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Open Access Research article

Risk factors for serotype 19A carriage after introduction of 7-valent pneumococcal vaccination

Robert Cohen12*, Corinne Levy2, Eric Bonnet3, Franck Thollot4, Michel Boucherat2, Bernard Fritzell3, Véronique Derkx2, Edouard Bingen5 and Emmanuelle Varon6

Author Affiliations

1 Department of Microbiology, CHI Créteil 40 Avenue de Verdun, France

2 ACTIV, Association Clinique Thérapeutique Infantile du Val de Marne, 27 rue Inkermann F94100 Saint Maur des Fossés, France

3 23 av Doct Lannelongue 75014 PARIS, Laboratoire Pfizer, France

4 AFPA, Association Française de Pédiatrie Ambulatoire 4 rue Parmentier F54270 Essey les Nancy, France

5 Department of Microbiology, Université Denis-Diderot-Paris7, Robert Debré hospital (AP-HP), 48 Bd Sérurier 75019 Paris, France

6 National Reference Center for Pneumococci, AP-HP, HEGP 20, rue Leblanc, F75015 Paris, France

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BMC Infectious Diseases 2011, 11:95  doi:10.1186/1471-2334-11-95

Published: 18 April 2011

Abstract

Background

After the implementation of 7-valent pneumococcal conjugate vaccine (PCV7), in several countries, serotype 19A is now the serotype most frequently involved in pneumococcal diseases and carriage. To determine factors potentially related to 19A nasopharyngeal (NP) carriage we analyzed data from an ongoing prospective French national surveillance study of pneumococcal NP carriage in young children.

Methods

NP swabs were obtained from children aged 6 to 24 months, either during routine check-ups with normal findings, or when they presented with acute otitis media (AOM). The swabs were sent for analysis to the French National Reference Centre for Pneumococci. Factors influencing pneumococcal carriage and carriage of penicillin non-susceptible (PNSP), 19A and PNS-19A were investigated by multivariate logistic regression.

Results

From 2006 to 2009, 66 practitioners enrolled 3507 children (mean age 13.6 months), of whom, 98.3% of children had been vaccinated with PCV7 and 33.4% of children attended daycare centres (DCC). Serotype 19A was found in 10.4% of the overall population, 20.5% of S. pneumoniae carriers (n = 1780) and 40.8% of PNSP carriers (n = 799). Among 19A strains, 10.7% were penicillin-susceptible, 80% intermediate and 9.3% fully resistant. Logistic regression analysis showed that the main factors associated with PNSP carriage were AOM (OR = 3.09, 95% CI [2.39;3.98]), DCC (OR = 1.70, 95% CI [1.42;2.03]), and recent antibiotic use (OR = 1.24, 95% CI [1.05;1.47]. The main factors predictive of 19A carriage were recent antibiotic use (OR = 1.81, 95% CI [1.42;2.30]), AOM (OR = 1.67, 95% CI [1.11;2.49]), DCC (OR = 1.56, 95% CI [1.21;2.2] and young age, <12 months (OR = 1.51, 95% CI [1.16;1.97]).

Conclusion

In a population of children aged from 6 to 24 months with a high rate of PCV7 vaccination coverage, we found that antibiotic exposure, DCC attendance and AOM were linked to 19A carriage.