gram-negative
adjective
gram-neg·a·tive
ˈgram-ˈne-gə-tiv 
: not holding the purple dye when stained by Gram's stain
—used chiefly of bacteria
Examples of gram-negative in a Sentence
Recent Examples on the Web
The peptide was particularly effective against gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae.
—
Michael Franco, New Atlas, 26 Mar. 2025
Tate, who is vice president of sales for Mid-Florida Pathology, convinced doctors to administer gram-negative medications, which worked.
—Edward Lee, Baltimore Sun, 23 Jan. 2025
The team focused its search for a new drug on compounds that suppress the Lol system, which shuttles lipoproteins between the inner and outer membranes in gram-negative bacteria.
—Tribune News Service, The Mercury News, 20 June 2024
Bacteria populations in the average human gut are roughly split between gram-negative and gram-positive types, said Kristen Munoz, a former doctoral student at the University of Illinois who co-led the study.
—Corinne Purtill, Los Angeles Times, 12 June 2024
Encased in both an inner and outer membrane that antibiotics struggle to cross, gram-negative bacteria are resistant to most currently available therapies.
—Corinne Purtill, Los Angeles Times, 3 Jan. 2024
Shigella bacteria are gram-negative bacteria, shaped like rods, recognized worldwide as the most common cause of dysentery, a gastrointestinal illness resulting in severe diarrhea.
—CBS News, 1 Mar. 2023
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Michael Franco, New Atlas, 26 Mar. 2025
Tate, who is vice president of sales for Mid-Florida Pathology, convinced doctors to administer gram-negative medications, which worked.
—Edward Lee, Baltimore Sun, 23 Jan. 2025
The team focused its search for a new drug on compounds that suppress the Lol system, which shuttles lipoproteins between the inner and outer membranes in gram-negative bacteria.
—Tribune News Service, The Mercury News, 20 June 2024
Bacteria populations in the average human gut are roughly split between gram-negative and gram-positive types, said Kristen Munoz, a former doctoral student at the University of Illinois who co-led the study.
—Corinne Purtill, Los Angeles Times, 12 June 2024
Encased in both an inner and outer membrane that antibiotics struggle to cross, gram-negative bacteria are resistant to most currently available therapies.
—Corinne Purtill, Los Angeles Times, 3 Jan. 2024
Shigella bacteria are gram-negative bacteria, shaped like rods, recognized worldwide as the most common cause of dysentery, a gastrointestinal illness resulting in severe diarrhea.
—CBS News, 1 Mar. 2023
Cite this Entry
“Gram-negative.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/gram-negative. Accessed 2 May. 2025.
Copy CitationMedical Definition
gram-negative
adjective
gram-neg·a·tive
ˈgram-ˈneg-ət-iv
: not holding the purple dye when stained by Gram's stain
—used chiefly of bacteria
Love words? Need even more definitions?
Merriam-Webster unabridged
Share