title: Molecular epidemiology of multidrug-resistant Acinetobacter baumannii in a tertiary care hospital in Naples, Italy, shows the emergence of a novel epidemic clone.
abstract: The molecular epidemiology of multidrug-resistant Acinetobacter baumannii was investigated in two intensive care units of the V. Monaldi university hospital in Naples, Italy, from May 2006 to December 2007. Genotype analysis by pulsed-field gel electrophoresis (PFGE), trilocus sequence-based typing (3LST), and multilocus sequence typing (MLST) of A. baumannii isolates from 71 patients identified two distinct genotypes, one assigned to PFGE group A, 3LST group 1, and ST2 in 14 patients and the other to PFGE group B, 3LST group 6, and ST78 in 71 patients, that we named ST2/A and ST78/B, respectively. Of these, ST2/A corresponded to European clone II identified in the same hospital during 2003 and 2004; ST78/B was a novel genotype that was isolated for the first time in May 2006 but became prevalent during 2007. The ST78/B profile was also identified in five patients from two additional hospitals in Naples during 2007. The ST2/A and ST78/B isolates were resistant to all antimicrobials tested, including carbapenems, but were susceptible to colistin. Both ST2/A and ST78/B isolates possessed a plasmid-borne carbapenem-hydrolyzing oxacillinase gene, bla(OXA-58), flanked by ISAba2 and ISAba3 elements at the 5' and 3' ends, respectively. The selection of the novel ST78/B A. baumannii clone might have been favored by the acquisition of the bla(OXA-58) gene.
authors.affiliation: Dipartimento di Scienze Mediche Preventive, Università di Napoli Federico II, Naples, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Giannouli
authors.forename: Susanna
authors.initials: S
authors.lastname: Cuccurullo
authors.forename: Valeria
authors.initials: V
authors.lastname: Crivaro
authors.forename: Anna
authors.initials: A
authors.lastname: Di Popolo
authors.forename: Mariano
authors.initials: M
authors.lastname: Bernardo
authors.forename: Federica
authors.initials: F
authors.lastname: Tomasone
authors.forename: Gerardino
authors.initials: G
authors.lastname: Amato
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brisse
authors.forename: Maria
authors.initials: M
authors.lastname: Triassi
authors.forename: Riccardo
authors.initials: R
authors.lastname: Utili
authors.forename: Raffaele
authors.initials: R
authors.lastname: Zarrilli
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D016172:DNA Fingerprinting; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007362:Intensive Care Units; D007558:Italy / Q000453:epidemiology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D001618:beta-Lactamases; C108449:oxacillinase