Molecular epidemiology of Serratia marcescens outbreaks in two neonatal intensive care units.
OBJECTIVE
Serratia marcescens can cause serious infections in patients in neonatal intensive care units (NICUs), including sepsis, pneumonia, urinary tract infection, and conjunctivitis. We report the utility of genetic fingerprinting to identify, investigate, and control two distinct outbreaks of S. marcescens.


METHODS
An epidemiologic investigation was performed to control two clusters of S. marcescens infections and to determine possible routes of transmission. Molecular typing by pulsed-field gel electrophoresis determined the relatedness of S. marcescens strains recovered from neonates, the environment, and the hands of healthcare workers (HCWs).


METHODS
Two geographically distinct level III-IV NICUs (NICU A and NICU B) in two university-affiliated teaching hospitals in New York City.


RESULTS
In NICU A, one major clone, "F," was detected among isolates recovered from four neonates and the hands of one HCW. A second predominant clone, "A," was recovered from four sink drains and one rectal surveillance culture from an asymptomatic neonate. In NICU B, four neonates were infected with clone "D," and three sink drains harbored clone "H." The attributable mortality rate from bloodstream infections was 60% (3 of 5 infants). The antimicrobial susceptibilities of clone F strains varied for amikacin, cefepime, and piperacillin/tazobactam.


CONCLUSIONS
S. marcescens causes significant morbidity and mortality in preterm neonates. Cross-transmission via transient hand carriage of a HCW appeared to be the probable route of transmission in NICU A. Sinks did not harbor the outbreak strains. Antimicrobial susceptibility patterns did not prove to be an accurate predictor of strain relatedness for S. marcescens.
Department of Pediatrics, School of Nursing, Columbia University, New York, New York, USA.
Vladana
V
Milisavljevic
Fann
F
Wu
Elaine
E
Larson
David
D
Rubenstein
Barbara
B
Ross
Lewis M
LM
Drusin
Phyllis
P
Della-Latta
Lisa
L
Saiman
D003428:Cross Infection / Q000453:epidemiology* / Q000235:genetics* / Q000517:prevention & control; D016172:DNA Fingerprinting; D004196:Disease Outbreaks / Q000517:prevention & control*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D008826:Microbial Sensitivity Tests; D016868:Serratia Infections / Q000453:epidemiology* / Q000235:genetics* / Q000517:prevention & control; D012706:Serratia marcescens / Q000235:genetics*; D014481:United States / Q000453:epidemiology