Bacterium
Gardnerella vaginalis
Clue-cell bacterial vaginosis rod
gard-nuh-REL-uh vaj-ih-NAH-lis
High-yield clue
Clue cells (vaginal epithelial cells coated with bacteria) plus a positive amine 'whiff' test and elevated vaginal pH are the classic bacterial vaginosis clues.
Overview
A pleomorphic, gram-variable facultative anaerobe that is the main marker organism of bacterial vaginosis, a polymicrobial overgrowth. It is the standard teaching example of 'clue cells'.
Classification
- Gram-variable
- Pleomorphic rod/coccobacillus
- Facultative anaerobe
- Non-motile
Lab & identification clues
- Clue cells on wet mount
- Gram-variable pleomorphic staining
- Positive amine (whiff) test with KOH
- Elevated vaginal pH above 4.5
Associations
- Bacterial vaginosis
- Loss of protective lactobacilli
- Polymicrobial overgrowth with anaerobes
Commonly confused with
- Trichomonas vaginalis
- Candida vulvovaginitis
Frequently asked questions
What is Gardnerella vaginalis?
A pleomorphic, gram-variable facultative anaerobe that is the main marker organism of bacterial vaginosis, a polymicrobial overgrowth. It is the standard teaching example of 'clue cells'.
What are the lab clues for Gardnerella vaginalis?
Lab clues for Gardnerella vaginalis include Clue cells on wet mount, Gram-variable pleomorphic staining, Positive amine (whiff) test with KOH, and Elevated vaginal pH above 4.5.
What is Gardnerella vaginalis commonly confused with?
Gardnerella vaginalis is commonly confused with Trichomonas vaginalis and Candida vulvovaginitis.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.