Streptococcus salivarius K12 in pharyngotonsillitis and acute otitis media -a meta-analysis

The oral administration of Streptococcus salivarius K12 represents a valid solution for the prevention of pharyngitis or pharyngotonsillitis, of bacterial or viral origin, and/or acute otitis media. In particular, this could be an interesting alternative to antibiotic prophylaxis in patients with relapse or disease recurrence. In this regard, the studies published in the scientific literature are limited, and thus, it was of interest to provide a meta-analysis in order to analyze in more detail the results obtained in this research field. For the meta-analysis, clinical studies were selected, as identified through PubMed, which examined the relationship between the use of formulations based on Streptococcus salivarius K12 and the number of cases or episodes of pharyngitis or pharyngotonsillitis, of bacterial or viral origin, and acute otitis media in children and adults. The effect size (ES) was calculated according to Cohen using the fixed effects model (fixed effects). Seven studies met the predefined inclusion criteria and they were included in the meta-analysis. ES values equal to-1.40 [-1.67;-1.13] and-1.01 [-1.19;-0.83] were obtained for the effect of Streptococcus salivarius K12 on the prevention of pharyngitis and acute otitis media, respectively. Both values were translated into a "big effect" according to Cohen's scale. Treatment based on this strain is effective for both the prevention of pharyngitis and acute otitis media. In addition, it is further revealed that the strain is more effective in the prevention of pharyngitis. It is desirable that further clinical investigation continues to expand and update the meta-analysis work and to recommend the use of the strain as a useful prophylactic tool to reduce the events of pharyngotonsillitis and acute otitis media. 81 Streptococcus salivarius K12 in pharyngotonsillitis and acute otitis media-a meta-analysis we could assess more thoroughly the results obtained in this research field, comparing the results differentially for pharyngitis and bacterial infections of the ear. Materials and methods The studies were sourced from scientific and biomedical journals and through the use of the PubMed database. To be included in the meta-analysis, the studies had to meet the following inclusion criteria: (a) clinical trials; (b) parallel studies; or (c) historical control studies; (d) studies in which the effectiveness of basic formulations of Streptococcus salivarius K12 ATCC BAA-1024 was assessed; (e) studies that reported the number of cases or episodes of pharyngitis or pharyngotonsillitis of bacterial or viral infection and/or AOM; (f) studies in which paediatric patients or adults were enrolled. At first, the inclusion of keywords such as "BLIS K12", "Streptococcus salivarius K12", "pro-biotic Streptococcus salivarius K12" and "bacte-riocin-like inhibitory substances Streptococcus salivarius K12" produced a number of records equal to 103 publications; after eliminating duplicates, this was reduced to 43, of which 28 were screened articles. Finally, there was a total of 21 studies excluded, while seven were included in the meta-analysis. Although one study complied with the predefined inclusion criteria [14] , it was not included in the final quantitative analysis because of a characteristic that differed significantly between treated subjects and controls. More precisely, children diagnosed with recurrent streptococcal pharyngitis (mean > three episodes of pharyngotonsillitis during the year before the study) were included in the treatment group, while children without a diagnosis of recurrent disease were enrolled in the control group.