Gardnerella vaginalis started a controversy due to different interpretations of its clinical significance, taxonomic position, and Gram stain reaction. The organism was first named Haemophilus vaginalis. However, it lacked some of the characteristics the Haemophilus species required. It was then referred to as Corynebacterium vaginale. It was later changed to Gardnerella vaginalis when a new genus was necessary (Catlin, 1992). This paper will focus on the characteristics of G. vaginalis and how it is identified.
G. vaginalis cells are gram-negative to gram-variable. These cells are nonmotile, small, pleomorphic rods that do not have endospores, flagella, or typical capsules. In vaginal fluid smears, the Gram reaction may vary from positive to negative (Catlin, 1992). G. vaginalis is viewed in non-crowded areas in a Papanicolaou preparation. Their morphology and staining reactions are affected by the bacteria’s physiological state. Both coccobacilli and longer forms occur in 24 hour cultures of G. vaginalis on blood agar. Their average dimensions are 0.4 by 1.0 to 1.5µm. The cells do not elongate into filaments although they can be up to 2 to 3µm (Catlin, 1992).
Cultures on vaginalis agar exhibited many short gram-negative rods. A medium containing starch showed more pleomorphic, gram-variable, clumped, and beaded cultures. 48 hour cultures of patients’ blood specimens with G. vaginalis were reported as mostly gram-positive (Catlin, 1992). G. vaginalis is beta-hemolytic on media containing human or rabbit blood but not on sheep blood agar. Hemolysis is improved by anaerobic incubation.
Catlin (1992) reports that many different media have been used to isolate G. vaginalis from clinical specimens. The most successful media pos...
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...acteria and mycoplasmas. Additional support for this conclusion was obtained in a study of the grivet monkey as a model for bacteria vaginosis.
Bacteria vaginosis is treated with antibiotic medications (CDC). Metronidazole is commonly used. Metronidazole treatment does not adversely affect lactobacilli so they are able to recolonize the vagina and reduce the risk of late-stage relapse (Catlin, 1992). The cephalosporins available in the late 1970s were not very active against G. vaginalis.
G. vaginalis is still a mystery and is being continuously investigated. Research is being done to identify its causes and pathogenicity. Improved media and methods used for the isolation and identification are beneficial to getting answers. The development of a suitable animal model for bacteria vaginosis is one of the challenging areas for future investigation (Catlin, 1992).