Objective: To evaluate the virulence levels of carbapenem-resistant Acinetobacter baumannii ST191, ST195, and ST208, and to analyze the differences in virulence factors among these epidemic clones. Methods: The study involved the genomic sequencing of 233 Acinetobacter baumannii strains that were isolated from the Fifth Medical Center of the Chinese People's Liberation Army General Hospital (North Hospital) between 2011 and 2019. The genomic data was cross-referenced with the Virulence Factor Database (VFDB) to examine the presence of virulence genes in the strains. Furthermore, a Galleria mellonella infection survival model was used to evaluate the virulence levels of the strains, and the association between virulence levels and virulence genes was analyzed. Results: The study included 38 strains of the ST191 clone, 104 strains of the ST195 clone, and 91 strains of the ST208 clone. In the Galleria mellonella infection survival experiment, the average mortality rate for ST191 was 23.0%, with 3 (7.9%) highly virulent strains. For ST195, the average mortality rate was 53.0%, with 34 (32.7%) highly virulent strains. For ST208, the average mortality rate was 47.0%, with 20 (21.9%) highly virulent strains. There was a significant statistical difference in mortality rates between ST191 and ST195 (χ2=13.9, P<0.001) as well as between ST191 and ST208 (χ2=15.2, P<0.001). A comparison of the strains with the VFDB revealed significant differences in the virulence genes carried by the clones. Specifically, the type Ⅵ secretion system-related genes (clpV/tssH, hcp/tssD, tagX, tssA, tssB, tssC, tssE, tssF, tssG, tssK, ssL, tssM) and the sugar transferase gene ACICU_RS00475 were found to be universally absent in ST191 strains (0%) while being prevalent in ST195 (100.0%) and ST208 (>82.0%) strains. Statistical analysis revealed an association between the mortality rate of the clones and the presence of virulence genes(clpV/tssH P<0.001, hcp/tssD P=0.001, tagX P<0.001, tssA P<0.001, tssB P=0.001, tssC P=0.001, tssE P=0.001, tssF P=0.001, tssG P<0.001, tssK P<0.001, tssL P<0.001, tssM P=0.001, ACICU_RS00475 P=0.001). Conclusion: Among the carbapenem-resistant epidemic clones of Acinetobacter baumannii, the ST191 clone shows lower mortality rates in Galleria mellonella, possibly because of the lack of type Ⅵ secretion system and sugar transferase genes.
目的： 对碳青霉烯耐药的鲍曼不动杆菌ST191、ST195和ST208的毒力水平进行分析，探究流行克隆株之间的毒力因子差异。 方法： 对2011—2019年中国人民解放军总医院第五医学中心（北院区）分离的ST191、ST195和ST208共计233株鲍曼不动杆菌进行基因组二代测序，将基因组数据与细菌毒力因子数据库（VFDB）比对，探究菌株的毒力基因存在情况，同时采用大蜡螟感染生存模型评估菌株的毒力水平，采用Kendall′s tau-b等级相关分析菌株毒力水平与毒力基因的相关性。 结果： 共收集鲍曼不动杆菌ST191克隆38株，ST195克隆104株，ST208克隆91株。大蜡螟感染生存试验中ST191平均致死率为23.0%，高毒力菌株有3株（7.9%）；ST195平均致死率为53.0%，高毒力菌株有34株（32.7%）；ST208平均致死率为47.0%，高毒力菌株有20株（21.9%），ST191与ST195（χ2=13.9，P<0.001）和ST208（χ2=15.2，P<0.001）的大蜡螟致死率有显著差异。经比对数据库中7类共120个鲍曼不动杆菌毒力基因，发现克隆株携带的毒力基因具有显著差异，其中Ⅵ型分泌系统相关基因（clpV/tssH、hcp/tssD、tagX、tssA、tssB、tssC、tssE、tssF、tssG、tssK、tssL、tssM）和糖转移酶基因ACICU_RS00475在ST191菌株中普遍缺失（0），相反ST195（99.0%）和ST208（>82.0%）菌株普遍携带此类基因。克隆株的大蜡螟致死率与其携带毒力基因相关（clpV/tssH P<0.001、hcp/tssD P=0.001、tagX P<0.001、tssA P<0.001、tssB P=0.001、tssC P=0.001、tssE P=0.001、tssF P=0.001、tssG P<0.001、tssK P<0.001、tssL P<0.001、tssM P=0.001，ACICU_RS00475 P=0.001）。 结论： 碳青霉烯耐药鲍曼不动杆菌流行株中，ST191的大蜡螟致死率较ST195和ST208低，可能与其Ⅵ型分泌系统和糖转移酶基因的缺失有关。.