为了解华北地区乳房炎奶样中大肠杆菌的耐药情况，本试验采集华北地区乳房炎奶样240批次，采用EMB培养基和菌悬液法对大肠杆菌进行分离鉴定，通过纸片扩散法对常用的八类29种抗生素进行药敏试验。试验结果表明共分离大肠杆菌17株（7.08%）。药敏试验结果显示大肠杆菌分离株表现出高度耐药和多重耐药。分离株对至少4种抗生素产生耐药性，最多耐药19种，耐药5种以上的菌株较多（58.82%）；针对单一抗生素，分离菌株对青霉素、苯唑西林、林可霉素3种药物耐药率高达100%。针对不同种类抗生素，大肠杆菌分离株对β-内酰胺类药物和林可酰胺类药物的耐药率分别为55.15%，61.76%，均超过半数。本研究旨在发现乳房炎奶样中大肠杆菌的耐药性规律，并根据数据对奶牛乳房炎精准防控，减少牛乳中兽药残留，提升牛乳质量。

In order to investigate the drug resistance of E. coli in the breast milk samples in North China, 240 batches of mastitis milk samples from North China were collected. E. coli was isolated and identified by EMB medium and bacterial suspension method. Susceptibility tests were performed on eight commonly used antibiotics. The results showed that 17 strains (7.08%) of Escherichia coli were isolated. The results of drug susceptibility tests showed that isolated strains of E. coli showed high resistance and multi-drug resistance. The isolated strains were resistant to 4 antibiotics at least, with the most resistant 19 species, and more than 5 resistant strains (58.82%). For single antibiotics, the resistance rate to penicillin, oxacillin, and lincomycin of isolated strains was 100%. For different types of antibiotics, the resistance rates of isolated strains of E. coli to β-lactams and lincosamides were 55.15% and 61.76%, respectively. The objective of this work was to find out the drug resistance of E. coli in milk samples from mastitis. It was helpful to prevent and control cow mastitis according to the data and reduce the residue of veterinary drugs in milk, which would improve the quality of milk.

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）；山东省自然基金青年基金项目（2015ZRB01095）；山东省重点研发计划项目（2016GSF120010）；青岛农业大学高层次人才科研基金项目（6631115043）