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目的检测志贺菌对喹诺酮类药的耐药情况,指导临床合理用药;探讨志贺菌喹诺酮类耐药株gyrA和parC基因的突变,分析GyrA和ParC氨基酸改变与喹诺酮类耐药的关系。方法 2010~2012年从宿州市3家综合性医院收集志贺菌76株,进行分离培养和血清型鉴定;采用K-B纸片法进行药物敏感试验;采用PCR方法检测志贺菌喹诺酮耐药决定区(QRDR)相关gyrA和parC基因,并挑选部分PCR产物进行DNA测序分析。结果收集的76株志贺菌中福氏志贺菌74株(占97.4%),宋内志贺菌2株(占2.6%);药敏结果显示志贺菌耐药情况严重,其中对阿莫西林耐药率最高,达100%;对头孢噻肟耐药率最低,为6.5%。对gyrA基因的序列分析发现3个导致氨基酸改变的基因点突变:Ser83→Leu,Asp87→Gly及His211→Tyr;对parC基因序列分析发现2个导致氨基酸改变的基因点突变:parC Ser80→Ile和Asp197→Asn。结论宿州市志贺菌感染仍以福氏志贺菌为优势菌群,且耐药严重,临床治疗志贺菌感染可优先选择头孢噻肟。志贺菌属对喹诺酮类药物产生耐药性与gyrA和parC基因突变有关,GyrA His211→Tyr和ParC Asp197→Asn氨基酸变异与喹诺酮类耐药的关系需进一步研究。
Objective To detect the resistance of Shigella to quinolones and to guide clinical rational drug use. To investigate the mutations of gyrA and parC genes in quinolone-resistant strains of Shigella and the relationship between the amino acid changes of GyrA and ParC and quinolone resistance. Methods From 2010 to 2012, 76 strains of Shigella were collected from three general hospitals in Suzhou City for isolation, culture and serological identification. Drug susceptibility tests were performed using the KB disk method. The quinolone resistance-determining regions (QRDR) related gyrA and parC genes, and select some PCR products for DNA sequencing analysis. Results Among the 76 strains of Shigella, 74 strains of Shigella flexneri (97.4%) and 2 strains of Shigella sonnei (2.6%) were collected. The susceptibility results showed that Shigella resistance was serious, The highest rate of resistance to moxillin was 100%, and the lowest rate of cefotaxime was 6.5%. Sequence analysis of gyrA gene revealed three point mutations of amino acids: Ser83 → Leu, Asp87 → Gly and His211 → Tyr. Two of the point mutations in the gene encoding parC gene, which resulted in amino acid changes, were: parC Ser80 → Ile and Asp197 → Asn. Conclusion Shigella flexneri infection in Suzhou is still the dominant flora of Shigella flexneri and its drug resistance is serious. Cefotaxime may be the preferred choice for clinical treatment of Shigella infection. The resistance of Shigella to quinolones is related to the mutation of gyrA and parC genes. The relationship between amino acid mutations of GyrA His211 → Tyr and ParC Asp197 → Asn and quinolone resistance needs further study.