Which antibiotic is a type of penicillin?

Ampicillin is indeed a type of penicillin antibiotic. It belongs to the broader class of beta-lactam antibiotics, which are characterized by their unique beta-lactam ring structure. Penicillins, including ampicillin, work by interfering with the synthesis of the bacterial cell wall, leading to cell lysis and death.

Ampicillin is effective against a variety of gram-positive and some gram-negative bacteria, making it a commonly used antibiotic in clinical settings. This versatility allows it to treat various infections, including respiratory tract infections, urinary tract infections, and bacterial meningitis, among others.

In contrast, the other options listed are not penicillins. Ciprofloxacin is a fluoroquinolone antibiotic, sulfadiazine is a sulfonamide, and metronidazole is an antiprotozoal and antibiotic effective mainly against anaerobic bacteria and certain parasites. Each of these classes of antibiotics has its own mechanism of action and range of activity.