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Molecular Epidemiology of an Outbreak of Serratia marcescens in a Neonatal Intensive Care Unit

Published online by Cambridge University Press:  02 January 2015

Paolo Villari*
Affiliation:
Department of Experimental Medicine and Pathology, University “La Sapienza, ”Rome, Italy
Margherita Crispino
Affiliation:
Departments of Health and Preventive Sciences, University “Federico II, ” Naples, Italy
Alessandra Salvadori
Affiliation:
Departments of Health and Preventive Sciences, University “Federico II, ” Naples, Italy
Alda Scarcella
Affiliation:
Pediatrics, University “Federico II, ” Naples, Italy
*
Department of Experimental Medicine and Pathology, University “La Sapienza, ” Viale Regina Elena 324, 00161 Rome, Italy

Abstract

Objective:

To investigate and control a biphasic outbreak of Serratia marcescens in a neonatal intensive care unit (NICU).

Design:

Epidemiological and laboratory investigation of the outbreak.

Setting:

The NICU of the 1,470-bed teaching hospital of the University “Federico II,” Naples, Italy.

Patients:

The outbreak involved 56 cases of colonization by S marcescens over a 15-month period, with two epidemic peaks of 6 and 3 months, respectively. Fourteen (25%) of the 56 colonized infants developed clinical infections, 50% of which were major (sepsis, meningitis, or pneumonia).

Methods:

Epidemiological and microbiological investigations, analysis of macrorestriction pattern of genomic DNA through pulsed-field gel electrophoresis (PFGE) of clinical and environmental isolates, and institution of infection control measures.

Results:

Analysis of macrorestriction patterns of genomic DNA by PFGE demonstrated that the vast majority of S marcescens isolates, including three environmental strains isolated from two handwashing disinfectants and the hands of a nurse, were of the same clonal type. The successful control of the outbreak was achieved through cohorting of noncolonized infants, isolation of S marcescens-infected and -colonized infants, and an intense educational program that emphasized the need for adherence to glove use and handwashing policies. The NICU remained open to new admissions.

Conclusions:

Outbreaks caused by S marcescens are very difficult to eradicate. An infection control program that includes molecular typing of microorganisms and the proper dissemination among staff members of the typing results is likely to be very effective in reducing NICU-acquired infections and in controlling outbreaks caused by S marcescens, as well as other multiresistant bacteria.

Information

Type
Original Articles
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2001

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