不同耐药鲍曼不动杆菌毒力效应检测与分析

Detection and analysis of virulence effects of different drug-resistant Acinetobacter baumannii

目的比较不同耐药性鲍曼不动杆菌毒力特点,探讨鲍曼不动杆菌耐药性与其致病力之间的关系。方法将来自临床的110株鲍曼不动杆菌分成3组:多重耐药鲍曼不动杆菌(MDRAB)、泛耐药鲍曼不动杆菌(XDRAB)和相对敏感鲍曼不动杆菌(RDSAB)。采用PCR检测试验菌株携带的毒力基因(BasD、BauA、Omp33-36、traT);采用吸光度值法测定试验菌株的体外生长情况;采用蹭行运动实验检测试验菌株运动能力;采用明胶酶活性实验检测试验菌株产侵袭性酶类情况;采用结晶紫染色法测定试验菌株生物被膜形成能力;采用微量法D-甘露糖抵抗红细胞凝集实验检测试验菌株对红细胞的凝集能力;采用小鼠感染试验对比不同耐药菌的致病能力差异。结果110株鲍曼不动杆菌中,除了2株RDSAB蹭行运动阳性外,其余菌株均为阴性,MDRAB和XDRAB均未观察到蹭行运动;110株鲍曼不动杆菌全部菌株明胶酶活性均为阴性;25株RDSAB的生物被膜形成能力比42株MDRAB或43株XDRAB的生物被膜形成能力强,差异有统计学意义(P<0.05),其中25株RDSAB生物被膜形成能力以强阳性为主,而42株MDRAB和43株XDRAB以阳性为主;只有1株RDSAB在有或者无D-甘露糖存在的条件下,均能与AB型和O型红细胞发生凝集;毒力基因BasD具有较高的检出率,为59.1%(65/110),毒力基因BauA和Omp33-36检出率较低,分别为6.4%(7/110)和3.6%(4/110),未检出毒力基因traT;MDRAB的BasD毒力基因检出率比RDSAB高,差异有统计学意义(P<0.05),RDSAB的毒力基因Omp33-36检出率比MDRAB和XDRAB高,差异有统计学意义(P<0.05),MDRAB的BasD和BauA毒力基因检出率比XDRAB高,差异有统计学意义(P<0.05)。结论鲍曼不动杆菌在获得耐药性的同时其毒力并没有相应增加,RDSAB的环境生存和定植能力比MDRAB和XDRAB更强。

Objective To compare the virulence characteristics of different drug-resistant Acinetobacter baumannii,and to explore the relationship between the drug resistance of Acinetobacter baumannii and its pathogenicity.Methods A total of 110 clinical strains of Acinetobacter baumannii were divided into 3 groups:multi-drug-resistant Acinetobacter baumannii(MDRAB),extensively-drug-resistant Acinetobacter baumannii(XDRAB)and relatively sensitive Acinetobacter baumannii(RDSAB).PCR was used to detect the virulence genes(BasD,BauA,Omp33-36,traT)carried by the test strains.The absorbance method was used to detect the in vitro growth of the test strains.The rubbing novement test was used to detect the motility of the test strains.The gelatinase activity test was used to detect the production of invasive enzymes by the test strains.The crystal violet staining method was used to detect the biofilm formation ability of the test strains.The micro-method D-mannose resistance to erythrocyte agglutination test was used to detect the ability of the test strains to agglutinate erythrocytes.The mouse infection test was used to compare the pathogenicity of different drug-resistant bacteria.Results Among 110 strains of Acinetobacter baumannii,except for 2 strains of RDSAB that were positive for rubbing movement,the other strains were all negative.No rubbing movement was observed in MDRAB and XDRAB.All 110 strains of Acinetobacter baumannii had negative gelatinase activity.25 strains of RDSAB had stronger biofilm forming ability than 42 strains of MDRAB or 43 strains of XDRAB,and the differences were statistically significant(P<0.05),among them,25 strains of RDSAB had strong positive biofilm formation ability,while 42 strains of MDRAB and 43 strains of XDRAB were mainly positive.Only one RDSAB could agglutinate with AB and O red blood cells in the presence or absence of D-mannose.The virulence gene BasD had a high detection rate of 59.1%(65/110),the detection rates of virulence genes BauA and Omp33-36 were low,6.4%(7/110)and 3.6%(4/110)respectively,and no virulence gene traT was detected.The detection rate of basd virulence gene in MDRAB was higher than that in RDSAB(P<0.05).The detection rate of Omp33-36 virulence gene in RDSAB was higher than that in MDRAB and XDRAB(P<0.05).The detection rate of BasD and BauA virulence gene in MDRAB was higher than that in XDRAB(P<0.05).Conclusion Acinetobacter baumannii acquires drug resistance while its virulence does not increase correspondingly.The environmental survival and colonization ability of RDSAB is stronger than that of MDRAB and XDRAB.