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Journal of Clinical Microbiology, October 2007, p. 3224-3229, Vol. 45, No. 10
0095-1137/07/$08.00+0     doi:10.1128/JCM.01182-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Analysis of Group B Streptococcal Isolates from Infants and Pregnant Women in Portugal Revealing Two Lineages with Enhanced Invasiveness

E. R. Martins, M. A. Pessanha, M. Ramirez,^* J. Melo-Cristino, and the Portuguese Group for the Study of Streptococcal Infections

Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal

Received 12 June 2007/ Returned for modification 18 July 2007/ Accepted 2 August 2007

The populations of group B streptococcus (GBS) associated with vaginal carriage in pregnant women and invasive neonatal infections in Portugal were compared. GBS isolates were characterized by serotyping, pulsed-field gel electrophoresis (PFGE) profiling, and multilocus sequence typing (MLST). Serotypes III and V accounted for 44% of all colonization isolates (n = 269), whereas serotypes III and Ia amounted to 69% of all invasive isolates (n = 64). Whereas serotype Ia was associated with early-onset disease (EOD), serotype III was associated with late-onset disease (LOD). Characterization by PFGE and MLST identified very diverse populations in carriage and invasive disease. Serotype Ia was represented mainly by a single PFGE cluster defined by sequence type 23 (ST23) and the infrequent ST24. In contrast, serotype III was found in a large number of PFGE clusters and STs, but a single PFGE cluster defined by ST17 was found to be associated with invasive disease. Although serotype III was associated only with LOD, ST17 showed an enhanced capacity to cause both EOD and LOD. Our data reinforce the evidence for enhanced invasiveness of ST17 and identify a lineage expressing serotype Ia capsule and represented by ST23 and ST24 as having enhanced potential to cause EOD.

Published ahead of print on 15 August 2007.

E.R.M. and M.A.P. contributed equally to this work.

This article has been cited by other articles:

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