<unk>  is typically applied as a topical preparation, such as<unk> sporin<unk> /polymyxin B/bacitracin). The antibiotic can also be administered orally, in which case it is usually combined with other antibiotics.<unk>  is not absorbed from the gastrointestinal tract and has been used as a preventive measure for hepatic encephalopathy and hypercholesterolemia. By killing bacteria in the intestinal tract,<unk>  keeps ammonia levels low and prevents hepatic encephalopathy, especially before gastrointestinal surgery. Waksman and Lechevalier originally noted that<unk>  was active against streptomycin-resistant bacteria as well as Mycobacterium tuberculosis, the causative agent for tuberculosis.<unk>  has also been used to treat small intestinal bacterial overgrowth.<unk>  is not administered via injection, as it is extremely nephrotoxic (damaging to kidney function) even when compared to other aminoglycosides. The exception is when<unk>  is included, in small quantities, as a preservative in some vaccines – typically 25 μg per dose. Spectrum Similar to other aminoglycosides,<unk>  has excellent activity against gram-negative bacteria and is partially effective against gram-positive bacteria. It is relatively toxic to humans, with allergic reactions noted as a common adverse reaction (see: hypersensitivity). Physicians sometimes recommend using antibiotic ointments without<unk> , such as Polysporin. The following represents minimum inhibitory concentration (MIC) susceptibility data for a few medically significant gram-negative bacteria. *Enterobacter cloacae: >16 μg/ml *Escherichia coli: 1 μg/ml *Proteus vulgaris: 0.25 μg/ml
Neomycin
Dactinomycin
Anisomycin
Paromomycin
Capreomycin
Boromycin
Bicyclomycin
Valrubicin