title: Molecular analysis of vanA outbreak of Enterococcus faecium in two Warsaw hospitals: the importance of mobile genetic elements.
abstract: Vancomycin-resistant Enterococcus faecium represents a growing threat in hospital-acquired infections. Two outbreaks of this pathogen from neighboring Warsaw hospitals have been analyzed in this study. Pulsed-field gel electrophoresis (PFGE) of SmaI-digested DNA, multilocus VNTR analysis (MLVA), and multilocus sequence typing (MLST) revealed a clonal variability of isolates which belonged to three main lineages (17, 18, and 78) of nosocomial E. faecium. All isolates were multidrug resistant and carried several resistance, virulence, and plasmid-specific genes. Almost all isolates shared the same variant of Tn1546 transposon, characterized by the presence of insertion sequence ISEf1 and a point mutation in the vanA gene. In the majority of cases, this transposon was located on 50 kb or 100 kb pRUM-related plasmids, which lacked, however, the axe-txe toxin-antitoxin genes. 100 kb plasmid was easily transferred by conjugation and was found in various clonal backgrounds in both institutions, while 50 kb plasmid was not transferable and occurred solely in MT159/ST78 strains that disseminated clonally in one institution. Although molecular data indicated the spread of VRE between two institutions or a potential common source of this alert pathogen, epidemiological investigations did not reveal the possible route by which outbreak strains disseminated.
authors.affiliation: National Medicines Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Wardal
authors.affiliation: National Medicines Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Markowska
authors.affiliation: National Medicines Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Zabicka
authors.affiliation: Institute of Hematology and Transfusion Medicine, ul. Ghandi 14, 02-776 Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Wróblewska
authors.affiliation: Institute of Hematology and Transfusion Medicine, ul. Ghandi 14, 02-776 Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Giemza
authors.affiliation: Institute of Hematology and Transfusion Medicine, ul. Ghandi 14, 02-776 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Mik
authors.affiliation: Institute of Oncology, ul. Roentgena 5, 02-781 Warsaw, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Połowniak-Pracka
authors.affiliation: Institute of Oncology, ul. Roentgena 5, 02-781 Warsaw, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Woźniak
authors.affiliation: National Medicines Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland.
authors.forename: Waleria
authors.initials: W
authors.lastname: Hryniewicz
authors.affiliation: National Medicines Institute, ul. Chełmska 30/34, 00-725 Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Sadowy
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D019729:Carbon-Oxygen Ligases / Q000235:genetics* / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics*; D004196:Disease Outbreaks; D004352:Drug Resistance, Microbial / Q000187:drug effects / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D005798:Genes, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology*; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D011044:Poland / Q000453:epidemiology; D014640:Vancomycin / Q000494:pharmacology; D014774:Virulence / Q000187:drug effects / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; C071437:VanA ligase, Bacteria; D014640:Vancomycin; D019729:Carbon-Oxygen Ligases