Evaluation of the Efficacy of Streptococcus Salivarius Evol12® in the Reduction of Recurrent Adenotonsillitis in Children

Evaluation of the Efficacy of Streptococcus Salivarius Evol12® in the Reduction of Recurrent Adenotonsillitis in Children: A Prospective, Randomized, Double-Blind, Placebo-Controlled, Cross-over Clinical Trial

This prospective, multicenter, randomized, double-blind, placebo-controlled, cross-over clinical trial will evaluate the efficacy and safety of Streptococcus salivarius Evol12® (Bactoblis® Evol) in reducing the recurrence and duration of acute febrile adenotonsillitis in children aged 3 to 11 years. Participants will receive either the probiotic or a matching placebo for 3 months, followed by a 7-day wash-out and a second 3-month treatment period with the alternative product. The study will assess changes in the incidence and duration of adenotonsillar episodes, antibiotic use, school absences, and sleep quality.

Recurrent adenotonsillitis in children is a frequent and burdensome condition, often leading to repeated antibiotic use, missed school days, and sleep disturbances. Streptococcus salivarius is a naturally occurring commensal bacterium of the oral microbiota with demonstrated ability to inhibit Streptococcus pyogenes and other pathogens responsible for pharyngotonsillitis. Streptococcus salivarius Evol12® is a novel probiotic strain with a safe microbiological profile and no antibiotic resistance, developed to restore oral microbial balance and reduce recurrent infections of the upper airways.

This non-profit, prospective, multicenter, randomized, double-blind, placebo-controlled, cross-over study will enroll 216 pediatric participants aged 3 to 11 years with a history of at least three documented episodes of acute febrile adenotonsillitis in the preceding 12 months. Participants will be randomized to receive either one orodispersible tablet of S. salivarius Evol12® (Bactoblis® Evol, PharmExtracta S.p.A., Italy) daily in the evening for 3 months followed by placebo for 3 months, or vice versa, with a 7-day wash-out period between treatments.

The primary objective is to evaluate the efficacy of S. salivarius Evol12® in reducing the duration and recurrence of acute febrile adenotonsillitis, as measured by the Wisconsin Upper Respiratory Symptom Survey for Kids (WURSS-K).

Secondary objectives include assessment of sleep disorders (OSA-18 questionnaire), number and duration of feverish episodes, school days missed, antibiotic use, and symptom severity (e.g., sore throat, tonsil exudate, difficulty swallowing, otitis, cough, and fatigue).

Ethical approval has been granted by the Ethics Committee of the University of Urbino Carlo Bo (Minutes No. 96, July 24, 2025).

Inclusion Criteria:

• Male and female children aged 3 to 11 years.
• History of ≥3 documented episodes of acute adenotonsillitis within the previous 12 months, each characterized by fever ≥38°C.
• Signed and accepted informed consent from a parent or legal guardian.

Exclusion Criteria:

• Total obstruction of the nasal cavities.
• Uncontrolled gastroesophageal reflux disease.
• Unilateral tonsillar enlargement.
• Previous tonsil reduction surgery.
• Lack of parental or legal guardian consent to participate in the study.