Characterization of Gardnerella vaginalis and G. vaginalis-like organisms from the reproductive tract of the mare

Abstract

Gardnerella vaginalis has been isolated from women with bacterial vaginosis, from the genital tracts of asymptomatic women, and from several other infected body sites in humans. However, until recently, it has not been isolated from any other animal species. Between June 1988 and October 1989, 31 isolates identified as G. vaginalis and 70 isolates identified as G. vaginalis-like organisms have been recovered from the genital tracts of 93 mares from Michigan and Ohio. Identification was based on biochemical reactions, hemolysis on media containing blood from various animal sources, and susceptibility to select antimicrobial agents. This report details the characterization of G. vaginalis and G. vaginalis-like organism isolates obtained from the reproductive tracts of these mares and compares the equine isolates with human isolates.

Acquisition of Iron byGardnerella vaginalis

“…Whether G. vaginalis can utilize the human counterparts of hemin and catalase is not known. The utilization of hemoglobin and hemin derived from equine sources is consistent with the isolation of G. vaginalis from horses (30,66). Also, the utilization of rabbit hemoglobin is consistent with the growth of G. vaginalis in rabbits used in an experimental animal model to study the effects of G. vaginalis infection (16).…”

The aetiology of bacterial vaginosis

“…These bacilli were identified as G. vaginalis by various tests. A larger study that followed investigated the occurrence of G. vaginalis in specimens collected from the genital tracts of 93 mares (Salmon et al. 1991).…”

Gardnerella vaginalis: characteristics, clinical considerations, and controversies.

“…Growth is inhibited on MacConkey agar and Thayer-Martin medium. The foregoing test results for G. vaginalis were compiled from references 56, 81, 174, 227, and 228. Growth inhibition by sodium polyanetholesulfonate or by alpha-hemolytic streptococci was included among tests for the presumptive identification of G. vaginalis in some studies (164,185,198,228), but zone diameters vary under different test conditions (185).…”

“…Efforts to develop an equine model might prove rewarding. Salmon et al (198) detected the presence of Gardnerella strains in the genital flora of mares, the first observation of natural infection in animals. The characteristics used to identify equine isolates as G. vaginalis included the appearance of Gram-stained cells, catalase-negative reaction, hippurate hydrolysis, beta-hemolysis on HBT medium, absence of sheep blood hemolysis, fatty acid profiles, and ultrastructure observed in electron micrographs.…”