食品中大肠埃希菌的耐药性与质粒图谱研究

Drug resistance and plasmid spectrum of E coli in food

〔目的〕研究深圳市食品中污染的大肠埃希菌的耐药性 ,并分析其与细菌所携带的质粒之间的关系。〔方法〕按国家食品卫生标准方法分离食品中的大肠埃希菌 ,K -B法测定细菌对 19种抗生素的耐药性 ,碱裂解法提取细菌质粒。〔结果〕食品中污染的大肠埃希菌对四环素 ( 68% )、磺胺 ( 5 0 % )、复方新诺明 ( 5 0 % )、氨苄西林 ( 44 % )、萘啶酸( 3 6% )、链霉素 ( 3 4% )和庆大霉素 ( 3 2 % )等耐受性较强 ,而头孢菌素类抗生素特别是三代头孢以及抗菌活性与三代头孢相当的非典型 β -内酰胺类抗生素如头孢美唑和氨曲南较为敏感。 94%的试验菌株对一种以上抗生素耐药 ,74%对两种或两种以上抗生素耐药 ,44 %的菌株对五种以上抗生素耐药 ,最多的达 14种抗生素。但细菌耐药性与其所携带的质粒的数量和大小并无直接联系。〔结论〕食品中大肠埃希菌对多种抗生素都具有耐药性 。

〔Objective〕 To investigate the antibiotic resistance of E coli contaminating the raw meats in Shenzhen city.〔Methods〕 E coli contaminating the raw meats was isolated and identified according to the National Standard Methods for Food-related Bacteria Detection and the antimicrobial susceptibility of the 50 isolates to the 19 antibiotics was determined by the Kirby-Bauer method based on the Performance Standards for Anti-microbial Susceptibility Testing recommended by NCCLS.Then the plasmids of all the multi-drug resistant isolates and some of the single antibiotic resistant isolates were acquired by alkaline-SDS method.〔Results〕 The isolates were high resistant to tetracycline (68%),sulfonamides (50%),sulfamethoxazole (50%),trimethoprim (50%),ampicillin (44%),nal acid (36%),streptomycin (34%) and gentamycin (32%).Of all the isolates,94% were resistant to 1 or more antibiotics,74% over 2 kinds of antibiotics,44% to over 5 kinds of antibiotics and 2 with the highest level of antibiotic resistance were resistant to 14 of the 19 tested antibiotics.However,the number and size of plasmids in each isolate were not directly related to its drug resistance.〔Conclusions〕 The isolates of E coli from raw meats in Shenzhen are resistant to various antibiotics.The number and size of plasmids in each isolate are not directly related to its drug resistance.