: a penicillin C16H19N3O4S that is effective against gram-negative and gram-positive bacteria and is used to treat various infections of the urinary, respiratory, and intestinal tracts

Examples of ampicillin in a Sentence

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Additionally, the researchers discovered that the hemolymph proteins improved the effectiveness of conventional antibiotics ampicillin, gentamicin, trimethoprim and ciprofloxacin by two- to 32-fold against clinically important bacteria. New Atlas, 21 Jan. 2025 More than 80 percent of infections are caused by E. coli, and in a 2022 report, the World Health Organization found that one in five UTI infections caused by E. coli showed reduced susceptibility to standard antibiotics like ampicillin, co-trimoxazole, and fluoroquinolones. Emily Mullin, WIRED, 10 Sep. 2024

Word History

Etymology

am(ino) + p(en)icillin

First Known Use

1961, in the meaning defined above

Time Traveler
The first known use of ampicillin was in 1961

Dictionary Entries Near ampicillin

Cite this Entry

“Ampicillin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ampicillin. Accessed 18 Feb. 2025.

Medical Definition

ampicillin

noun
: a penicillin C16H19N3O4S that is effective against gram-negative and gram-positive bacteria and is used in anhydrous forms, as the trihydrate, or as the sodium salt to treat various infections of the urinary, respiratory, and intestinal tracts see penbritin

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