Bedenić Branka, Beader Nataša, Godič-Torkar Karmen, Vranić-Ladavac Mirna, Luxner Josefa, Veir Zoran, Grisold Andrea J, Zarfel Gernot
1Department of Microbiology, School of Medicine, University of Zagreb, Zagreb, Croatia.
2Department of Clinical and Molecular Microbiology, Clinical Hospital Center Zagreb, Zagreb, Croatia.
Microb Drug Resist. 2015 Jun;21(3):270-8. doi: 10.1089/mdr.2014.0157. Epub 2015 Jan 19.
Acinetobacter baumannii is an increasingly common pathogen in healthcare settings globally. It is frequently resistant to multiple antimicrobial agents and there are recent reports on strains that are pandrug resistant. The aim of the study was to characterize the mechanisms of carbapenem resistance of A. baumannii strains from a nursing home in Zagreb and to genotype the strains. Antimicrobial susceptibility testing was performed by the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI). PCR was used to detect genes encoding carbapenemases of groups A, B, and D and extended-spectrum β-lactamases. Genotyping of the strains was performed by rep-PCR. All strains were found to be resistant to ceftazidime, cefotaxime, ceftriaxone, cefepime, piperacillin/tazobactam, imipenem, meropenem, and ciprofloxacin. All, but one strain, were resistant to gentamicin. PCR revealed blaOXA-23 genes in 14, blaOXA-24 in 5, and blaVIM in 11 strains. All strains positive for blaVIM genes coharbored blaOXA-23 genes. The 14 strains with OXA-23 belonged to ICL II, whereas the 5 strains positive for blaOXA-24 belonged to ICL I. In contrast to hospitals where OXA-24/40-like β-lactamases and OXA-58 were the most prevalent, OXA-23-like β-lactamases are the dominant group in the nursing home. OXA-58-like β-lactamase, which is the most widespread group, was not found. Acquisition of blaMBL genes in A. baumannii strains was observed. Rep-PCR identified two clones. Two strains A10 and A13 were alocated to a novel sequence type ST 637. Nursing homes can act as a source of dissemination of blaOXA and blaMBL genes in the environment and the possible influx to the hospital environment.
鲍曼不动杆菌是全球医疗机构中日益常见的病原体。它常常对多种抗菌药物耐药，最近还有关于泛耐药菌株的报道。本研究的目的是鉴定来自萨格勒布一家养老院的鲍曼不动杆菌菌株对碳青霉烯类耐药的机制，并对这些菌株进行基因分型。根据临床和实验室标准协会（CLSI）的方法，采用肉汤微量稀释法进行抗菌药物敏感性试验。使用聚合酶链反应（PCR）检测A、B和D组碳青霉烯酶以及超广谱β-内酰胺酶的编码基因。通过重复聚合酶链反应（rep-PCR）对菌株进行基因分型。所有菌株均对头孢他啶、头孢噻肟、头孢曲松、头孢吡肟、哌拉西林/他唑巴坦、亚胺培南、美罗培南和环丙沙星耐药。除一株外，所有菌株均对庆大霉素耐药。PCR检测发现14株携带blaOXA-23基因，5株携带blaOXA-24基因，11株携带blaVIM基因。所有携带blaVIM基因的菌株均同时携带blaOXA-23基因。14株携带OXA-23的菌株属于国际克隆谱系（ICL）II型，而5株携带blaOXA-24的菌株属于ICL I型。与医院中OXA-24/40样β-内酰胺酶和OXA-58最为常见不同，OXA-23样β-内酰胺酶是养老院中的主要类型。未发现最广泛分布的OXA-58样β-内酰胺酶。观察到鲍曼不动杆菌菌株中blaMBL基因的获得。Rep-PCR鉴定出两个克隆。两株菌株A10和A13被归为一种新的序列类型ST 637。养老院可能成为环境中blaOXA和blaMBL基因传播的源头，并可能流入医院环境。
