Serotype Distribution And Invasive Potential Of Group B

Serotype Distribution and Invasive Potential of Group B
Streptococcus Isolates Causing Disease in Infants and
Colonizing Maternal-Newborn Dyads
Mashudu Madzivhandila1, Peter V. Adrian1, Clare L. Cutland1, Locadiah Kuwanda1, Stephanie J. Schrag2,
Shabir A. Madhi1*
1 Vaccine Preventable Diseases and Respiratory and Meningeal Pathogens Research Unit, Department of Science andTechnology/National Research Foundation,
University of Witwatersrand, Johannesburg, South Africa, 2 Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America

Abstract
Background: Serotype-specific polysaccharide based group B streptococcus (GBS) vaccines are being developed. An
understanding of the serotype epidemiology associated with maternal colonization and invasive disease ininfants is
necessary to determine the potential coverage of serotype-specific GBS vaccines.
Methods: Colonizing GBS isolates were identified by vaginal swabbing of mothers during active labor and from skin of their
newborns post-delivery. Invasive GBS isolates from infants were identified through laboratory-based surveillance. GBS
serotyping was done by latex agglutination. Serologicallynon-typeable isolates were typed by a serotype-specific PCR
method. The invasive potential of GBS serotypes associated with sepsis within seven days of birth was evaluated in
association to maternal colonizing serotypes.
Results: GBS was identified in 289 (52.4%) newborns born to 551 women with GBS-vaginal colonization and from 113 (5.6%)
newborns born to 2,010 mothers in whom GBS was not culturedfrom vaginal swabs. The serotype distribution among vaginalcolonizing isolates was as follows: III (37.3%), Ia (30.1%), and II (11.3%), V (10.2%), Ib (6.7%) and IV (3.7%). There were no significant
differences in serotype distribution between vaginal and newborn colonizing isolates (P = 0.77). Serotype distribution of invasive
GBS isolates were significantly different to that of colonizingisolates (P,0.0001). Serotype III was the most common invasive
serotype in newborns less than 7 days (57.7%) and in infants 7 to 90 days of age (84.3%; P,0.001). Relative to serotype III, other
serotypes showed reduced invasive potential: Ia (0.49; 95%CI 0.31–0.77), II (0.30; 95%CI 0.13–0.67) and V (0.38; 95%CI 0.17–0.83).
Conclusion: In South Africa, an anti-GBS vaccine including serotypes Ia, Iband III has the potential of preventing 74.1%,
85.4% and 98.2% of GBS associated with maternal vaginal-colonization, invasive disease in neonates less than 7 days and
invasive disease in infants between 7–90 days of age, respectively.
Citation: Madzivhandila M, Adrian PV, Cutland CL, Kuwanda L, Schrag SJ, et al. (2011) Serotype Distribution and Invasive Potential of Group B StreptococcusIsolates Causing Disease in Infants and Colonizing Maternal-Newborn Dyads. PLoS ONE 6(3): e17861. doi:10.1371/journal.pone.0017861
Editor: Adam Ratner, Columbia University, United States of America
Received January 6, 2011; Accepted February 9, 2011; Published March 21, 2011
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, builtupon, or otherwise used by anyone for
any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: This work is based upon research supported by the South African Research Chairs Initiative of the Department of Science and Technology and National
Research Foundation (Vaccine Preventable Diseases Research Chair Grant). The funders had no rolein study design, data collection and analysis, decision to
publish, or preparation of the manuscript.
Competing Interests: S.A.M. is currently receiving research-grant support from Novartis in relation to GBS. All other authors declare that no competing interests
exist.
* E-mail: madhis@rmpru.co.za

associated sepsis during early infancy [6,7]. The success of
maternal immunization in...