一个高体细胞数牧场奶牛隐性乳腺炎病原菌的调查

对安徽某规模牧场随机采集的314份奶样进行细菌分离鉴定、牛奶体细胞计数(SCC),并对分离比例较高的凝固酶阴性葡萄球菌(CNS)进行亚种鉴定及药敏试验。结果显示120个低体细胞数奶样(SCC25×104/mL)的细菌检出率只有8.3%,分离细菌为CNS;而194个高体细胞数奶样(SCC≥25×104/mL)细菌检出率高达72.2%,分离出的细菌主要为金黄色葡萄球菌、CNS、大肠杆菌、停乳链球菌等。其中CNS感染比例最高、为28.8%,主要包括松鼠葡萄球菌、表皮葡萄球菌、人型葡萄球菌等。乳腺内细菌感染可引起患病乳区SCC显著升高(P0.05),松鼠葡萄球菌和表皮葡萄球菌感染也可引起SCC显著升高(P0.05),不同亚种的CNS对临床常用抗菌药物青霉素、庆大霉素、红霉素有较高的耐药率,分别为71.2%、53.8%和82.7%。

Investigation on Pathogenic Bacteria Causing Subclinical Mastitis on a Dairy Farm with High Somatic Cell Counts

Milk samples（314） were randomly collected from a dairy farm in Anhui Province. The main mastitis-causing pathogens were isolated and identified, and the milk somatic cell counts（SCC） were detected. The sub-species and drug resistance of Coagulose-negcaive staphylococci（CNS） with high proportion were studied. The results showed that only 8.3% of 120 milk samples with low SCC（SCC〈25×10^4 cells/mL）was bacteria（CNS） isolated. While the rate of 194 milk samples with high SCC（SCC≥25×10^4cells/mL）was as high as 72.2%, including Staphykococcus aureus, CNS, E. coli, Streptococcus dysgalactiae and so on. CNS was the most frequently isolated（28.8%）, mainly as Staphylococci sciuri, Staphylococci epidermidis, Staphylococci hominis. The milk samples＇ SCC of pathogen infection udder was significantly higher（P〈0.05） than that of health udder, Staphylococci sciuri and Staphylococci epidermidis infection can also cause the SCC significantly higher（P〈0.05）. And different sub-types of CNS have a higher resistance rate to clinical antimicrobial agent, 71.2%, 53.8%, 82.7% for penicillin, gentamicin, erythromycin respectively.