Background: This systematic review aimed to synthesize the existing evidence on the use of Streptococcus salivarius (S. salivarius) probiotics as prophylactic or therapeutic tools for pediatric oral, dental, and respiratory diseases. Methods: A comprehensive search was carried out across multiple databases using the following terms: S. salivarius, probiotic, children, pediatric. Results: The systematic literature search identified 613 publications, which were meticulously screened, and, ultimately, 15 suitable citations were included in this systematic review. Three strains of S. salivarius (M18, K-12, 24SMB) were used, and they all demonstrated positive benefits in pediatric pathology. Conclusions: Administration of S. salivarius has benefits, is effective, and is convenient (cost-effective) in pediatric prophylaxis. Oral administration as a chewable tablet or powder of S. salivarius M18 for 3 months is able to reduce the incidence of black stains, plaque, and tooth decay in children. S. salivarius K-12 treatment decreased the occurrence of pharyngeal, recurrent, and streptococcal disease, and the benefits also extend to a reduction of nonstreptococcal diseases, including tracheitis, viral pharyngitis, rhinitis, flu, laryngitis, acute otitis media, and enteritis. Administration of S. salivarius 24SMB as an intranasal spray was able to reduce the risk of acute otitis media in children prone to this condition.

Circulating biomarkers have been proposed for early identification of aortic dilatation progression associated with bicuspid aortic valve (BAV), but matrix metalloproteinases (MMPs) are distinguished as signatures of increased extracellular matrix degradation, a landmark of aneurysm formation. The current study aims to identify the role of MMP-1, MMP-2, MMP-9, and the MMP inhibitor, TIMP-1, in identifying aortic dilation in children with BAV. We conducted a study on 73 children divided into two study groups, depending on the presence of aortic dilatation (group 1–43 BAV controls and group 2–30 children with BAV and aortic dilatation). Each patient underwent a cardiac ultrasound and, in each case, serum MMP-1, MMP-2, MMP-9, and TIMP-1 were quantified using xMAP technology. Comparison of the MMPs between the two study groups revealed significantly higher values only in the case of TIMP-1, among BAV controls. Moreover, the same TIMP-1 inversely correlated with aortic annulus absolute size and z score, as well as with ascending aorta z score. No particular correlation between the aortic phenotype and the presence of aortic dilatation was found. Future longitudinal research starting at pediatric ages could show the significance of MMPs screening in BAV individuals as predictors of aortic aneurysm formation.

Streptococcus salivarius (S. salivarius) is a prominent oral commensal bacterium with probiotic potential and relevance to both oral and systemic health. Accurate and accessible methods for quantitative measurement of this species are needed to support microbiota studies and clinical interventions. We describe a simple, low-cost, culture-based method for quantifying S. salivarius in human saliva using Mitis-Salivarius Agar. Saliva samples from 18 healthy adult volunteers were analyzed through serial dilutions and selective plating. CFU (colony forming unit)/mL were calculated after 24 and 48 h incubation. The method proved reliable for quantifying S. salivarius in concentrations ranging from 5.8 × 10⁵ to 6.1 × 10⁸ CFU/mL. Although Mitis-Salivarius Agar is a standard medium, we demonstrate its systematic validation and optimization for human saliva in a low-resource clinical setting, where molecular tools are often unavailable.