南通地区食源性沙门菌多重耐药性与整合子的相关性研究

Correlations research of food- borne Salmonella multi- drug resistanceand integrons in Nantong area

目的通过对南通地区食源性沙门菌整合子的检测及耐药性分析,初步探讨整合子、基因盒与耐药性的相关性。方法采用纸片扩散法(kirby-bauer)对67株食源性沙门菌进行耐药性分析,从中选取多重耐药性菌株,提取纯化不同菌株共有的质粒,应用PCR法扩增整合子并进行分类;随机选取1例PCR产物进行DNA测序。结果 67株南通地区食源性沙门菌中31.3%具有多重耐药性;Ⅰ类整合子阳性14株,未发现Ⅱ类、Ⅲ类整合子;10株沙门菌携带质粒,质粒数目为1个~3个,大小为0.5 kb^4 kb;Gen Bank数据库BLAST软件分析1例PCR产物(1.5 kb片段)含有3个开放阅读框,分别与dfr A1、sat2和aad A1耐药基因盒对应。结论南通地区食源性沙门菌对氨苄西林、环丙沙星和哌拉西林等药物出现较高的耐药性;耐药基因可由Ⅰ类整合子携带,并可通过接合试验发生转移,这对细菌多重耐药性的产生和传播转移起到非常重要的作用。

Objective To explore the correlations of integrons,gene cassettes and drug resistance by detecting and analyzing the integrons of Salmonella isolated from food in Nantong area. Methods Antibiotic susceptibility was tested with the K- B diffusion assay; Plasmids from different Salmonella were extracted and purificated; Integrons were classified and detected by PCR; 1 PCR product was analyzed by DNA sequence randomly. Results Some strains（ 31. 3%） displayed multi- drug resistance characteristic. The detection number of class Ⅰintegron was 14 and none of class,Ⅲ were found. 10 strains of Salmonella carried plasmids. The number of plasmids were between 1 to 3. Their size ranged from 0. 5 kb to 4 kb. 3 ORF were found on the PCR product based on the BLAST analysis by Gen Bank database,which corresponding to dfr A1,sat2 and aad A1 respectively. Conclusion The strains of Salmonella isolated from food in Nantong area showed higher resistance to ampicillin,ciprofloxacin and piperacillin,etc. Resistance gene can be carried by class Ⅰintegron,which transferred by conjugation test. It played a very important role in the production and dissemination of the bacterial multi- drug resistance.