Table 3.
Dilution requirements and starting inoculum concentration in flask.
| Organism | %T | Dilution needed after %T dilution | In flask (CFU/mL) | Volume added per flask |
|---|---|---|---|---|
| Lactobacillus gasseri | ∼0.1 | No Dilution Needed | 108 | 20 mL |
| Gardnerella vaginalis | 41–43 | Dilute 1:10 in VDM-PS | 105 | 2 mL |
| Prevotella bivia | 39–41 | Dilute 1:10 in VDM-PS | 105 | 2 mL |
| Escherichia coli | 34–36 | Dilute 1:10 in VDM-PS | 105 | 2 mL |
| Staphylococcus aureus | 15–17 | Dilute 1:100 in VDM-PS | 104 | 2 mL |
| Candida albicans | 0.5–0.8 | Dilute 1:100 in VDM-PS | 104 | 2 mL |
%Transmittance tracker; CFU: Colony forming unit; VDM-PS: Genital tract secretion medium (vaginal defined medium).
The composition of the vaginal defined medium was previously described by Geshnizgani and Onderdonk.41 To enhance the growth and recovery of P. bivia and G. vaginalis,42 the vaginal defined medium was supplemented with peptone by reducing the concentration of dextrose to 1.0 g/L, supplementing with 5.0 g/L peptone and adjusting to pH 6.5 ± 0.2, yielding VDM-PS. Pilot studies confirmed that VDM-PS supported the growth of both the individual organisms and the mixed inoculum under anaerobic conditions (data not shown).