Objective: To assess the prevalence of and factors associated with smoking experimentation among adolescents. Methods: Cross-sectional study, using a specific questionnaire to interview 2,883 students from 7th to 10th grade in schools located in the urban area of the city of Cuiabá, in the state of Mato Grosso, Brazil. Prevalence was estimated, and the principal factors related to cigarette experimentation were analyzed. Subsequently, a hierarchical logistic model was used to describe the chances of cigarette experimentation related to the variables being investigated. Results: The prevalence of cigarette experimentation was 30.2%. In the final model of the analysis, the main variables related to cigarette experimentation were low maternal level of education (OR = 2.44; 95% CI: 1.72-3.47); low socioeconomic level (OR = 1.39; 95% CI: 1.01-1.93); studying in a public school (OR = 1.56; 95% CI: 1.22-2.00); being in 10th grade (OR = 3.45; 95% CI: 2.63-4.54); attending school in the evening (OR = 2.44; 95% CI: 1.85-3.22); having divorced parents (OR = 1.23; 95% CI: 1.02-1.49); having been held back for one school year (OR = 2.17; 95% CI: 1.78-2.70); having friends who smoke (OR = 3.75; 95% CI: 2.99-4.70) having a sibling who smokes (OR = 2.44; 95% CI: 1.82-3.27); and being older (age 17-19 years) (OR = 2.44; 95% CI: 1.39-4.17). Conclusions: A high proportion of adolescents have experimented with smoking. After adjusting for confounding variables, the factors most strongly associated with cigarette experimentation were maternal level of education, age of the adolescent, attending school in the evening, having been held back for one school year and having a sibling who smokes. Preventive measures must be directed at adolescents in schools in order to control smoking.

Keywords: Smoking; Adolescent; Students; Risk factors.

Objective: To determine the prevalence and the characteristics of Mycoplasma pneumoniae-related community-acquired pneumonia (CAP) and parapneumonic pleural effusion (PPE) in children and adolescents. Methods: This was a retrospective observational study involving 121 patients with CAP/PPE hospitalized in a tertiary referral hospital between 2000 and 2008, divided into six groups according to the etiologic agent (G1 to G6, respectively): M. pneumoniae with or without co-infection, in 44 patients (group 1); etiologic agents other than M. pneumoniae, in 77 (group 2); M. pneumoniae without co-infection, in 34 (group 3); Streptococcus pneumoniae, in 36 (group 4); Staphylococcus aureus, in 31 (group 5); and M. pneumoniae/S. pneumoniae co-infection, in 9 (group 6). Results: In comparison with group 2, group 1 showed higher frequencies of females, dry cough, and previous use of beta-lactam antibiotics; longer duration of symptoms prior to admission; and lower frequencies of use of mechanical ventilation and chest tube drainage. In comparison with groups 4 and 5, group 3 showed higher frequencies of previous use of beta-lactam antibiotics and dry cough; longer duration of symptoms prior to admission; a lower frequency of use of chest tube drainage; a higher mean age and a lower frequency of nausea/vomiting (versus group 4 only); and a lower frequency of use of mechanical ventilation (versus group 5 only). M. pneumoniae/S. pneumoniae co-infection increased the duration of symptoms prior to admission. Conclusions: In this sample, the prevalence of M. pneumoniae-related CAP/PPE was 12.75%. Although the disease was milder than that caused by other microorganisms, its course was longer. Our data suggest that M. pneumoniae-related CAP/PPE in children and adolescents should be more thoroughly investigated in Brazil.

Keywords: Pleural effusion; Empyema, pleural; Pneumonia; Mycoplasma pneumoniae.