title: Polyvalent mechanical bacterial lysate for the prevention of recurrent respiratory infections: a meta-analysis.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Internal Medicine, Unit of Respiratory Clinical Pharmacology, University of Rome Tor Vergata, Rome, Italy. mario.cazzola@uniroma2.it
authors.forename: Mario
authors.initials: M
authors.lastname: Cazzola
authors.forename: Sreedhar
authors.initials: S
authors.lastname: Anapurapu
authors.forename: Clive P
authors.initials: CP
authors.lastname: Page
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000737:chemistry*; D001428:Bacterial Vaccines / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012141:Respiratory Tract Infections / Q000517:prevention & control*; D018570:Risk Assessment; D018401:Sample Size; D055502:Secondary Prevention; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001428:Bacterial Vaccines