Trial of roxithromycin in subjects with asthma and serological evidence ofinfection with Chlamydia pneumoniae

An association has been reported between chronic infection with Chlamydia p neumoniae and the severity of asthma, and uncontrolled observations have su ggested that treatment with antibiotics active against C. pneumoniae leads to an improvement in asthma control. We studied the effect of roxithromycin in subjects with asthma and immunoglobulin G (IgG) antibodies to C. pneumo niae greater than or equal to 1:64 and/or IgA antibodies greater than or eq ual to 1:16. A total of 232 subjects, from Australia, New Zealand, Italy, o r Argentina, were randomized to 6 wk of treatment with roxithromycin 150 mg twice a day or placebo. At the end of 6 wk, the increase from baseline in evening peak expiratory flow (PEF) was 15 L/min with roxithromycin and 3 L/ min with placebo (p = 0.02). With morning PEF, the increase was 14 L/min wi th roxithromycin and 8 L/min with placebo (NS). In the Australasian populat ion, the increase in morning PEP was 18 L/min and 4 L/min, respectively (p = 0.04). At 3 mo and 6 mo after the end of treatment, differences between t he two groups were smaller and not significant. Six weeks of treatment with roxithromycin led to improvements in asthma control but the benefit was no t sustained. Further studies are necessary to determine whether the lack of sustained benefit is due to failure to eradicate C. pneumoniae.