Background: Respiratory tract infections are common and remain a major source of morbidity, mortality and economic cost worldwide, despite advances in modern medicine. One treatment approach is to non-specifically increase the immune response or augment innate defense mechanisms through the use of bacterial lysates. Polyvalent Mechanical Bacterial Lysate (PMBL) is a bacterial lysate made from a wide range of pathogenic bacteria, including all of the most commonly occurring pathogens of the upper and lower respiratory tract obtained by mechanical lysis.
Aim: To test the available evidence that PMBL is able to prevent respiratory tract infections.
Methods: A number of studies investigating randomized comparisons of PMBL (active) with placebo or no treatment (control) were selected for analysis. The primary outcome measure was the prevention of exacerbations or acute respiratory tract infection. The results were expressed as relative risk (RR) and the number of patients needed to treat for one to benefit (NNTB).
Results: Data from 2557 patients from 15 randomized clinical trials (RCTs) was investigated. PMBL induced a significant reduction of infections vs placebo (RR -0.513; 95% CI; -0.722 - -0.303; p = 0.00). The NNTB was 1.15. The RR was always in favor of PMBL (in recurrent respiratory infections other than COPD, chronic bronchitis and tuberculosis, RR -0.502; 95% CI -0.824 - -0.181; in children RR -2.204; 95% CI -3.260 - -1.147; in COPD or chronic bronchitis, RR -0.404; 95% CI -0.864-0.057; in tuberculosis, RR -0.502; 95% CI -0.890 - -0.114).
Conclusions: The results of the present meta-analysis suggest that PBML is effective in both in children and in adults in preventing respiratory tract infections. Our current meta-analysis shows that there is a trend with PBML toward clinically significant results in patients with COPD but it did not quite achieve statistical significance due to the small number of COPD studies.
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