Risk factors for nasopharyngeal carriage of Streptococcus pneumoniae and effects of a hygiene intervention: repeated cross-sectional cohort study at day care centres.

Background: Day care attendance and antibiotic consumption are major risk factors for carriage of antibiotic-susceptible and non-susceptible pneumococci. We describe the nasopharyngeal carriage of antibiotic-susceptible and non-susceptible pneumococci among children at day care centres (DCCs), analyse the association of potential risk factors with carriage, and examine the effects of a hygiene intervention on carriage.

Methods: Thirty DCCs in 2 communities were included in a cohort intervention trial. Nasopharyngeal cultures and information on the children were obtained every 6 months. The study lasted 2.5 y and the hygiene intervention was introduced at half of the DCCs during the last 1.5 y of the study. The results were analysed using a mixed effects logistic regression model.

Results: A total of 5663 cultures were obtained from 2399 children, of which 55.6% grew pneumococci. Of the pneumococci, 27.9% were penicillin-non-susceptible (PNSP). The hygiene intervention was associated with a decreased risk of pneumococcal carriage, but this did not reach statistical significance for PNSP carriage. Pneumococcal and PNSP carriage was negatively associated with age, varied significantly between DCCs, and was positively associated with the number of preceding colds. Individual antibiotic use (mainly penicillin/amoxicillin) at the time of sampling and/or during the preceding month was associated with a decreased risk of pneumococcal and PNSP carriage. Individual use of cephalosporins was associated with an increased risk of carriage of penicillin and TMP-SMX-non-susceptible pneumococci.

Conclusion: The hygiene intervention at the DCCs reduced the risk of pneumococcal carriage and the individual use of antibiotics was found to affect carriage in a complex manner.