Cis females generally have a lactobacillus as the primary microflora in the vagina and it's well established that this symbiosis maintains an environment that's resistant to yeast and other infections.

There are enough papers published on trans women to establish that few among us (1 in 30 in one study) have a presence of lactobacilli and both of the studies I've read indicated that while asymptomatic, the median mtf neovagina looks bacterially like bacterial vaginosis in a natal female. It seems pretty clear that this is due to the fact that the inverted skin isn't the equivalent of the natal vaginal walls.

I've read of some post op women douching with yoghurt or other sources of lactobacilli, does anyone here have (good or bad) experiences that might be helpful?

I'm going to say this as delicately as possible, but some encounters with my wife "transferred" stuff from her to me. My GP did run a vaginal flora test out of curiosity a couple years ago (I think?), but all I remember is that he said it was "perfectly normal." So I assume that worked.

I've seen those studies on post-op vaginal flora, and they suffer from the same issue as most studies on trans people - there simply weren't a large number of people being studied. That doesn't mean the studies are *wrong,* necessarily, but it does mean that generalizing to the larger population is less likely to be accurate than when a substantial and representative sample size was achieved.

(Incidentally, the studies also tended to find that trans women who had penetrative sex had a much higher percentage of fecal bacteria in the vagina, which makes sense given the nearness of the structures. So if the study data IS generalizable, a) it may be partly a question of whether other bacteria are arriving to overwhelm a more limited population of "good" bacteria and b) trans women who do not have penetrative sex may be more likely to have cis-normal flora [this could, ahem, explain my results]. At the very least, this implies some suggestions: perhaps careful washing of *all* the relevant parts, including the anus, before and after sex and/or using the supplements shortly thereafter, for one thing.)

Thanks JennaMarie, that's exactly what I was hoping to hear! :-)

There is another approach to this: gather more information. For instance this study from Petrevic et al. 2014 states very clearly that transgender women, even while having been operated with the standard penile inversion technique, have healthy amounts of lactobacilli:

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Lactobacillus species were detected from 47/63 transsexual women (75%). The 279 Lactobacillus signals detected by PCR-DGGE technique belonged to 13 different species. Lactobacilli of the L. delbrueckii group (L. gasseri, L. crispatus, L. johnsonii, L. iners, L. jensenii) were predominant. More than 90% of women harboured a combination of two or more neovaginal Lactobacillus species. In this study we report the frequent occurrence of lactobacilli from neovagina of transsexual women. Both, frequency and composition were similar to the normal lactic acid bacterial microflora in both women of reproductive age and postmenopausal women.

The researchers also went to discuss the earlier findings of the often-cited Weyers et al. study from 2009, in which lactobacilli were found in only one of the 30 test subjects. Petrevic et al. pointed out that the small amount of lactobacilli found were due to the methodology taken. Weyers et al. tried to culture the lactobacilli from pap-smears, a method that isn't as effective. Therefore, Petrevic et al. used a far more sensitive detection method: they used a molecular detection technique, thus negating the need to cultivate the samples. This method (PCR) yielded very different results, as can be seen above.

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In their study of the neovaginal microflora of transsexual women, Weyers et al. isolated lactobacilli in only 1 of 30 transsexual women after culture on 5 different media and through identification of the cultured isolates by tDNA-PCR8. The authors concluded that, although transsexual women have serum oestradiol levels comparable to those of substituted postmenopausal women, the neovaginal environment does not support the growth of lactobacilli. In another report, Weyers et al.9 used microscopic analysis of neovaginal cytology with papanicolaou (PAP) smear and found lactobacilli in 4% of transsexual women. In our study using a molecular detection technique (PCR–DGGE), we verified lactobacilli in 75% of transsexual women. The most important reason for these contradictory data is the different methodologies applied. The lacking reliability of cultural and phenotypic techniqes for the enumeration and species identification obviously constitutes a major problem in characterizing the vaginal Lactobacillus microbiota. Therefore molecular tools are necessary to overcome the drawbacks of the cultural and phenotypical techniques.

Furthermore, you can read more about taking oral supplements in this study:

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60 male to female transsexual women with penile linked neovagina were randomised into two groups. Women in the intervention group (n=33) received oral probiotic capsules and women in the control group (n=27) placebo in for 7 days. Swabs of the neovagina were taken before and after the therapy.
RESULTS:

Comparing the first and second swabs, we observed a significant improvement of the Nugent score in the intervention group 16 (48.5%) vs. low improvement in control group 4 (14.8%) (p<0.006). The neovaginal microflora was significantly enriched with lactobacilli after oral supplementation compared to placebo.

So, there you have it: even with the good ol' penile-inversion technique, attaining normal levels of lactobacilli to keep your vagina healthy and happy is possible, and can be supported by taking oral supplements. In short: nothing to worry about!

Lilifee, thanks!! Not sure how I missed that one, should have looked at papers referring to Weyers. I'd also looked for threads here and few of them were promising so I'm glad I brought it up!