4. Statistical AnalysisData processing and analysis were performed using StatSoft, Inc. STATISTICA 10. The potential predictor variables were tested in separate univariate analyses (Chi-squared or the Fisher exact test, as appropriate) for their association with upper respiratory colonization by S. pneumoniae in each etc season (autumn, winter, spring). Odds ratio (OR) and their 95% confidence intervals (CI) were calculated. Statistical significance was set at P < 0.05. Significant univariate predictors (P < 0.1) were tested for inclusion in the multivariate models. A model including all such predictors was constructed for each season, and nonsignificant variables were removed sequentially until only those significant at P < 0.1 remained.

Variables of particular interest based on previous studies, such as children age, recent RTIs, and antibiotic use, were included even when were not statistically significant. Results of logistic regression analysis are reported as adjusted odds ratio (OR) with 95% CI. Statistical significance was set at P < 0.05.3. Results3.1. Upper Respiratory Colonization by S. pneumoniae and the Affecting FactorsDuring the study period, from November 2002 to June 2003, 933 nasopharyngeal samples were obtained in three seasons. A total of 311 children aged 3 to 5 were included in this study: 241 children attending four DCCs and 70 children staying at home. Demographic data of the studied children are given in Table 1. Of 356 positive pneumococcal cultures, 128 (36%) isolates were obtained from throat, 121 (34%) from nostrils, and 107 (30%) isolates colonized both throat and nostrils.

S. pneumoniae (SP) was isolated from 115 (37%), 103 (33.1%), and 138 (44.4%) children in autumn, winter, and spring, respectively. Spring, as compared to winter, was a statistically significant factor associated with upper respiratory colonization by S. pneumoniae (P = 0.0051, OR 1.6, 95% CI 1.2�C2.2). The average carriage rate among children attending DDCs was 41.9%, 40.2%, and 48.1% in autumn, winter, and spring, respectively. In contrast, the carriage rate among children staying at home was 20%, 24.3%, and 31,4% in these seasons, respectively.Table 1Demographic data of studied children.Multivariate analysis determined DCC attendance as strongly related to SP colonization in all three seasons, but important seasonal differences in SP colonization were demonstrated (Table 2).

DCC attendance and type of antibiotic used were independent predictors of SP colonization in autumn. Univariate analysis showed that, in this season, antibiotic consumption increased the likelihood of S. pneumoniae isolation (P = 0.04, OR 1.6, 95% CI 1.0�C2.6), demonstrating Anacetrapib significantly higher pneumococcal colonization among children after two antibiotic courses (P = 0.007, OR 1.8, 95% CI 1.3�C2.7), and also among children who underwent treatment by ��-lactam plus macrolide (P = 0.02, OR 2.