天津地区志贺菌耐药性及整合子携带调查

Survey of Antimicrobial Susceptibility and Integron Carriage of Shigella Isolates in Tianjin

目的:了解天津地区志贺菌抗生素耐药性变迁及1、2类整合子携带状况。方法:K-B纸片法测定1981—1983年及2009年天津地区临床分离的57株志贺菌药敏情况。以煮沸法制备细菌总DNA作为PCR扩增模板。PCR方法扩增1、2类整合子整合酶及可变区并测序分析。PCR产物直接测序,结果经BLAST程序与GenBank数据库标准菌株比对分析。结果:1981—1983年组志贺菌对四环素、链霉素、氯霉素及复方新诺明敏感率低,3种及3种以上抗生素多重耐药率为66.67%;2009年组志贺菌对氨苄西林、链霉素、复方新诺明、哌拉西林和四环素敏感率低,3种及3种以上抗生素多重耐药率为83.33%。1981—1983年组1类整合子阳性率为87.88%(29/33),27株可变区含氨基糖苷类药物耐药基因aadA;1株宋内志贺菌可变区含甲氧苄啶耐药基因dfrA17和氨基糖苷类药物耐药基因aadA5;未发现2类整合子阳性株;2009年组1类整合酶阳性率为79.17%(19/24),可变区及3末端扩增均阴性;2类整合子阳性率87.50%(21/24),可变区含dfrA1+sat1+aadA1,介导甲氧苄啶、链丝菌素和链霉素耐药;其中17株1、2类整合酶均阳性。结论:2009年分离的志贺菌抗生素耐药较上世纪80年代分离的志贺菌增强,多重耐药菌株增加。天津地区志贺菌携带1、2类整合子。′

Objective：To investigate changes in antibiotic resistance and carriage of class 1 and class 2 integrons of shigella isolates in Tianjin,China.Methods：A total of 57 clinical isolates of shigella identified in Tianjin during the years of 1981—1983 and 2009 were studied.Antibiotic susceptibility was detected by K-B disk diffusion method.Carriage of class 1 and class 2 integrons was investigated by polymerase chain reaction（PCR） with specific primers and confirmed by restriction endonuclease analysis of amplicons.Results were compared by BLAST program and GenBank database.Results：In the Shigella strains collected during the years of 1981—1983,the sensitive rates to tetracycline,streptomycin,chloromycetin and trimethoprim-sulfamethoxazol were lower,and the multidrug resistant rate was 66.67%.In the other strains collected during the years 2009,the sensitive rates to ampicillin,streptomycin,trimethoprim-sulfamethoxazol,pailaxilin and tetracycline were lower,and the multidrug resistant rate was 83.33%.In the group during the years of 1981—1983,class 1 integrons were found in 87.88%（29/33） of Shigella isolates.Twenty-seven of these integron 1-positive isolates contained gene cassette aadA,which confer resistance.Only the Shigella sonnei isolates contained gene cassette dfrA17＋aadA5 which confer trimethoprim and streptomycin-resistance.None integron 2-positive isolates were found.In the other group during the years 2009,class 1 integrase were found in 79.17%（19/24） of Shigella isolates,however,variable region and 3 conserved segment of class 1 integron were negative in all isolates.Class 2 integrons were present in 87.50%（21/24）of the Shigella isolates.All of these integron 2-positive isolates contained constant gene cassette arrays of dfrA1＋sat1＋aadA1,which confer trimethoprim,streptothricin and streptomycin-resistance to.Both class 1 and class 2 integrase were positive in 17 Shigella isolates.Conclusion：Antibiotic resistance has been developed in the evolution of Shigella strains.Integron carriage was very common in the shigella isolates.