Ampicillin is an antibiotic belonging to the aminopenicillin class of the penicillin family. The drug is used to prevent and treat several bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, salmonellosis, and endocarditis. [6] Ampicillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name penicillin can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Ampicillin is a type of penicillin antibiotic that treats some bacterial infections. The brand name of this medication is Principen. Ampicillin is an antibiotic that is commonly used for infections caused by certain bacteria. Ampicillin may not be appropriate for all infections, depending on which germs are causing the. Detailed Ampicillin dosage information for adults and children. Includes dosages for Bacterial Infection, Urinary Tract Infection, Sinusitis and more; plus renal, liver and dialysis adjustments. Ampicillin Injection: learn about side effects, dosage, special precautions, and more on MedlinePlus Ampicillin: learn about side effects, dosage, special precautions, and more on MedlinePlus What is ampicillin? Ampicillin is a penicillin antibiotic that is used to treat or prevent many different types of infections such as bladder infections, pneumonia, gonorrhea, meningitis, or infections of the stomach or intestines. Ampicillin is an antibiotic used for treating infections of the middle ear, sinuses, stomach and intestines, bladder, and kidney caused by susceptible bacteria. It also is used for treating uncomplicated gonorrhea, meningitis, endocarditis, and other serious infections. Ampicillin is a prescription penicillin-type antibiotic used to treat many different types of infections caused by bacteria, such as ear infections, bladder infections, pneumonia, gonorrhea, and E. coli or salmonella infection.