Abstract
Respiratory tract infections (RTIs) are a leading cause of morbidity and also represent a cause of death in some parts of the world. The treatment of RTIs implies a continuous search for stronger therapies and represents an economical burden for health services and society. In this context the prevention of infections is absolutely required. The use of bacterial lysates as immuno-modulators to boost immunological response is widely debated. Aim of this review is to summarize the main clinical studies on the effect of the bacterial lysate OM-85 in treating RTIs in susceptible subjects - namely children and chronic obstructive pulmonary disease (COPD)-affected adults. Results from clinical trials and recent systematic reviews are reported.The results show that mean number of RTIs decreases upon treatment with OM-85, as measured by frequency of exacerbations or number of antibiotic courses. Data from systematic reviews indicated that OM-85 is particularly beneficial in children at high risk of RTIs. In COPD-affected adults, clinical studies showed that treatment with OM-85 reduced exacerbations, although systematic reviews did not legitimate the protective effect of OM-85 toward COPD as significant.The use of OM-85 could be efficacious in reducing exacerbation frequency of RTIs in children and adults at risk. However further high-quality studies are needed to better explain the mechanism of action and confirm the beneficial results of OM85.