Population-based active surveillance for neonatal group B streptococcal infections in Alberta, Canada: implications for vaccine formulation.
BACKGROUND
Knowledge of circulating serotypes of group B Streptococcus (GBS) is important for formulation of vaccines. There are no Canadian data on the serotype distribution of neonatal GBS isolates.


METHODS
Using a retrospective laboratory and health record survey between 1993 and 1994 (before introduction of Canadian prevention guidelines) and prospective active laboratory-based surveillance from 1995 to 1999 of all laboratories in Alberta, we identified 168 cases of invasive neonatal GBS infections including stillbirths among 262,398 total births; 118 of 123 (96%) isolates from 1995 to 1999 were serotyped, and the corresponding neonatal health records were reviewed.


RESULTS
The average annual incidence was 0.64 of 1000 total births/year. Of these 95 (57%) had early onset disease (EOD), 15 (9%) were still births and 58 (34%) had late onset disease (LOD). Eighty-one percent of EOD cases were caused by serotypes Ia, Ia/c, Ia/c/R, III, III/R and V, V/R, whereas 81% of LOD cases were caused by serotypes III and III/R. GBS serotypes containing the C protein along with serotypes III and V as a group constituted 91% (107 of 118) of all GBS cases in our population. The most common clinical presentation was bacteremia without focus (74%) followed by meningitis (14%) and pneumonia (12%). During 1995 to 1999, in addition to 13 stillbirths, there were 6 of 64 (9%) neonatal deaths among EOD cases and 1 of 46 (2%) neonatal death among LOD cases.


CONCLUSIONS
In this population-based study stillbirths account for a proportion of cases that are not routinely counted and represent a group for which intrapartum antibiotics would likely not be effective, but potentially preventable by vaccination. Inclusion of serotypes Ia, III and V in a conjugate vaccine or serotypes III and V conjugated with the C protein in a GBS vaccine could theoretically provide protection against the majority of GBS invasive disease in Alberta neonates.
Davies
H D
HD
Departments of Microbiology and Infectious Disease, Pediatrics, and Community Health, Child Health Research Unit, Alberta Children's Hospital, University of Calgary, Calgary, Alberta, Canada. dele.davies@crha-health.ab.ca
Raj
S
S
Adair
C
C
Robinson
J
J
McGeer
A
A
D000416:Alberta / Q000453:epidemiology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D016012:Poisson Distribution; D011159:Population Surveillance; D012189:Retrospective Studies; D012307:Risk Factors; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000517:prevention & control*; D022541:Streptococcal Vaccines / Q000008:administration & dosage*; D013292:Streptococcus agalactiae / Q000302:isolation & purification*; D014611:Vaccination / Q000592:standards* / Q000639:trends
D022541:Streptococcal Vaccines