Evaluation of liquid culture media to support growth of Mobiluncus species

Mobiluncus curtisii and M. mulieris are anaerobic, gram-negative, motile curved rods isolated commonly from the vagina of women with bacterial vaginosis. Hitherto, there has been difficulty in isolating and growing these bacteria and little attention has been paid to growth in liquid media. Reasons for establishing the means of attaining optimal growth in such media include production of antigens for diagnostic and immunological studies and production of the soluble cytotoxin. In this study the efficacy of 12 liquid culture media in supporting growth was examined. M. mulieris (strain A198) multiplied ≥10-fold in only five media – Schaedler broth, Columbia blood broth (CBB), peptone-starch-dextrose (PSD) broth, brain-heart infusion plus arginine and spent tissue-culture medium. Similarly, M. curtisii (strain A98) multiplied ≥10-fold in only three media – Schaedler broth, CBB and PSD. Some strains of both bacterial species grew very poorly or not at all, in all the media tested. With an inoculum of ≥105/ml, CBB, or PSD plus 10% horse serum, supported the growth of some strains of both bacterial species to 109 organisms/ml within 48 h, and viable bacteria persisted longer in some media (e.g., CBB) than in others. While variation in growth of Mobiluncus spp. may occur between one laboratory and another, these observations provide the basis for optimisation of a universal liquid culture medium that should facilitate production of antigens and cytotoxin.