Used primarily as a broad-spectrum antibiotic, it treats a variety of bacterial infections, especially in settings where other antibiotics are ineffective or cannot be used. It is effective against both gram-positive and gram-negative bacteria and exhibits good penetration into the brain and various tissues, making it beneficial for infections in hard-to-reach organs. Common applications include treatment of typhoid fever, meningitis, rickettsial diseases, and bloodstream infections. Due to the risk of serious side effects like bone marrow suppression, its use is often reserved for severe infections when safer alternatives are not available. It is also used in topical forms for eye infections such as conjunctivitis and in laboratory settings as a selective agent in microbiological culture media.