Acute diarrhea is a serious disease with potentially harmful consequences, especially in childhood. Probiotics are generally used in the treatment of acute diarrhea. A case of a 17-year-old female patient with cerebral palsy who developed sepsis after using a commercial preparation containing Bacillus clausii (Alkalihalobacillus clausii) is presented. Colonies isolated from blood cultures were identified as Bacillus clausii (A. clausii) by the Vitek-2 automated system and confirmed by MALDI TOF-MS. The antibiotic susceptibility pattern of the A. clausii strain produced from the probiotic preparation was determined as most likely the same as the one isolated from the patient. The patient was treated with teicoplanin. To the best of our knowledge after literature reviw, our case is the first A. clausii sepsis case reported in Türkiye. Probiotic preparations should be used with caution, especially in immunocompromised patients.