Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
ampicillin(ăm'pĭsĭl`ĭn), a penicillinpenicillin,
any of a group of chemically similar substances obtained from molds of the genus Penicillium that were the first antibiotic agents to be used successfully in the treatment of bacterial infections in humans.
..... Click the link for more information. -type antibioticantibiotic,
any of a variety of substances, usually obtained from microorganisms, that inhibit the growth of or destroy certain other microorganisms. Types of Antibiotics
..... Click the link for more information. that is effective against both gram-negative microorganisms and gram-positive microorganisms such as Escherichia coli. It is often used in the treatment of urinary tract infections, but resistant organisms are increasingly common (see drug resistancedrug resistance,
condition in which infecting bacteria can resist the destructive effects of drugs such as antibiotics and sulfa drugs. Drug resistance has become a serious public health problem, since many disease-causing bacteria are no longer susceptible to previously
..... Click the link for more information. ). Like other penicillin antibiotics, ampicillin acts against bacteria by inhibiting the synthesis of bacterial cell wall components.