What does cycloserine mean?
Cycloserine is a synthetic antibiotic whose natural form is produced by certain soil bacteria such as Streptomyces. Structurally, it is a cyclic analogue of the amino acid serine, which explains its name and much of its biological behaviour. In medicine it serves chiefly as a second-line treatment for multidrug-resistant tuberculosis, deployed when first-line drugs such as isoniazid prove ineffective. Because it can penetrate the central nervous system and interact with neurotransmitter systems, cycloserine has also attracted attention in neuroscience research on learning and fear extinction. Its use demands care: it can cause neurological side effects, including headaches, drowsiness, and in higher doses seizures or psychiatric symptoms, so patients are monitored throughout therapy. The word itself belongs to specialist vocabulary, appearing in pharmacology texts, prescribing information, and medical journals rather than everyday conversation.
nounA broad-spectrum antibiotic produced by certain bacteria and made synthetically, used chiefly as a second-line treatment for tuberculosis. Chemically, it is a cyclic analogue of the amino acid serine.
- An antibiotic (the D-form is active) used mainly as a second-line agent against multidrug-resistant tuberculosis.
"When the patient's tuberculosis proved resistant to first-line drugs, the physician added cycloserine to the regimen."
"The treatment protocol included cycloserine after standard drugs failed to clear the infection."
"Because cycloserine can affect the central nervous system, patients taking it are monitored closely for mood changes."
As a chemical substance and medication, cycloserine is treated as uncountable and takes no plural form.
"The pharmacy stocked cycloserine in both capsule and syrup forms."
This antibiotic, born from soil bacteria, is so chemically close to a brain-signalling amino acid that researchers have studied it to help extinguish phobias and anxiety.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cycloserine
Cycloserine combines the prefix 'cyclo-', from Greek kyklos meaning circle or wheel, with 'serine', an amino acid whose name derives from Latin sericum, meaning silk. The compound was identified in the mid-twentieth century among fermentation products of Streptomyces bacteria and was subsequently manufactured synthetically. Its name reflects its chemistry rather than any poetic origin: a ring-shaped relative of serine. Related words sharing these roots include other amino-acid names built on biochemical nomenclature, as well as the broad family of '-ine' compound names in chemistry.
How cycloserine is actually used
A technical term confined largely to medicine, pharmacology, and biochemistry. In clinical writing it often appears in its enantiomer form as 'D-cycloserine', since only the D-form has antibiotic activity.
Easily confused with cycloserine
Serine is a common amino acid found in proteins, whereas cycloserine is a cyclic derivative of serine used as an antibiotic drug.