[Bacterial lysates: history and availability]

The use of bacterial lysates (BLs) can be traced back to the end of the nineteenth century, and they are currently available in several countries across all continents. Over the last few decades, BLs have been used, both in pediatric patients and in adults, mainly for the prevention and treatment of bacterial infections of the respiratory tract. BLs are produced from bacterial cultures that undergo cell lysis with two different methods: mechanical lysis and chemical lysis. The in vivo mechanism of action is still not fully understood, and the main hypotheses focus on mucosal immunity modulation. We searched PubMed for relevant papers on the use of BLs for the prevention and treatment of chronic obstructive pulmonary disease and recurrent respiratory infections both in adult and in pediatric patients. We retrieved 169 articles and after screening and selection, we analyzed 13 RCTs focusing on adult patients and 8 on pediatric patients. The outcomes assessed were mainly about the efficacy of BLs on exacerbations, hospitalizations, antibiotic treatment, fever, number of episodes and days of absence from work or school. Many aspects of BLs are still not well understood and the quality of available studies is not satisfactory; in order to place BLs within the scope of Public Health, further good quality studies are needed, keeping in mind the necessity to respond to the needs of patients for whom no alternative effective treatments are available.