Department of Dairy Science, University of Wisconsin, Madison 53706.
Department of Animal Science, Michigan State University, East Lansing 48824.
J Dairy Sci. 2020 Apr;103(4):3479-3492. doi: 10.3168/jds.2019-17464. Epub 2020 Feb 20.
The objective of this study was to describe diversity of Klebsiella pneumoniae isolated from milk collected at detection of nonsevere (abnormal milk or abnormal udder) clinical mastitis (CM) and during a follow-up period. Cases were detected in cows enrolled in a randomized clinical trial (n = 168) conducted using 2 related Wisconsin dairy farms. Cases were randomly assigned to receive 2 d (n = 18) or 8 d (n = 18) of intramammary infusions with an approved product containing ceftiofur hydrochloride or assigned to a negative control group (n = 17). Milk samples were collected from affected quarters at detection and during a 28-d follow-up period. Sufficient DNA was recovered from 53 of 54 Kleb. pneumoniae cultured from quarter milk samples collected at detection of the incident case. Additional Kleb. pneumoniae were recovered from milk samples collected from the same quarters at 14, 21, and 28 d after case detection (n = 35), at detection of recurrent cases in the same quarter (n = 14), and from new cases of CM (n = 3) occurring in enrolled quarters. All Kleb. pneumoniae were used for molecular typing by pulsed-field gel electrophoresis and 90% similarity was used to define homology. Of Kleb. pneumoniae recovered from incident cases, unique strains (n = 41) were identified in milk samples collected from cows on farm A (n = 19) and farm B (n = 22), whereas 12 clonal strains were identified with 8 found only in milk collected from farm A and 4 found in milk samples collected from cows on both farms. Heterogeneous strains of Kleb. pneumoniae genotypes were isolated from incident cases of CM. However, when intramammary infection persisted or when recurrence of CM occurred, clonal strains were isolated at 14, 21, or 28 d. Similar strains of Kleb. pneumoniae genotypes caused persistent CM. In conclusion, initial cases of CM were caused by a wide genetic diversity of Kleb. pneumoniae, but when IMI persisted, the same strain often persisted within the mammary gland up to 28 d.
本研究的目的是描述从非严重（异常乳或异常乳房）临床乳腺炎（CM）检测时和随访期间采集的牛奶中分离出的肺炎克雷伯氏菌的多样性。病例是在参加了在两个相关的威斯康星州奶牛场进行的随机临床试验（n=168）的奶牛中发现的。病例被随机分配接受 2 天（n=18）或 8 天（n=18）的含有盐酸头孢噻呋的批准产品的乳房内输注，或分配到阴性对照组（n=17）。在病例检测时和 28 天的随访期间，从受影响的牛乳房采集奶样。从在检测到病例时从 quarter 牛奶样本中培养出的 54 株肺炎克雷伯氏菌中回收了足够的 DNA。在病例检测后 14、21 和 28 天从同一 quarter 采集的牛奶样本（n=35）、同一 quarter 复发性病例检测（n=14）和牛群中发生的新 CM 病例（n=3）中回收了额外的肺炎克雷伯氏菌。所有肺炎克雷伯氏菌均用于脉冲场凝胶电泳的分子分型，使用 90%相似性来定义同源性。从病例中回收的肺炎克雷伯氏菌中，在农场 A（n=19）和农场 B（n=22）的奶牛的牛奶样本中鉴定出独特的菌株（n=41），而在 8 个仅在农场 A 收集的牛奶中发现 12 个克隆株，在来自两个农场的奶牛的牛奶样本中发现 4 个克隆株。CM 的初始病例分离出了肺炎克雷伯氏菌基因型的异源菌株。然而，当乳腺内感染持续存在或 CM 复发时，在 14、21 或 28 天时分离出了克隆株。CM 持续存在的情况下，相同的肺炎克雷伯氏菌基因型菌株持续存在。总之，CM 的初始病例是由肺炎克雷伯氏菌的广泛遗传多样性引起的，但当 IMI 持续存在时，同一菌株通常在 28 天内持续存在于乳腺中。
