are: Mycobacterium tuberculosis — 0.002 – 64 µg/ml Mycobacterium bovis — 0.125 µg/ml Staphylococcus aureus (methicillin resistant) — ≤ 0.006–256 µg/ml Chlamydia pneumoniae — 0.005 µg/ml Primary biliary cholangitis Rifampicin is used to treat itchiness caused by primary biliary cholangitis. The treatment-related adverse effects include hepatotoxicity, nephrotoxicity, hemolysis, and interactions with other drugs. For those reasons as well as some ethical concerns regarding off-label use of antibiotics, rifampin as a very effective preventive antibiotic for meningitis, is not considered appropriate for itchiness. Hidradenitis suppurativa Rifampicin with clindamycin has been used to treat the skin disease hidradenitis suppurativa. Adverse effects The most serious adverse effect is hepatotoxicity, and people receiving it often undergo baseline and frequent liver function tests to detect early liver damage. The more common side effects include fever, gastrointestinal disturbances, rashes, and immunological reactions. Taking rifampicin usually causes certain bodily fluids, such as urine, sweat, and tears, to become orange-red in color, a benign side effect that nonetheless can be frightening if it is not expected. This may also be used to monitor effective absorption of the drug (if drug color is not seen in the urine, the patient may wish to move the drug dose farther in time from food or milk intake). The discolorization of sweat and tears is not directly noticeable, but sweat may stain light clothing orange, and tears may permanently stain soft contact lenses. Since rifampicin may be excreted in breast milk, breastfeeding should be avoided while it is being taken. Other adverse effects include: Liver toxicity—hepatitis, liver failure in severe cases Respiratory—breathlessness Cutaneous—flushing, pruritus, rash, hyperpigmentation, redness and watering of eyes Abdominal — nausea, vomiting, abdominal cramps, diarrhea Flu-like symptoms—chills, fever, headache, arthralgia, and malaise. Rifampicin has good penetration into the brain, and this may directly explain some malaise and dysphoria in a minority of users. Allergic reaction—rashes, itching, swelling of the tongue or throat, severe dizziness, and trouble breathing Chemical structure Rifampicin is a polyketide belonging to the chemical class of compounds termed ansamycins, so named because of their heterocyclic structure containing a naphthoquinone core spanned by an aliphatic ansa chain. The naphthoquinonic chromophore gives rifampicin its characteristic red-orange crystalline color. The critical functional groups of rifampicin in its inhibitory binding of bacterial RNA polymerase are the four critical hydroxyl groups of the ansa bridge and the naphthol ring, which form hydrogen bonds with amino acid residues on the protein. Rifampicin