''Gardnerella vaginalis'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of Gram-variable-staining facultative anaerobic

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

. The organisms are small (1.0–1.5 μm in diameter) non-spore-forming, nonmotile coccobacilli. Once classified as ''Haemophilus vaginalis'' and afterwards as ''Corynebacterium vaginalis'', ''G. vaginalis'' grows as small, circular, convex, gray colonies on

chocolate agar Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating ...

; it also grows on agar. A selective medium for ''G. vaginalis'' is

colistin Colistin, also known as polymyxin E, is an antibiotic medication used as a last-resort treatment for multidrug-resistant Gram-negative infections including pneumonia. These may involve bacteria such as ''Pseudomonas aeruginosa'', '' Klebsiella ...

- oxolinic acid blood agar.

Clinical significance

''G. vaginalis'' is a facultatively anaerobic Gram-variable rod that is involved, together with many other bacteria, mostly anaerobic, in bacterial vaginosis in some women as a result of a disruption in the normal

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

microflora Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found to ...

. The resident facultative anaerobic ''

Lactobacillus ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...

'' population in the vagina is responsible for the acidic environment. Once the anaerobes have supplanted the normal vaginal bacteria, prescription

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

with anaerobic coverage may have to be given to re-establish the equilibrium of the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

. ''G. vaginalis '' is not considered the cause of the bacterial vaginosis, but a signal organism of the altered microbial ecology associated with overgrowth of many bacterial species. While typically isolated in

genital A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...

cultures, it may also be detected in other samples from

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...

, and the

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its st ...

. Although ''G. vaginalis'' is a major species present in bacterial vaginosis, it can also be isolated from women without any signs or symptoms of infection. It has a Gram-positive cell wall, but, because the cell wall is so thin, it can appear either

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

under the microscope. It is associated microscopically with

clue cell Clue cells are epithelial cells of the vagina that get their distinctive stippled appearance by being covered with bacteria. The etymology behind the term "clue" cell derives from the original research article from Gardner and Dukes describing the ...

s, which are epithelial cells covered in bacteria. ''G. vaginalis'' produces a pore-forming toxin, vaginolysin, which affects only human cells.

Protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...

and

sialidase Exo-α-sialidase (EC 3.2.1.18, sialidase, neuraminidase; systematic name acetylneuraminyl hydrolase) is a glycoside hydrolase that cleaves the glycosidic linkages of neuraminic acids: : Hydrolysis of α-(2→3)-, α-(2→6)-, α-(2→8)- glycos ...

enzyme activities frequently accompany ''G. vaginalis''.

Treatment

Methods of antibiotic treatment include

metronidazole Metronidazole, sold under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It i ...

and clindamycin, in both oral and vaginal gel/cream forms. The effectiveness of treating bacterial vaginosis with antibiotics is well documented, however relapse is not uncommon.

Symptoms

''G. vaginalis'' is associated with bacterial vaginosis, which may be asymptomatic, or may have symptoms including vaginal discharge, vaginal irritation, and a "fish-like" odor. In the amine whiff test, 10% KOH is added to the discharge; a positive result is indicated if a fishy smell is produced. This and other tests can be used to distinguish between vaginal symptoms related to ''G. vaginalis'' and those caused by other organisms, such as '' Trichomonas'' and ''

Candida albicans ''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...

'', which are similar and may require different treatment. ''

Trichomonas vaginalis ''Trichomonas vaginalis'' is an anaerobic, flagellated protozoan parasite and the causative agent of a sexually transmitted disease called trichomoniasis. It is the most common pathogenic protozoan that infects humans in industrialized countri ...

'' and ''G. vaginalis'' have similar clinical presentations and can cause a frothy gray or yellow-green vaginal discharge, pruritus, and produce a positive "whiff-test". The two can be distinguished using a wet-mount slide, where a swab of the

vaginal epithelium The vaginal epithelium is the inner lining of the vagina consisting of multiple layers of (squamous) cells. The basal membrane provides the support for the first layer of the epithelium-the basal layer. The intermediate layers lie upon the basal ...

is diluted and then placed onto a slide for observation under a microscope. ''Gardnerella'' reveals a classic "

" under the microscope, showing bacteria adhering to the surface of

squamous Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...

epithelial cells.

References

External links

*
Type strain of ''Gardnerella vaginalis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{DEFAULTSORT:Gardnerella vaginalis Bifidobacteriales Bacterial diseases Infections with a predominantly sexual mode of transmission Bacterial vaginosis Bacteria described in 1955

Clinical significance

Treatment

Symptoms

See also

References

External links