The primary treatment for bacterial infections involves the use of antibiotics. An antibiotic is a type of antimicrobial. Antibiotics have played a key role in improving life expectancy around the world since the 1940s. The first wave of antibiotics were beta-lactam (β-lactam) antibacterials, which include the penicillins (produced by fungi in the genus Penicillium). Other major classes of antibiotics include cephalosporins (a class of antibiotics originally derived from the fungus Acremonium), aminoglycosides (a portion of a molecule composed of amino-modified sugars), fluoroquinolones (a family of synthetic broad-spectrum antibacterial drugs), and carbapenems (the antibiotics of last resort for many bacterial infections). Early types of antibiotics were derived only from microorganisms, such as fungi; later generations of antibiotics were prepared synthetically (such as the sulphonamides).

Doses of antibiotics ...