武汉地区门诊患者喹诺酮耐药鼠伤寒沙门菌耐药机制分析

目的 研究分析腹泻门诊患者中分离的喹诺酮耐药鼠伤寒沙门菌的耐药机制和遗传关系.方法 对2002-2005年问武汉同济医院腹泻门诊患者中分离的36株喹诺酮耐药鼠伤寒沙门菌进行了耐药谱测定,并通过PCR方法和序列测定对整合子、β内酰胺酶基因、喹诺酮耐药决定区的突变、qnr基因和aac(6')-Ib-cr基因进行了分析,运用脉冲场电泳方法(pulsed-field gel electrophoresis,PFGE)对所收集的菌株进行了分子分型,分析喹诺酮耐药鼠伤寒沙门菌的耐药机制和遗传关系.结果 喹诺酮耐药鼠伤寒沙门菌均为多重耐药株,普遍携带有Ⅰ类整合子,环丙沙星耐药菌株与敏感菌株在PFGE谱型上存在显著性差异,31株环丙沙星耐药菌株在喹诺酮耐药决定区中至少携带GyrA和ParC上的3个点突变,且在这些菌株中均检出了OXA-30基因,这些菌株对头孢吡肟的敏感性出现了不同程度的下降.结论 对环丙沙星耐药的鼠伤寒沙门菌在武汉地区已普遍存在,且这些菌株具有独特的遗传背景,建议在今后的细菌耐药性监测工作中应对这类细菌的耐药谱变化进行重点监测,尤其应加强对氟喹诺酮-三代头孢类抗菌药物均耐药菌株的针对性预警监测.

Antimicrobial resistant mechanisms analysis of outpatient Salmonella enterica serotype Typhimurium in Wuhan

Objective To characterized the Salmonella enterica serotype typhimurium isolates recovered during 2002 to 2005 from outpatients in Tongji Hospital, Wuhan China. Methods The 36 isolates from Tongji Hospital were characterized by antimicrobial-susceptibility testing and screened for class Ⅰ integrons, beta-lactamase genes, qnr, aac(6')-Ib-cr and mutations in the quinolone resistance determining regions (QRDRs) by PCR and DNA sequence analysis. All isolates were also characterized by pulsed-fieldgel electrophoresis (PFGE) to determine the genetic relateness among these isolates. Results All isolates displayed multidrug resistance and most of them harbored class Ⅰ integrons. Ciprofloxacin-resistant isolates showed significant difference compared with ciprofloxacin-susceptible isolates after PFGE analysis. All 31 ciprofloxacin resistant isolates carried at least three mutations in the QRDR of GyrA and ParC. Three ciprofloxacin resistant isolates had accumulated additional mutation in ParE. Five isolates harboring the OXA-30. Enzyme showed intermediate resistant to eefepime. Conclusions Fluoroquinolone-resistant Salmonella typhimurium isolates were widely distributed among the outpatients in Wuhan and the resistant isolates accumulated multiple antimicrobial resistant mechanisms and showed unique genetic profiles. The state and local health authority must remain vigilant for the emergence of Salmonella typhimurium resistant to both third generation cephalosporins and fluoroquinolonos.