title: Nursing Home as a Reservoir of Carbapenem-Resistant Acinetobacter baumannii.
abstract: 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.
authors.affiliation: 1Department of Microbiology, School of Medicine, University of Zagreb, Zagreb, Croatia.|2Department of Clinical and Molecular Microbiology, Clinical Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Branka
authors.initials: B
authors.lastname: Bedenić
authors.affiliation: 1Department of Microbiology, School of Medicine, University of Zagreb, Zagreb, Croatia.|2Department of Clinical and Molecular Microbiology, Clinical Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Nataša
authors.initials: N
authors.lastname: Beader
authors.affiliation: 3Department for Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Karmen
authors.initials: K
authors.lastname: Godič-Torkar
authors.affiliation: 4Department of Microbiology, Public Health Institute of Istria County, Pula, Croatia.
authors.forename: Mirna
authors.initials: M
authors.lastname: Vranić-Ladavac
authors.affiliation: 5Institute for Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Josefa
authors.initials: J
authors.lastname: Luxner
authors.affiliation: 6Department of Surgery, Clinical Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Veir
authors.affiliation: 5Institute for Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Grisold
authors.affiliation: 5Institute for Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Gernot
authors.initials: G
authors.lastname: Zarfel
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D015780:Carbapenems / Q000494:pharmacology; D002999:Clone Cells; D017523:Croatia / Q000453:epidemiology; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006707:Homes for the Aged; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D009735:Nursing Homes; D010802:Phylogeny; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D001618:beta-Lactamases