A tiacumicin compound, a stereo-isomer thereof, a polymorph thereof or a pharmaceutically acceptable solvate thereof, and a pharmaceutical composition, containing a tiacumicin compound, a stereo-isomer thereof, a polymorph thereof or a pharmaceutically acceptable solvate thereof, are provided for use in the oral treatment of Clostridium difficile infections (CDI) or Clostridium difficile associated diarrhea or disease (CDAD) in a patient in accordance with a dosage regimen selected from the group consisting of: i. Administering 200 mg of the tiacumicin compound BID for 5 days followed by 5 days of rest and then 200 mg once daily for a further 10 days and ii. Administering 200 mg of the tiacumicin compound BID for 5 days followed by a single 200 mg every other day for 20 days.Further, a method is provided for recovering of gut Bifidobacteria population in a patient, suffering from Clostridium difficile infections (CDI) or Clostridium difficile associated diarrhea or disease (CDAD) and receiving oral treatment with a tiacumicin compound, from 50 to 90% of the gut Bifidobacteria population prior to administering the tiacumicin compound during days 15-45 after start of the treatment by orally administering the tiacumicin compound to the patient according to a dosage regimen, which is selected from the above-mentioned group.Se propune un compus al tiacumicinei, un stereoizomer al acesteia, un polimorf al acesteia sau un solvat farmaceutic acceptabil al acesteia şi o compoziţie farmaceutică, ce conţine un compus al tiacumicinei, un stereoizomer al acesteia, un polimorf al acesteia sau un solvat farmaceutic acceptabil al acesteia utilizate în tratamentul oral al infecţiilor provocate de Clostridium difficile (CDI) sau diareii, sau bolii asociate cu Clostridium difficile (CDAD) la pacient în conformitate cu un regim de dozare selectat din grupul ce constă din: i - administrarea a 200 mg de compus tiacumicinic BID, timp de 5 zile, urmate de 5 zile de repaos, apoi 200 mg odat
