Ampicillin

Introduction

Ampicillin is a beta-lactam antibiotic that has been widely used since the 1960s. It belongs to the aminopenicillin class of antibiotics, which are derivatives of the basic penicillin structure. Ampicillin is used to treat a variety of bacterial infections by inhibiting the synthesis of bacterial cell walls.

A close-up image of ampicillin capsules.

History and Development

The discovery and development of ampicillin marked a significant breakthrough in the treatment of bacterial infections. It was discovered in 1958 by a team of researchers at the British company Beecham Research Laboratories. The antibiotic was introduced to the market in 1961 and was the first of the aminopenicillins, a subgroup of penicillins with broad-spectrum activity.

Chemistry

Ampicillin is chemically known as (2S,5R,6R)-6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid. It is a derivative of penicillin, with an additional amino group that enhances its spectrum of antibacterial activity.

Mechanism of Action

Ampicillin's mechanism of action involves the inhibition of bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall. This binding inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls, leading to cell lysis.

Medical Uses

Ampicillin is used to treat a variety of bacterial infections, including respiratory tract infections, urinary tract infections, meningitis, salmonellosis, and endocarditis. It is also used for prophylaxis in individuals at high risk of bacterial infections.

Side Effects and Adverse Reactions

Common side effects of ampicillin include rash, nausea, and diarrhea. Serious adverse reactions, although rare, can include anaphylaxis and severe skin reactions.

Resistance

The widespread use of ampicillin has led to the emergence of ampicillin-resistant strains of bacteria. Resistance to ampicillin is often mediated by beta-lactamase enzymes, which hydrolyze the beta-lactam ring of ampicillin, rendering it ineffective.