Tuberculosis resulting from infection with Mycobacterium tuberculosis (Mtb) is a serious global health problem accounting for 1.7 million deaths in 2016. A major reason for the high morbidity and mortality caused by Mtb is the long duration of therapy and increasing multidrug-resistance of Mtb strains. Mtb has been treated with combination therapy for over fifty years. Yet according to the latest WHO statistics, approximately half a million new cases of multidrug-resistant tuberculosis are diagnosed every year. Of these, it is estimated that approximately 40,000 have extensively drug-resistant tuberculosis. In view of these numbers, there is a medical need for new anti-Mtb compounds to overcome resistance to known drugs in patients. The inventors were able to demonstrate that lansoprazole and derivatives thereof exhibit growth inhibiting properties against intracellular Mtb. In particular, it has been proven that the reduced form lansoprazole sulfide is the active moiety. Yet, lansoprazole is not metabolized in a sufficient amount to serve as a prodrug. Thus, the inventors propose lansoprazole sulfide (LPZS) as a new drug to treat Mtb infections.