铜绿假单胞菌毒力基因exoS、exoU临床分布及耐药性研究

Distribution and drug-resistance of virulence gene exoS and exoU in Pseudomonas aeruginosa

目的:了解临床分离铜绿假单胞菌Ⅲ型分泌系统(type Ⅲ secretion system,T3SS)毒力基因exoS、exoU的分布特征及耐药特点,为铜绿假单胞菌感染的治疗与控制提供参考。方法:收集2015年9月至2016年3月临床送检标本,分离鉴定铜绿假单胞菌,液体稀释法进行药敏试验,PCR技术检测分离菌株exoS、exoU基因,并对结果进行统计分析。结果:exoS、exoU基因检出率分别为85.71%(54/63)、65.08%(41/63)。4种基因型exoS+/exoU+、exoS+/exoU-、exoS-/exoU+和exoS-/exoU-的阳性率分别为53.97%、31.75%、11.11%和3.17%。呼吸道标本检出率最高的基因型是exoS+/exoU+(60.87%),泌尿道以exoS+/exoU-为主(57.14%)。多重耐药菌exoS、exoU阳性率为80.95%、76.19%,非多重耐药菌阳性率为88.10%、59.52%,比较无显著性差异(p>0.05)。exoS+/exoU+基因型菌株耐药率较高,对亚胺培南和左氧氟沙星耐药性明显高于其他菌株(p<0.05)。结论:临床分离铜绿假单胞菌毒力基因exoS、exoU携带率较高,以exoS+/exoU+基因型为主,基因型表达存在感染部位差异。多重耐药菌与非多重耐药菌基因表达无显著性差异,但同时携带两种毒力基因菌株耐药性强。

OBJECTIVE To investigate distribution features of the virulence gene exoS and exoU of type Ⅲ secretion system（T3SS）and drug resistance of Pseudomonas aeruginosain order to provide a reference for control and treatment.METHODSSpecimens were collected from September 2015 to March2016.Pseudomonas aeruginosastrains were isolated and identified,the drug sensitive test was finished by liquid dilution method,then exoS and exoU genes were detected with PCR technique.Finally,experimental results were statistically analyzed.RESULTS exoS and exoU gene detection rates were 85.71%（54/63）and65.08%（41/63）.There were four genotypes：exoS ＋/exoU ＋,exoS ＋/exoU -,exoS -/exoU ＋ and exoS -/exoU -,their positive rates were 53.97%,31.75%,11.11% and 3.17%,respectively.The highest of genotype was exoS ＋ /exoU ＋（60.87%）in respiratory specimen,and exoS ＋/exoU -（57.14%）in Urinary tract.The positive rates of exoS and exoU were80.95% and 76.19% of multiple drug-resistant bacteria,the other groups of single drug-resistant bacteria were 88.10% and59.52%,no significant difference was found between two groups（P〉0.05）.Resistant rate of genotype exoS ＋ /exoU ＋strains was higher than other types,and significantly higher for imipenem and levofloxacin（P〈0.05）.CONCLUSION In clinical strains of Pseudomonas aeruginosa,gene exoS and exoU carrying rates are higher,exoS ＋ /exoU ＋is the main genetpye.The positive rates of genetpye have no significant difference between the multiple drug-resistant strains and the single drug-resistant strains,but the strains carrying two virulence genes have stronger resistance.