Rifampicin antibiotic molecule. Computer artwork showing the secondary structure of the antibiotic rifampicin. Rifampicin kills bacteria by inhibiting the enzyme RNA polymerase, which prevents the translation of mRNA (messenger ribonucleic acid) into proteins and so kills the cell. It is used to treat Mycobacterium infections, including pneumonia and leprosy, and in combination with other drugs to treat MRSA (methicillin-resistant Staphylococcus aureus).