铜绿假单胞菌T3SS和T6SS的基因分布特性及与耐药的相关性

目的：了解痰液及血液来源铜绿假单胞菌III型分泌系统（T3SS）和VI型分泌系统（T6SS）的基因分布特性及其与耐药的相关性。方法：收集2016年至2018年温州医科大学附属第一医院住院患者中不同标本来源的铜绿假单胞菌共92 株（痰液来源61株，血液来源31株）；PCR法检测菌株T3SS效应蛋白基因exoS、exoT 、exoU 、exoY 、pscC 和T6SS效应蛋白基因tssB1、tse1、tse2 、tse3 、tssB2 、pldA 、tssB3 、pldB 的携带情况；琼脂稀释法检测菌株对临床常用抗菌药物的敏感性；统计分析不同感染与分泌系统基因携带情况的关联性，并进一步分析不同基因与耐药的关系。结果：痰液及血液来源的菌株中T3SS蛋白基因exoT 以及T6SS蛋白基因tssB1、tse2 、tssB2 、pldB 的检出率均高达90%以上，痰液来源菌株T3SS蛋白基因exoU 的携带率（32.8%）显著高于血液来源菌株的携带率（9.7%），差异有统计学意义（P ＜0.05），其对亚胺培南的耐药率也显著高于血液来源菌株（P ＜0.05）；Spearman相关性分析结果表明exoU 和pldA 之间存在正相关（r =0.474，P ＜0.01）；携带不同T3SS及T6SS基因的菌株对临床常用抗菌药物亚胺培南、环丙沙星、头孢他啶、阿米卡星的耐药率差异无统计学意义（P ＞0.05）。结论：T6SS效应蛋白基因pldA 与T3SS效应蛋白基因exoU具有较强的正相关性，常同时存在于铜绿假单胞菌中；痰液和血液来源铜绿假单胞菌T3SS效应蛋白编码基因exoU 的携带率和对亚胺培南的耐药率存在明显差异，提示我们要及时检测T6SS效应蛋白基因pldA 在菌株中的分布，关注菌株致病特性，并关注痰液来源菌株的毒力及耐药性情况，为临床用药及治疗提供策略。

Distribution characteristics of Pseudomonas aeruginosa T3SS and T6SS and their correlation with drug resistance

Objective: To understand the Type III secretion system (T3SS) and Type VI secretion system(T6SS) gene distribution characteristics of Pseudomonas aeruginosa (P. aeruginosa) from sputamentum and blood and their correlation with drug resistance. Methods: A total of 92 strains of P. aeruginosa (61 strains isolated from sputamentum, and 31 strains isolated from blood) in the First Affiliated Hospital of Wenzhou Medical University were collected from 2016 to 2018. The PCR method was used to detect the T3SS effector protein encoding genes exoS, exoT, exoU, exoY and pscC and the T6SS effector protein encoding genes tssB1, tse1, tse2,tse3, tssB2, pldA, tssB3, and pldB. The agar dilution method was used to detect the sensitivity of the strains to commonly used clinical antibacterial drugs. The correlation between different infections and the carrying status of genes encoded by the secretory system was investigated, and further analysis of their relationship with drugresistance was made. Results: The detection rate of T3SS protein encoding gene exoT and T6SS protein genestssB1, tse2, tssB2, and pldB in sputamentum and blood was as high as > 90%. In addition, the carrying rate of T3SS protein gene exoU in strain from sputum was significantly higher than from blood (P<0.05), and thedrug resistance rate of strains to imipenem derived from sputum was significantly higher than those from blood (P<0.05). Spearman correlation analysis showed exoU was positively correlated to pldA (r=0.474, P<0.01).There was no significant difference among strains with different T3SS and T6SS gene profiles against commonlyantibiotics (P>0.05). Conclusion: The pldA gene often coexists with the virulence gene exoU in P. aeruginosa. The carrying rate of T3SS effector protein encoding gene exoU and the resistance against imipenem in P. aeruginosa from sputum is significantly higher than that of strains from blood.