住院患儿耐碳青霉烯类鲍曼不动杆菌的耐药及生物膜特征分析

Characteristics of drug resistance and biofilm formation in carbapenem-resistantAcinetobacter baumannii in hospitalized children

目的分析住院患儿临床分离的耐碳青霉烯类鲍曼不动杆菌(carbapenem-resistant Acinetobacter baumannii,CRAB)的分布、耐药及生物膜特征,为住院患儿CRAB感染的防治提供参考。方法通过重复回文序列聚合酶链反应将2019年1月—2022年12月分离的48株CRAB分为流行株及散发株,比较这两类菌株耐药及生物膜表型及基因携带情况。结果22株流行株及26株散发株均表现为产D类碳青霉烯酶或产结合下调膜孔蛋白的广谱β-内酰胺酶,且均携带VIM、OXA-23、OXA-51基因。散发株生物膜形成能力强于流行株(P<0.05)。流行株及散发株中均检出生物膜相关Bap、bfs、OmpA、CsuE、intI1基因,其中intI1基因在流行株中的检出率高于散发株(P<0.05)。结论CRAB菌株在医院存在定植,散发株有较强的生物膜形成能力,具备在医院环境中形成新的克隆传播的可能。因此,有必要持续监测CRAB的流行趋势,预警流行株的分布,以降低住院患儿感染CRAB的风险。

Objective To study the distribution,drug resistance,and biofilm characteristics of carbapenem-resistant Acinetobacter baumannii(CRAB)isolated from hospitalized children,providing a reference for the prevention and treatment of CRAB infections in hospitalized children.Methods Forty-eight CRAB strains isolated from January 2019 to December 2022 were classified into epidemic and sporadic strains using repetitive extragenic palindromic sequencebased polymerase chain reaction.The drug resistance,biofilm phenotypes,and gene carriage of these two types of strains were compared.Results Both the 22 epidemic strains and the 26 sporadic strains were producers of Class D carbapenemases or extended-spectrumβ-lactamases with downregulated outer membrane porins,harboring the VIM,OXA-23,and OXA-51 genes.The biofilm formation capability of the sporadic strains was stronger than that of the epidemic strains(P<0.05).Genes related to biofilm formation,including Bap,bfs,OmpA,CsuE,and intI1,were detected in both epidemic and sporadic strains,with a higher detection rate of the intI1 gene in epidemic strains(P<0.05).Conclusions CRAB strains are colonized in the hospital,with sporadic strains having a stronger ability to form biofilms,suggesting the potential for forming new clonal transmissions in the hospital.Continuous monitoring of the epidemic trends of CRAB and early warning of the distribution of epidemic strains are necessary to reduce the risk of CRAB infections in hospitalized children.