Lam T J, Schukken Y H, van Vliet J H, Grommers F J, Tielen M J, Brand A
Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
Am J Vet Res. 1997 Jan;58(1):17-22.
To evaluate the effect of natural udder infection with minor pathogens on subsequent natural infection with major pathogens.
7 dairy herds with low bulk milk somatic cell count.
During a 20-month prospective study, milk samples were collected from diary cows at regular intervals and from quarters with clinical signs of mastitis. Incidence of intramammary infection was calculated in uninfected quarters and in quarters infected with minor pathogens. A within-cow, matched case-control analysis was used to evaluate the effect of minor pathogens on subsequent infection with major pathogens.
Quarters infected with minor pathogens had higher somatic cell count than did uninfected quarters. In quarters infected with Corynebacterium bovis, the rate of infection with major pathogens was lower, whereas in quarters infected with coagulase-negative Micrococcaceae, the rate of infection with major pathogens was higher than that in uninfected quarters. From the within-cow comparison, it appeared that, in quarters infected with minor pathogens, infection with major pathogens was significantly lower than that in comparable control quarters not infected with minor pathogens.
Minor pathogens have a protective effect against infection with major pathogens. The protective effect of C bovis against subsequent infection with major pathogens appears to be greater than the effect of coagulase-negative Micrococcaceae.
评估轻微病原体自然感染乳腺对随后主要病原体自然感染的影响。
7个散装牛奶体细胞计数低的奶牛群。
在一项为期20个月的前瞻性研究中，定期从奶牛采集牛奶样本，并从有乳腺炎临床症状的乳腺采集样本。计算未感染乳腺和感染轻微病原体的乳腺的乳房内感染发生率。采用奶牛内匹配病例对照分析来评估轻微病原体对随后主要病原体感染的影响。
感染轻微病原体的乳腺体细胞计数高于未感染的乳腺。在感染牛棒状杆菌的乳腺中，主要病原体的感染率较低，而在感染凝固酶阴性微球菌科的乳腺中，主要病原体的感染率高于未感染的乳腺。从奶牛内比较来看，似乎在感染轻微病原体的乳腺中，主要病原体的感染明显低于未感染轻微病原体的可比对照乳腺。
轻微病原体对主要病原体感染具有保护作用。牛棒状杆菌对随后主要病原体感染的保护作用似乎大于凝固酶阴性微球菌科的作用。
