Identification of Gardnerella (Haemophilus) vaginalis

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Abstract
Different tests for the identification of G. vaginalis and for its differentiation from catalase-negative unclassified coryneforms from the vagina were evaluated on over 200 bacterial strains, with special emphasis on optimal test conditions. A presumptive identification of G. vaginalis in the clinical laboratory can be made on the basis of colonial morphology, clear .beta. hemolysis with diffuse edges on human blood bilayer-Tween agar, a negative catalase test and typical cell morphology in the Gram stain. This procedure will correctly identify 90-98% of suspect colonies of G. vaginalis with human blood bilayer-Tween agar as primary isolation medium. Useful additional reactions for the confirmation of G. vaginalis include positive hippurate and starch hydrolysis, positive .alpha.-glucosidase but negative .beta.-glucosidase tests, the production of acid from glucose and maltose but not from mannitol and susceptibility to disks containing metronidazole, nitrofurantoin, sulfonamides and bile.