Xylistin 1 MIU Injection Xylistin 1 MIU is an injectable antibiotic containing colistimethate sodium, a medicine reserved for treating serious bacterial infections caused by susceptible bacteria, particularly certain difficult-to-treat Gram-negative organisms. It works by damaging the bacterial cell membrane, which ultimately leads to bacterial cell death. The product is supplied as a powder that must be prepared before use and may be administered by intravenous infusion or used for inhalation according to the prescribed treatment. It is generally used in hospital or specialist-care settings.