title: Outbreak of a cluster with epidemic behavior due to Serratia marcescens after colistin administration in a hospital setting.
abstract: Serratia marcescens causes health care-associated infections with important morbidity and mortality. Particularly, outbreaks produced by multidrug-resistant isolates of this species, which is already naturally resistant to several antibiotics, including colistin, are usually described with high rates of fatal outcomes throughout the world. Thus, it is important to survey factors associated with increasing frequency and/or emergence of multidrug-resistant S. marcescens nosocomial infections. We report the investigation and control of an outbreak with 40% mortality due to multidrug-resistant S. marcescens infections that happened from November 2007 to April 2008 after treatment with colistin for Acinetobacter baumannii meningitis was started at hospital H1 in 2005. Since that year, the epidemiological pattern of frequently recovered species has changed, with an increase of S. marcescens and Proteus mirabilis infections in 2006 in concordance with a significant decrease of the numbers of P. aeruginosa and A. baumannii isolates. A single pulsed-field gel electrophoresis (PFGE) cluster of S. marcescens isolates was identified during the outbreak. When this cluster was compared with S. marcescens strains (n = 21) from 10 other hospitals (1997 to 2010), it was also identified in both sporadic and outbreak isolates circulating in 4 hospitals in Argentina. In132::ISCR1::blaCTX-M-2 was associated with the multidrug-resistant cluster with epidemic behavior when isolated from outbreaks. Standard infection control interventions interrupted transmission of this cluster even when treatment with colistin continued in several wards of hospital H1 until now. Optimizing use of colistin should be achieved simultaneously with improved infection control to prevent the emergence of species naturally resistant to colistin, such as S. marcescens and P. mirabilis.
authors.affiliation: Instituto de Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina.
authors.forename: Andrea Karina
authors.initials: AK
authors.lastname: Merkier
authors.forename: María Cecilia
authors.initials: MC
authors.lastname: Rodríguez
authors.forename: Ana
authors.initials: A
authors.lastname: Togneri
authors.forename: Silvina
authors.initials: S
authors.lastname: Brengi
authors.forename: Carolina
authors.initials: C
authors.lastname: Osuna
authors.forename: Mariana
authors.initials: M
authors.lastname: Pichel
authors.forename: Marcelo H
authors.initials: MH
authors.lastname: Cassini
authors.forename: Daniela
authors.initials: D
authors.lastname: Centrón
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy*; D040981:Acinetobacter baumannii / Q000302:isolation & purification; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001118:Argentina / Q000453:epidemiology; D003091:Colistin / Q000627:therapeutic use*; D003428:Cross Infection / Q000453:epidemiology* / Q000401:mortality; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006761:Hospitals; D006801:Humans; D008297:Male; D016920:Meningitis, Bacterial / Q000188:drug therapy*; D008875:Middle Aged; D017720:Molecular Epidemiology; D058889:Molecular Typing; D012189:Retrospective Studies; D016868:Serratia Infections / Q000453:epidemiology* / Q000401:mortality; D012706:Serratia marcescens / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D003091:Colistin