天津地区福氏志贺菌整合子携带及耐药性研究

目的了解天津地区不同年份福氏志贺菌血清型分布,整合子携带情况,耐药性及其变化趋势。方法采用血清学方法对天津地区不同年份分离的56株福氏志贺菌进行分型;PCR扩增整合子整合酶及可变区,并测序;采用K-B法测定其对16种抗菌药物的敏感性。结果 1981~1983年分离株福氏志贺菌1类整合酶阳性率为87.50%(28/32),其中27株可变区含氨基糖苷类药物耐药基因aadA;2009~2011年分离株福氏志贺菌1类整合酶阳性率为91.67%(22/24),可变区及3’末端扩增均阴性。1981~1983年分离株福氏志贺菌2类整合酶均阴性;2009~2011年分离株福氏志贺菌2类整合酶阳性率79.17%(19/24),可变区含dfrA1、sat1、aadA1,介导对甲氧苄啶、链丝菌素和链霉素耐药。有17株福氏志贺菌1、2类整合酶均阳性。1981~1983年分离株福氏志贺菌对四环素、链霉素、氯霉素及甲氧苄啶/磺胺甲噁唑耐药率高,多重耐药率为65.63%;2009~2011年分离株福氏志贺菌对氨苄西林、链霉素、甲氧苄啶/磺胺甲噁唑、哌拉西林和四环素耐药率高,多重耐药率为83.33%。结论 1、2类整合子广泛存在于天津地区福氏志贺菌中,其中1类整合子3’保守末端可能缺失或存在变异。2009~2011年分离株福氏志贺菌对抗菌药物耐药性较1981~1983年分离株增强,多重耐药率增高。福氏志贺菌优势血清型发生转变,血清型分布呈现多样化。

Study on integrons and antibiotic resistance of Shigella flexneri in Tianjin

Objective To investigate changes in the serotype distribution, integrons, and antibiotic resistance of Shigella flexneri at different times in the city of Tianjin. Methods The integrase encoding regions and variable regions of in- tegrons of S. flexneri strains were amplified with PCR and then sequenced. The serotypes of 56 S. flexneri strains, 32 of which were stored in this laboratory and 24 of which were isolated at different times from tertiary hospitals in Tianjin. were identified and tested for their sensitivity to 16 antibiotics using the Kirby Bauer antibiotic testing method. Results Of the 32 strains of S. flexneri isolated from 1981 to 1983 and stored in this laboratory, 28 （87.50%） were found to have a class 1 integron while 27 harbored an aminoglycoside resistance gene, aadA, in the variable region of their inte grons. Isolates from 2009--2011 tested positive for class 1 integrase at a rate of 91.67% （22/24）, but the variable region and 3＇-end amplification were not present in any of the strains. Isolates from 1981--1983 lacked a class 2 integron while 19 （79.17%） of the 24 strains isolated from 2009 2011 possessed a class 2 integron, and the variable region of the inte gron harbored dfrA1 ＋sat1 ＋aadA1 genes, which respectively mediate antibiotic resistance to trimethoprim, streptothri cin, and streptomycin. Seventeen of the 56 total strains possessed both class 1 and 2 integrons. Isolates from 1981 1983 were highly resistant to tetracycline, streptomycin, chloramphenieol, and a combination of trimethoprim and sulfame- thoxazole; 65.63 % of the strains were resistant to 3 or more antibiotics. Isolates from 2009 2011 had high resistance to ampieillin, streptomycin, trimethoprim sulfamethoxazole, piperacillin, and tetracycline; 83. 33% of the strains were multi-resistant. Conclusion Class 1 and 2 integrons are widely present in S. flexneri, and the 3＇- conserved segments of class 1 integrons may have deletions or other types of mutations. Cocnparison of the antibiotic and multidrug resistance of isolates from 1981-- 1983 to the resistance of isolates frocn 2009 2011 revealed that the antibiotic resistance and the in cidence of genes that confer mnltidrug resistance have increased over the years in S. flexneri. The predominant serotype of S. flea＇neri in Tianjin has changed.