Prevalence and risk factors for nasopharyngeal carriage of Streptococcus pneumoniae among adolescents De ´ a M. Cardozo, 1 Cristiana M. Nascimento-Carvalho, 1 Ana-Lu ´ cia S. S. Andrade, 2 Annı ´bal M. Silvany-Neto, 3 Carla H. C. Daltro, 4 Maria-Ange ´ lica S. Branda ˜o, 5 Angela P. Branda ˜o 6 and Maria-Cristina C. Brandileone 6 Correspondence Cristiana M. Nascimento-Carvalho nascimentocarvalho@hotmail.com 1 Department of Paediatrics, School of Medicine, Federal University of Bahia, Avenida Reitor Miguel Calmon, s/n, CEP 40110-100, Salvador, Bahia, Brazil 2 Institute of Tropical Pathology and Public Health, Federal University of Goia ´ s, Goia ˆ nia, Goia ´ s, Brazil 3 Department of Preventive Medicine, School of Medicine, Federal University of Bahia, Salvador, Bahia, Brazil 4 Bahiana School of Medicine and Public Health, Salvador, Bahia, Brazil 5 Central Laboratory of Bahia (LACEN), Salvador, Bahia, Brazil 6 Bacteriology Branch, Adolfo Lutz Institute (IAL), Sa ˜ o Paulo, Brazil Received 27 June 2007 Accepted 30 September 2007 Data on the prevalence of pneumooccal nasopharyngeal carriage and its risk factors among adolescents are scarce. The aim of this study was to provide such information. A cross-sectional, population-based prospective study was conducted. Participants were 1013 adolescents (age range 10–19 years) randomly recruited in 22 public schools. Those schools were randomly chosen among 307 public schools from 11 Sanitary Districts of Salvador, Brazil. Nasopharyngeal samples were assessed by standard procedures to recover and identify Streptococcus pneumoniae. Data on potential risk factors were gathered by confidential interview based on a standardized questionnaire. Pneumococci were recovered from 8.2 % [83/1013, 95 % confidence interval (CI) 6.6–10.0]. By stepwise logistic regression, pneumococcal colonization was independently associated with younger age [odds ratio (OR) 0.85, 95 % CI 0.77–0.94, P50.001], being male (OR 1.78, 95 % CI 1.11–2.85, P50.02), exposure to passive smoke in the household (OR 1.76, 95 % CI 1.10–2.79, P50.02), having an upper respiratory infection during recruitment (OR 2.67, 95 % CI 1.67–4.28, P,0.001) and having a history involving an episode of acute asthma during the last year (OR 2.89, 95 % CI 1.18–7.08, P50.03). The estimated probability of pneumococcal colonization decreased with age (x 2 for trend58.52, P50.003). These findings provide tools for increasing the use of prevention strategies for pneumococcal diseases, such as pneumococcal vaccination among asthmatic patients and public health measures to stop smoking. INTRODUCTION The incidence of invasive pneumococcal disease is highest among children and the elderly (CDC, 1997). However, respiratory infections are an important cause of morbidity and mortality among adolescents (Benguigui, 1992). Among children, Streptococcus pneumoniae is a major causative agent of such infections (Heiskanen-Kosma et al., 1998). The nasopharynx is known to be the main ecological reservoir of S. pneumoniae, from where it can give rise to disease after extending to other areas of the respiratory tract or penetrating normally sterile body fluids (Austrian, 1986). Although nasopharyngeal isolates are not useful for predicting the causative agent of invasive disease in individuals, they reflect epidemiological aspects of pneu- mococcal disease in the community (Brueggemann et al., 2003). Studies conducted over the last decades have gradually revealed the connection between pneumococcal carriage, and mucosal and invasive infections caused by the Abbreviations: CDC, Centers for Disease Control and Prevention; CI, confidence interval; OR, odds ratio. Journal of Medical Microbiology (2008), 57, 185–189 DOI 10.1099/jmm.0.47470-0 47470 G 2008 SGM Printed in Great Britain 185