Penitsilliin

Penicillin is a group of beta-lactam antibiotics produced by Penicillium species. The term penitsilliin appears to be a misspelling of penicillin. Penicillins kill bacteria by inhibiting cell wall synthesis: they bind penicillin-binding proteins and block cross-linking of peptidoglycan, leading to bacterial lysis in susceptible organisms. They are generally bactericidal and most effective against many Gram-positive bacteria, with varying activity against Gram-negatives depending on the compound.

Common penicillins include penicillin G and penicillin V, which are acid-sensitive and used orally or parenterally; ampicillin and amoxicillin extend coverage to some Gram-negative bacteria; and beta-lactamase–inhibitor combinations such as amoxicillin-clavulanate broaden activity against resistant strains. Anti-staphylococcal penicillins (nafcillin, dicloxacillin) resist some beta-lactamases.

Penicillin was discovered in 1928 by Alexander Fleming from a mold-contaminated culture of Staphylococcus. Its medical potential was realized in the 1940s through the work of Howard Florey, Ernst Boris Chain, and colleagues, leading to widespread clinical use during and after World War II.

Penicillins are used to treat streptococcal infections, certain pneumococcal infections, syphilis, and various dental and soft-tissue infections. They are generally well tolerated, but hypersensitivity reactions occur in some people, ranging from rash to anaphylaxis. Cross-reactivity with some cephalosporins is possible. Resistance by beta-lactamases or altered penicillin-binding proteins limits effectiveness in certain bacteria, such as MRSA.

Most penicillins are renally excreted and require dose adjustments in kidney impairment. Penicillin G is usually given by injection; penicillin V is oral. Oral bioavailability varies among agents, and distribution to tissues is generally good but limited in the central nervous system unless meninges are inflamed.