Oral immunization with bacterial extracts for protection against acute bronchitis in elderly institutionalized patients with chronic bronchitis.

Acute bronchitis is a major source of morbidity in elderly patients. The purpose of this study was to assess the preventive effects of oral immunisation with a bacterial extract. Three hundred and fifty four patients with chronic bronchitis, living in institutions for the elderly (aged > 65 yrs), were included in a randomized, placebo-controlled, double-blind study. The purpose of the study was to assess preventive effects of OM-85 BV (an immunostimulating agent consisting of lyophilized fractions of eight of the most common pathogens isolated in respiratory tract infections) against acute lower respiratory tract infections. Two hundred and ninety patients completed the study (143 taking placebo and 147 taking OM-85 BV). There was a 28% reduction in the number of lower respiratory tract infections in the patients treated with OM-85 BV; this was entirely due to 40% reduction in the number of episodes of acute bronchitis (p < 0.01), with no difference in the number of episodes of pneumonia and bronchopneumonia. A larger number of patients in the OM-85 BV group were free of acute bronchitis throughout the 6 month study period (96 vs 69) and there was a 28% reduction in the number of antibiotic prescriptions in the OM-85 BV treated group. These results suggest that OM-85 BV has a protective effect against acute bronchitis in elderly patients living in institutions.