Gentamicin is a strong antibiotic that is used to treat the most serious bacterial infections It can only be given by injection or through an IV. Gentamicin can damage kidneys and impair hearing, so it must only be administered in extreme emergencies, according to Hesperian Health Guides.
Not all antibiotics work for every bacteria, so the strength and effectiveness of an antibiotic varies depending on the infection that requires treatment. Penicillin was the first antibiotic in use and is still effective for some illnesses, but many infections have evolved to become resistant to penicillin. Broad spectrum antibiotics in the penicillin family that are more effective than penicillin alone are ampicillin and amoxicillin, says Hesperian Health Guides.
Erythromycin is an antibiotic that works on many of the same infections as those treated by medicines in the penicillin family, but the drug is usually more expensive. Erythromycin is more effective than penicillin in treating pneumonia. It is also effective against diphtheria and pertussis, reports Hesperian Health Guides.
Cotrimoxazole is a combination of two antibiotics, sulfamethoxazole with trimethoprim, and effectively treats a broad-spectrum of infections, including bladder infections, ear infections and typhoid. It is especially effective in treating the many infections that may occur with HIV, according to Hesperian Health Guides.