为了了解我国奶牛由链球菌引起的乳房炎感染现状，本论文系统地分离鉴定了我国两个地区（东北和西部）170个乳房炎乳的链球菌，并对它们进行了抗生素的耐药性比对。结果表明：我国东北和西部地区的乳房炎乳中分别分离出18株和11株链球菌；药敏试验显示，该两个地区的所有链球菌对29种抗生素药物均表现出不同程度的耐药性，其中，在东北地区链球菌中甲氧苄啶耐药菌（90.0%）、磺胺异噁唑耐药菌（80.0%）、苯唑西林耐药菌（78.5%）、林可霉素耐药菌（74.6%）、克林霉素耐药菌（66.9%）和头孢西丁耐药菌（62.3%）检出率较高；西部地区链球菌检出菌对甲氧苄啶（90.9%）、苯唑西林（81.8%）、青霉素G和磺胺异噁唑（72.7%）耐药性较高；该两个地区的乳房炎乳对抗生素都表现出多重的耐药现象。

The Streptococci was symatically identified in 170 mastitis milks from two areas (northeastern and northeastern) of China, with the aim to understand the present situation of mastitis caused by Streptococci in chinese cow. The drug suceptibility of isolated Streptococci strains against 29 commonly used antibiotics was compared. The results showed that 18 and 11 strains of Streptococcus were isolated from the northeastern and western areas, respectively, and there were differences in drug suceptibility between the northeastern and the western region. All the isolated Streptococci strains showed a drug resistance against 29 kinds of drugs, but to a varying extent. Streptococcus in northeastern region showed a high drug resistance against trimethoprim(90.0%), sulfonamides(80.0%), oxacillin(78.5%), lincomycin(74.6%), clindamycin(66.9%)and cefoxitin (62.3%), while Streptococcus in western region showed a high drug resistance against trimethoprim(90.9%), oxacillin(81.8%), penicillin Gand sulfamethoxazole(72.7%). All the isolated isolated Streptococci strains in both the regions showed multiple drug resistance to antibiotics.

山东省高等学校科学技术计划项目（J17KA131）；农业部公益性农业行业科研专项（201403071-5）；国家奶产品质量安全风险评估重大专项（GJFP201800804）；山东省重点研发计划（2016GSF120010）；山东省优秀中青年科学家科研奖励基金项目（BS2014NY011）；青岛农业大学高层次人才科研基金项目（6631115043）