In the practice of a pediatrician, among all detected infectious diseases, acute respiratory infections (ARI) continue to lead. The causes of respiratory infections can be varied. Great importance is attached to the normal microflora, as one of the main regulatory factors that can ensure the adaptation of children to different living conditions, and is responsible for maintaining homeostasis and maturation of the immune system. It has now been established that a healthy oral microbiome is the key to somatic health, and one of the important components of anti-infective protection. Therefore, one of the promising areas for the prevention of respiratory infections is the use of oral probiotics. The article provides an overview of findings from the studies on the efficacy and safety of the probiotic strain Streptococcus salivarius K12 showing inhibitory activities against the main respiratory pathogens – Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis. S. salivarius K12 produces the bacteriocin-like inhibitory substance BLIS K12 (Bacteriocin-Like Inhibitory Substance), which plays an important role in maintaining the natural flora of the upper respiratory tract. It has been proven that the use of S. salivarius K12 results in a reduction of the level of pathogen colonization of the oropharyngeal mucosa, a rapid decline of the clinical symptoms of acute and chronic diseases of the ENT organs, and the prevention of acute respiratory diseases. The reason for this is that the intake of S. salivarius K12 increases the amount of interferon γ in saliva, stimulating the adaptive immunity against many viral infections. S. salivarius K12 is included in the clinical guideline on acute tonsillopharyngitis for the prevention of relapses, as well as the recovery of the normal biota of the oropharyngeal mucosa after disease.
