Background: Serotype 3 is known for its ability to cause invasive diseases worldwide. In the United States, after introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), the prevalence of a serotype 3 clone (Netherlands3-31/ST180) increased. The present study was aimed to evaluate the importance of serotype 3 clones in noninvasive infections in Israel, Costa Rica, and Lithuania.
Methods: Molecular typing and antibiotic resistance were performed on 77 serotype 3 strains recovered from pediatric noninvasive infections during 2003–2005, and on 50 carried strains from healthy carriers.
Results: Serotype 3 ranked second among isolates from noninvasive infections in Costa Rica and Lithuania, and seventh among the Israeli isolates. Pulsed field gel electrophoresis (PFGE) analysis revealed the presence of 1 major cluster (64/77, 83%); this cluster comprised 60/64 fully susceptible strains that corresponded to the Netherlands3-31/ST180 clone, and 4/64 multidrug-resistant strains, all from Lithuania, that corresponded to ST505, a double locus variant of ST180. Two additional fully susceptible clones, ST458 (11/77, 14%) and ST1116 (2/77, 3%), were found among the Israeli and Costa Rican strains, respectively. The same PFGE clusters identified among noninvasive infections were found among 50 isolates from carriers, with the same molecular characteristics.
Conclusions: Serotype 3 accounts for a large proportion of mucosal disease in children, even before the introduction of PCV7. The data presented here describe for the first time the importance of a multidrug-resistant serotype 3 clone, ST505, in noninvasive infections.
From the *Pediatric Infectious Disease Unit, Soroka University Medical Center and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; †Instituto de Atención Pediátrica and Universidad de Ceincias Medicas, San José, Costa Rica; and ‡Kaunas 2nd Clinical Hospital, Lithuania.
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Accepted for publication February 21, 2008.
This work was partially supported by Wyeth (a grant to the Instituto de Atención Pediátrica and to the Pediatric Infectious Disease Unit, Soroka University Medical Center), and by GlaxoSmithKline (a grant to the Pediatric Infectious Disease Unit, Soroka University Medical Center).
Wyeth and GlaxoSmithKline had no role in the design, conduct, and analysis of the study.
Address for correspondence: Nurith Porat, PhD, Pediatric Infectious Disease Unit, Soroka University Medical Center, P.O. Box 151, Beer Sheva 84101, Israel. E-mail: firstname.lastname@example.org.