Outbreak of late-onset group B Streptococcus in a neonatal intensive care unit.
BACKGROUND
In September 2007, the Tennessee Department of Health was notified of a cluster of late-onset group B streptococcal (GBS) infections in a neonatal intensive care unit (NICU). Outbreaks of late-onset GBS are rare.


METHODS
A case was defined as culture-confirmed invasive GBS infection in a neonate aged > or =7 days, identified in hospital A during August 23 to September 6, 2007. We reviewed medical records; examined NICU microbiology reports; and performed serotyping, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) on invasive isolates. Maternal GBS screening, prophylaxis, and infection control policies were reviewed and staff practices observed.


RESULTS
Five cases of late-onset GBS were identified. None of the mothers of the infants received optimal GBS prophylaxis. Patient isolates were of 2 serotypes, 3 PFGE patterns, and 2 MLST patterns. Three isolates were indistinguishable on subtyping. These 3 cases were clustered in time. No common health care providers were identified. Infection control deviations in the NICU were observed.


CONCLUSIONS
We identified a multiclonal cluster of 5 late-onset GBS cases. Multiple factors likely contributed to the outbreak, including nosocomial transmission of GBS. Further efforts to prevent late-onset GBS disease are necessary.
MacFarquhar
Jennifer K
JK
Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA, USA. jmacfarquhar@hotmail.com
Jones
Timothy F
TF
Woron
Amy M
AM
Kainer
Marion A
MA
Whitney
Cynthia G
CG
Beall
Bernard
B
Schrag
Stephanie J
SJ
Schaffner
William
W
D015373:Bacterial Typing Techniques; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D016172:DNA Fingerprinting; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D013714:Tennessee / Q000453:epidemiology