Chlamydia pneumoniae serological status is not associated with asthma in children or young adults

Background The factors that cause the allergic sensitization and inflammati on in asthma still remain to be clarified. A role for Chlamydia pneumoniae has been suggested although serological studies have produced conflicting f indings. This study aims to clarify the relationship between asthmatic vari ables and C. pneumoniae serological status. Methods A case-control study was undertaken on an asthma-enriched subset fr om a longitudinal birth cohort. Ln all, 198 subjects (96 with self-reported asthma) had C. pneumoniae serology (microimmunofluorescence [MIF] IgG, IgA ) undertaken at age 11 and age 21 and assessment made in relation to a numb er of asthma variables. Results The only statistically significant finding was in subjects self-rep orting asthma at age 21 who had evidence of lower Ige titres (P = 0.046), a finding in the opposite direction to that expected from the hypothesis. Su bjects with high Ige titres (greater than or equal to 128) were less likely to have reported ever having asthma; odds ratio (OR) = 0.29, (95% CI: 0.10 -0.87). No association existed between symptoms suggestive of asthma in the previous 12 months and either IgG (P = 0.127) or IgA (P = 0.189) antibody titres at age 21. Likewise, no association was found between symptoms sugge stive of asthma in the previous two years and C. pneumoniae IgG antibody ti tre (P = 0.81) at age 11. There was no evidence of an association with any of the other variables examined at either age 11 or age 21. These included use of inhaled steroids, serum IgE levels, airway responsiveness, skin test evidence of atopy, or smoking status. Conclusion The results of this study suggest that C. pneumoniae infection w hen diagnosed by MIF serology is not a major risk factor for the developmen t of asthma in children and young adults. The study has not, however, addre ssed the role this organism may play in specific asthmatic subsets or asthm a exacerbations.