[Question #6334] Differences

16 months ago
Can you please clarify the difference between mycoplasma hominis and mycoplasma genitalium? Are both an STI?  I’m very confused by the information I’m finding. Thank you. 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
16 months ago
Welcome back to the forum. You have me this time, but I reviewed your recent discussions with Dr. Hook and Ms. Warren -- so you'll have experienced all three of us.

First, I have the impression you're delving deeply into the internet as a result of your husband's recent outside sexual events. I'm not sure it's helping you, but perhaps increasing your anxieties and uncertainties about it. So I'll start by saying that neither M. hominis nor M. genitalium are carried in the oral cavity (or extremely rarely), and hence are not known to be acquired by oral sex. The same situation that used to apply to chlamydia, now known to be potentially but rarely acquired by oral sex.

M. hominis is normal in the genital tract; most people test positive. It is shared between sex partners, but so are hundreds (perhaps thousands) of other bacteria that normally inhabit the genital tract. It is not known to ever cause symptoms or important health outcomes, except it sometimes contributes to post-partum infections in women after delivering babies. It is a mystery to me why so many labs include it in routine STI screening tests; it makes no sense. Probably profit motive, mostly.

M genitalium also is a genital tract bacteria, known for many years but difficult to diagnose until the last decade, when accurate tests became available at reasonable cost. As a result of those tests there has been rapid development of knowledge and interest, but understanding is still incomplete. We know for sure it causes symptomatic infections in men, accounting for about 10-15% of cases of nongonococcal urethritis (NGU). There are clues of possible important health problems in women, but the avaiable research data are confusing and conflicting, and so far no serious outcomes have been documented in women.

Although you don't ask about Ureaplasma urealyticum, it is another mycoplasma-class bacteria that is normal in the genital tract and shared between partners. It's in sort of a gray zone:  a small proportion of infections may causes NGU in men, but for the most part it appears to be harmless, like M. hominis. But whenever tests are done for M gen and M hom, usually UU is included. But a positive results usually is meaningless and does not require treatment.

So based on your previous two threads and this one, it seems the only important outcome of your husband's tryst is chlamydia. I trust you also were treated for it (assuming you had sex with him between his exposure and treatment -- otherwise unnecessary). I would encourage you to stop worrying about any other health consequences from that event. In particular, I see no need for either you or your husband to be tested for MG, MH, or UU.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD
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16 months ago
Thank you very much for your thorough reply. It helps clarify. The last months have definitely been a time of anxiety for me, however, this question was somewhat unrelated to that particular issue. My doctor did not seem to understand the current results and from what you’re describing, has perhaps given me incorrect information. 

I was having some vaginal issues. I have had them in times past, so a vaginal swab was ordered to try and determine any vaginitis or Candida. Not specifically looking for any STI. So the result came back positive for Gardnerella, Bacterial Vaginosis  and Mycoplasma Hominis. He explained that the Hominis was a “form” of STI and that we both needed to be treated for it immediately. That it can cause potential problems mostly in female fertility? I have heard of these, but have little to no knowledge. So, based on what you’re saying, there is no need to treat the Hominis or be concerned that my husband has it or that we are “passing” it back and forth? Or be concerned about the effect on fertility?
 
Thanking you again for your help. 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
16 months ago
For the reasons implied above, I respectfully disagree with your doctor about the need to treat your positive MH test result. There is no proved association of it with female infertility. (Older studies may have come to that conclusion, but it has long since been disproved.) 

However, his comments would be accurate about bacterial vaginosis, i.e. a “form” of STI. (Did you maybe mix up what he said about BV and MH?) BV is associated with sexual activity and sometimes apparently acquired from partners, but not necessarily. It’s basically an overgrowth of mostly normal vaginal bacteria, but sometimes Gardnerella vaginalis may be the trigger. OTOH, treating male partners makes no difference in women’s response to treatment or frequency of recurrence following treatment. BV usually is treated with metronidazole for a week, and it’s important to avoid sex (or use condoms) for a couple of weeks.

You might consider printing out this thread as a framework for further discussion with him. Let me know if anything still isn’t clear.
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