title: Serratia marcescens in a neonatal intensive care unit: two long-term multiclone outbreaks in a 10-year observational study.
abstract: We investigated two consecutive Serratia marcescens (S. marcescens) outbreaks which occurred in a neonatal intensive care unit (NICU) of a tertiary level hospital in North Italy in a period of 10 years (January 2003-December 2012). Risk factors associated with S. marcescens acquisition were evaluated by a retrospective case-control study. A total of 21,011 clinical samples was examined: S. marcescens occurred in 127 neonates: 43 developed infection and 3 died. Seven clusters were recorded due to 12 unrelated clones which persisted for years in the ward, although no environmental source was found. The main epidemic clone A sustaining the first cluster in 2003 reappeared in 2010 as an extended spectrum ?-lactamase (ESBL)-producing strain and supporting the second epidemic. Birth weight, gestational age, use of invasive devices and length of stay in the ward were significantly related to S. marcescens acquisition. The opening of a new ward for non-intensive care-requiring neonates, strict adherence to alcoholic hand disinfection, the timely identification and isolation of infected and colonized neonates assisted in containing the epidemics. Genotyping was effective in tracing the evolution and dynamics of the clones demonstrating their long-term persistence in the ward.
authors.affiliation: Department to Integrated Activity of Laboratory Medicine, Modena, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Casolari
authors.forename: Monica
authors.initials: M
authors.lastname: Pecorari
authors.forename: Elisa
authors.initials: E
authors.lastname: Della Casa
authors.forename: Silvia
authors.initials: S
authors.lastname: Cattani
authors.forename: Claudia
authors.initials: C
authors.lastname: Venturelli
authors.forename: Giuliana
authors.initials: G
authors.lastname: Fabio
authors.forename: Sara
authors.initials: S
authors.lastname: Tagliazucchi
authors.forename: Giulia Fregni
authors.initials: GF
authors.lastname: Serpini
authors.forename: Mario
authors.initials: M
authors.lastname: Migaldi
authors.forename: Patrizia
authors.initials: P
authors.lastname: Marchegiano
authors.forename: Fabio
authors.initials: F
authors.lastname: Rumpianesi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Ferrari
mesh_terms: D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D007558:Italy; D008297:Male; D012189:Retrospective Studies; D016868:Serratia Infections / Q000453:epidemiology* / Q000382:microbiology; D012706:Serratia marcescens / Q000235:genetics / Q000302:isolation & purification*