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为了研究奶牛乳房炎大肠杆菌的青霉素耐药特征,采用药敏纸片法检测了123株大肠杆菌对青霉素的耐药性,并利用β-内酰胺酶试剂盒测定耐青霉素株β-内酰胺酶活性,同时采用刚果红法和改良结晶紫半定量方法检测生物被膜的形成能力。结果表明:123株受试大肠杆菌中,对青霉素耐药的菌株有122株,耐药率99.19%。122株耐青霉素大肠杆菌中,生物被膜检测为阳性的菌株有92株(75.41%),β-内酰胺酶检测为阳性的有72株(59.02%);β-内酰胺酶阳性而生物被膜阴性的菌株有15株(12.30%),β-内酰胺酶和生物被膜同为阳性的有57株(46.72%);β-内酰胺酶为阴性但生物被膜为阳性的菌株有35株(28.69%)。92株生物被膜阳性菌株中,29株(31.52%)具有强成膜能力,61株(66.30%)具有中等成膜能力,2株(2.17%)成膜能力较弱。说明奶牛乳房炎大肠杆菌对青霉素的耐药率较高;大肠杆菌青霉素耐药性受β-内酰胺酶和生物被膜多种因子的共同调控。
In order to study the characteristics of penicillin resistance in Escherichia coli of mastitis in dairy cows, the resistance of 123 Escherichia coli strains to penicillin was tested by the method of drug susceptibility test. The β-lactamase-resistant β-lactamases Activity, at the same time using the Congo red method and modified crystal violet semi-quantitative method to detect biofilm formation ability. The results showed that there were 122 strains resistant to penicillin in 123 strains of Escherichia coli, with a resistance rate of 99.19%. Among 122 strains of penicillin-resistant Escherichia coli, 92 strains (75.41%) were positive for biofilm test, 72 strains (59.02%) were positive for β-lactamase test, β-lactamase-positive and biofilm-negative 15 (12.30%), 57 (46.72%) were positive for β-lactamase and biofilm, 35 were for β-lactamase negative but biofilm was positive (28.69% ). Of the 92 biofilm-positive strains, 29 (31.52%) had strong ability to form membrane, 61 (66.30%) had moderate ability to form membrane and 2 (2.17%) had less ability to form membrane. The results showed that the rate of resistance of E.coli to penicillin in dairy cow was high. The resistance of E. coli to penicillin was regulated by many factors, such as β-lactamase and biofilm.