Gardnerella: Difference between revisions
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== Overview == | == Overview == | ||
'''Gardnerella''' is a [[genus]] of [[Gram staining|gram-variable]] [[bacteria]] of which '''Gardnerella vaginalis''' is the only species. Gardnerella vaginalis can cause [[bacterial vaginosis]] in some women. | '''Gardnerella''' is a [[genus]] of [[Gram staining|gram-variable]] [[bacteria]] of which '''Gardnerella vaginalis''' is the only species. Gardnerella vaginalis can cause [[bacterial vaginosis]] in some women. | ||
Gardnerella vaginalis, formerly known as Haemophilus vaginalis and Corynebacterium vaginale, is a facultative anaerobic, nonmotile, pleomorphic gram-negative to gram-variable rod bacteria. It is a well-recognized colonizer of the female genital tract and survives high pH.<ref name="pmid1624577">{{cite journal| author=Smith SM, Ogbara T, Eng RH| title=Involvement of Gardnerella vaginalis in urinary tract infections in men. | journal=J Clin Microbiol | year= 1992 | volume= 30 | issue= 6 | pages= 1575-7 | pmid=1624577 | doi= | pmc=265332 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1624577 }} </ref> | |||
It also survives poorly in human urine at 37 degrees C.<ref name="pmid1992615">{{cite journal| author=Lam MH, Birch DF| title=Survival of Gardnerella vaginalis in human urine. | journal=Am J Clin Pathol | year= 1991 | volume= 95 | issue= 2 | pages= 234-9 | pmid=1992615 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1992615 }} </ref> | |||
G. vaginalis was first recognized by Leopold and named Haemophilus vaginalis by Gardner and Dukes in 1955 because it was isolated on human blood bilayer agar media.<ref name="pmid1498765">{{cite journal| author=Catlin BW| title=Gardnerella vaginalis: characteristics, clinical considerations, and controversies. | journal=Clin Microbiol Rev | year= 1992 | volume= 5 | issue= 3 | pages= 213-37 | pmid=1498765 | doi= | pmc=358241 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1498765 }} </ref> | |||
This method of isolation did not yield great amounts of bacteria and therefore, was introduced with Tween 80 (HBT medium) or without Tween 80 (HB medium). HB medium consists of a basal layer of Columbia agar base containing colistin and naladixic acid with added amphotericin B and an overlayer of the same composition plus 5% human blood. HBT agar also contains Proteose Peptone No. 3 (Difco Laboratories) and Tween 80 in the basal layer and the overlayer. Both Tween 80 and the bilayer composition enhanced G. vaginalis production of human blood hemolysis, permitting detection of this organism even in the presence of heavy growth of other vaginal flora. G. vaginalis is resistant to lactobacillus and many antibiotics such as tetracycline. Thus, it is important to sequence its genome to find out what makes it resistant and what genes are expressed in the genome that makes it resistant.<ref name=Isolation-of-Gardnerella> Totten PA, R Amsel, J Hale, PPiot, KK Holmes. "Selective differential human blood bilayer media for isolation of Gardnerella (Haemophilus) vaginalis." J Clin Microbiol. 1982 Jan ;15 (1):141-7</ref> | |||
===Laboratory Findings=== | ===Laboratory Findings=== | ||
====Culture==== | ====Culture==== | ||
Revision as of 16:01, 12 October 2016
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];
Overview
Gardnerella is a genus of gram-variable bacteria of which Gardnerella vaginalis is the only species. Gardnerella vaginalis can cause bacterial vaginosis in some women.
Gardnerella vaginalis, formerly known as Haemophilus vaginalis and Corynebacterium vaginale, is a facultative anaerobic, nonmotile, pleomorphic gram-negative to gram-variable rod bacteria. It is a well-recognized colonizer of the female genital tract and survives high pH.[1] It also survives poorly in human urine at 37 degrees C.[2] G. vaginalis was first recognized by Leopold and named Haemophilus vaginalis by Gardner and Dukes in 1955 because it was isolated on human blood bilayer agar media.[3]
This method of isolation did not yield great amounts of bacteria and therefore, was introduced with Tween 80 (HBT medium) or without Tween 80 (HB medium). HB medium consists of a basal layer of Columbia agar base containing colistin and naladixic acid with added amphotericin B and an overlayer of the same composition plus 5% human blood. HBT agar also contains Proteose Peptone No. 3 (Difco Laboratories) and Tween 80 in the basal layer and the overlayer. Both Tween 80 and the bilayer composition enhanced G. vaginalis production of human blood hemolysis, permitting detection of this organism even in the presence of heavy growth of other vaginal flora. G. vaginalis is resistant to lactobacillus and many antibiotics such as tetracycline. Thus, it is important to sequence its genome to find out what makes it resistant and what genes are expressed in the genome that makes it resistant.[4]
Laboratory Findings
Culture
Once classified as a species of Haemophilus, G. vaginalis grows as small, circular, convex, gray colonies on chocolate agar; it will also grow on HBT agar. A selective medium for G. vaginalis is colistin-oxolinic acid blood agar.
While typically isolated in genital cultures, it may also be detected from other sources, such as blood, urine and pharynx. Although a chief cause of bacterial vaginosis, it may be isolated from women without any signs or symptoms of infection.
Microscopy
Under the microscope it appears as a gram-negative rod, although it has been reported to have a gram-positive cell wall. It is associated microscopically with clue cells, which are epithelial cells covered in bacteria.
Shown below is an image of clue cells
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Reactions
Infections with G. vaginalis go along with proteolysis, giving nitrous products such as cadaverines and putrescines, which can cause a bad smell and loss of water.
Treatment
Medical Therapy
One method of treatment is metronidazole.
References
- ↑ Smith SM, Ogbara T, Eng RH (1992). "Involvement of Gardnerella vaginalis in urinary tract infections in men". J Clin Microbiol. 30 (6): 1575–7. PMC 265332. PMID 1624577.
- ↑ Lam MH, Birch DF (1991). "Survival of Gardnerella vaginalis in human urine". Am J Clin Pathol. 95 (2): 234–9. PMID 1992615.
- ↑ Catlin BW (1992). "Gardnerella vaginalis: characteristics, clinical considerations, and controversies". Clin Microbiol Rev. 5 (3): 213–37. PMC 358241. PMID 1498765.
- ↑ Totten PA, R Amsel, J Hale, PPiot, KK Holmes. "Selective differential human blood bilayer media for isolation of Gardnerella (Haemophilus) vaginalis." J Clin Microbiol. 1982 Jan ;15 (1):141-7