Bacterial interference for the prevention and treatment of infections.

Bacterial interference refers to the antagonism between bacterial species during the process of surface colonisation and acquisition of nutrients. The clinical evidence on the potential applications of microorganisms for the prevention and/or treatment of infections in the upper respiratory, urogenital and gastrointestinal tracts was reviewed through the PubMed and Scopus databases. Data regarding factors that may affect the human microflora, thus contributing to tissue colonisation from potential pathogens, were also retrieved. The clinical evidence for application of the interfering ability of non-virulent bacteria to prevent or treat infections has been rather limited, although promising for certain purposes. A number of relevant preliminary trials suggest that in the upper respiratory tract the rate of recurrence of otitis media or streptococcal pharyngotonsillitis appears to decrease using selected bacteria with inhibitory ability against common pathogens of upper respiratory tract in combination with appropriate antibiotic treatment. Regarding the urogenital tract, specific non-pathogenic strains of Escherichia coli and probiotic organisms were successfully applied to decrease the recurrence of local infections. The interfering ability of specific probiotic organisms (strains of Lactobacilli and Bifidobacteria) within the gastrointestinal tract against common pathogens was also demonstrated. In conclusion, randomised controlled trials are warranted to investigate the effectiveness and safety of potential applications of the principle of bacterial interference in the prevention and treatment of infections of various sites. Such trials should initially employ selected strains of probiotics for which there are preliminary data regarding their effectiveness and lack of common or serious toxicity.