates for the first time. Our study partially reveals the current distribution characteristics of bovine K. pneumoniae in China and may provide a theoretical basis for the prevention and treatment of bovine K. pneumoniae mastitis. is ubiquitous in nature and infects a wide range of hosts, including animals, and humans. It is one of the leading inducements of clinical mastitis (CM) in dairy cows, a prevalent and costly disease that is predominantly associated with bacterial infection. In general, CM caused by Gram-negative bacteria is more difficult to cure than that associated with Gram-positive pathogens, with an average cost per case of 211.03 U.S. dollars (USD) for Gram-negative bacterial infections compared with 133.73 USD for Gram-positive bacterial CM cases. After Escherichia coli, K. pneumoniae is the second most common Gram-negative cause of bovine CM, but it is the most detrimental in terms of decreased milk yield, discarded milk, treatment costs, death, and culling. In view of the economic implications of K. pneumoniae infection in dairy farming, research into population structure and antibiotic resistance is particularly important.
肺炎克雷伯菌是一种机会性病原体，可导致人类和动物的严重感染。然而，有关肺炎克雷伯菌引起的临床乳腺炎的流行病学信息有限。为了获取有关肺炎克雷伯菌乳腺炎的新信息，我们从 2021 年中国 7 个省份的奶牛养殖场（农场 A 至 H）中挖掘了有关肺炎克雷伯菌菌株的数据。通过 string 试验获得高黏液性肺炎克雷伯菌菌株。通过肉汤微量稀释法测定抗菌药物的 MIC。通过 PCR 鉴定了 10 种抗菌耐药基因和毒力基因。肺炎克雷伯菌的流行率为 35.91%（65/181），所有细菌对恩诺沙星均敏感。在农场之间比较了 9 种抗菌耐药基因和毒力基因。从农场 B 的分离物中 94.44%表现出高黏液性表型，这可能是毒力基因的功能。根据这些数据，选择了多药耐药株 SD-14 和 HB-21 并进行测序。使用多位点序列分型（MLST）对来自不同国家和不同宿主的肺炎克雷伯菌分离物进行基因型分析。发现了 94 种序列型（ST），其中 6 种 ST 存在在特定区域传播的风险。有趣的是，首次在牛源分离物中观察到 ST43。我们的研究部分揭示了中国目前牛源肺炎克雷伯菌的分布特征，为防治牛源肺炎克雷伯菌乳腺炎提供了理论依据。
肺炎克雷伯菌广泛存在于自然界中，感染范围广泛，包括动物和人类。它是奶牛临床乳腺炎（CM）的主要诱因之一，是一种普遍且昂贵的疾病，主要与细菌感染有关。一般来说，革兰氏阴性菌引起的 CM 比革兰氏阳性病原体引起的 CM 更难治愈，革兰氏阴性菌感染的平均每个病例成本为 211.03 美元（USD），而革兰氏阳性 CM 病例的成本为 133.73 美元。仅次于大肠杆菌，肺炎克雷伯菌是引起牛 CM 的第二大常见革兰氏阴性菌，但它对产奶量、废弃奶、治疗成本、死亡和淘汰的影响最大。鉴于肺炎克雷伯菌感染对奶牛养殖业的经济影响，研究其种群结构和抗生素耐药性尤为重要。
