铜绿假单胞菌III型分泌系统相关毒力基因在抗菌药物中表达差异的研究

目的 分析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在抗菌药物中表达的差异性，以期为患者选择合适的抗感染治疗方案及预后评估提供依据。方法 选取南昌大学第二附属医院2017年1月-2017年12月临床分离的铜绿假单胞菌72株，采用Vitek2 Compact全自动微生物鉴定仪进行细菌鉴定及药敏，采用PCR法检测分离菌株T3SS特异性片段popB和相关毒力基因exoS、exoU表达情况；收集患者临床信息，了解毒力基因表达与细菌耐药性的关系。结果 72株铜绿假单胞菌中4种基因型exoS+/exoU-、exoS-/exoU+、exoS+/exoU+和exoS-/exoU-，分别为56.94%、26.39%、4.17%和12.50%，其中痰液、血液标本中检出率最高的基因型为exoS+/exoU-，分别为57.50%(23/40)和70.00%(7/10)。分析药敏结果显示，亚胺培南、氨基糖苷类和氟喹诺酮类耐药的分离株中携带exoU基因的耐药率显著高于携带exoS基因的耐药率，具有统计学意义(P<0.05)；其中携带exoU基因的总菌株为22株，其对亚胺培南、庆大霉素、妥布霉素、阿米卡星、左氧氟沙星及环丙沙星的耐药率分别为45.45%、45.45%、50.00%、50.00%、40.91%和40.91%；携带exoS基因的总菌株为44株，其对以上药物的耐药率分别为4.55%、6.82%、4.55%、18.18%、11.36%和18.18%。结论 我院临床分离的铜绿假单胞菌毒力基因以exoS+/exoU-基因型为主；铜绿假单胞菌携带exoU基因时，显示出对亚胺培南、氨基糖苷类和氟喹诺酮类抗菌药物具有更高的耐药性。

Study on the differential expression of virulence genes by Pseudomonas aeruginosa type III secretion system against antibacterial drugs

Objective To analyze the differential expression of the virulence genes exoS and exoU of type III secretion system at Pseudomonas aeruginosa against antibacterial drugs, and to provide the basis for clinical precise anti-infective treatment and prognosis evaluation. Methods Seventy-two clinically isolated strains of Pseudomonas aeruginosa were collected from the Second Affiliated Hospital of Nanchang University Hospital from January 2017 to December 2017. The Vitek-2 Compact automatic microbiological identification instrument was used to identify and detect the sensitivity to antibacterial drugs. The virulence genes exoU, exoS and characteristic fragment popB of T3SS wereisolated from the strains by PCR. To investigate the relationship between virulence gene expression and drug resistance, the clinical information was collected from patients. Results The detection rates of exoS+/exoU-, exoS-/exoU+, exoS+/exoU+, and exoS-/exoU- were 56.94%, 26.39%, 4.17% and 12.50%, respectively. Among them, the highest genotypes detected in sputum and blood samples were exoS+/exoU-, which were 57.50% (23/40) and 70% (7/10), respectively. By analyzing the susceptibility results, the resistance rates of exoU in imipenem, aminoglycosides and fluoroquinolone resistance isolates were prominently higher than those carrying exoS, and were statistically significant (P<0.05). The total number of strains carrying the exoU gene was 22, and the resistance rates to imipenem, gentamicin, tobramycin, amikacin, levofloxacin, and ciprofloxacin were 45.45%, 45.45%, 50.00%, 50.00%, 40.91% and 40.91%, respectively; while the total number of strains carrying the exoS gene was 44, and the resistance rates to the above drugs were 4.55%, 6.82%, 4.55%, 18.18%, 11.36%, and 18.18%, respectively. Conclusion The virulence genes expression of Pseudomonas aeruginosa in our hospital is mainly exoS+/exoU-genotype. The high detection rate of exoU caused a high rate of drug resistance, in which imipenem, aminoglycoside and fluoroquinolone resistant strains were statistically