Oral Testing

[Gibbs72]

Hello Doctor,

My situation is that I had several one night stands with women recently whilst on a short break from my fiancee which involved cunnilingus. My fiancee and I back together and both of us have recently tested for all STDs, including Mycoplasma Genitalium, privately in the UK and were negative.

However, I am concerned at the risk of passing mycoplasma genitalium to my fiancee that i may have in my mouth through performing cunnilingus on her so plan to have throat swabs carried out as well.  However, I have a couple of questions following reading some posts on this site:

Dr. Hook mentions in a post that throat swabs for Ghonnoreah would only pick up 50% of infections so I'm working on the assumption that the same would apply for m. genitalium throat swabs:

1. Why is this? Is it due to anatomy and swabs not being able to reach the back of the throat? If this is the case then I'm assuming that for those infections that are missed they would be so far toward the back of the throat as not to be possible to pass on through performing cunnilingus anyway?

2. Would the day the swabs carried out make a difference - eg. if you have swabs done on different days are bacteria more 'present' on one day to the next - so for example, you could have one swab one day which wouldn't detect the bacteria and another the day after that might or is the case that if bacteria are there they're there - they don't come and go / move?

3. Would it be the case that if I had 4 swabs done on the same day I'm assuming there would be a much higher chance of detection than just one (given the 50% chance of detection per swab) - this might sound crazy but it would put my mind at rest rather than worrying there was only a 50% chance of detection with one swab.

Thanks Doctor

[H. Hunter Handsfield, M.D.]

There is nothing in that previous thread that implies I would ever suggest oral testing for M genitalium.

1,2) There is no test for M genitalium that has regulatory approval in the US.  I don't know the standards for diagnostic test approval in the UK, or whether the lab used by Freedom Health has reliable data on test performance, especially in the oral cavity.  I'm inclined to doubt it, but you'll have to ask them.

3) Agreed.

4) The 50% performance for gonorrhea throat culture is totally irrelevant.  You cannot transpose test performances between entirely different, unrelated bacteria, with entirely different test technologies.  

Thanks for the thanks. But I think it's time to move on. If you have any further questions, I would recommend you speak with the highly qualified FH experts where your testing was done.

[Gibbs72]

Thanks Doctor. It was actually one of your responses to another post that had got my concerns up (see below) as it seemed to be a complete unknown so I read it as being as much chance as any that MG could infect the oral cavity and you sound much more confident in your response to me above about the low risk.

(http://www.medhelp.org/posts/STDs/Cunnilingus--Mycoplasma-Genitalium/show/1816353)

A couple of follow ups if I may then:

1. Does this mean that a throat swab from a private clinic such as Freedom Health (who you mention in the link above) for Mycoplasma Genitalium would be unapproved?

2. Would an unapproved test potentially mean a strong risk of false positives?

3. To confirm, my reading on your post above about 'not being able to help very much' was wrong and that you are in fact confident that the risk of transmitting cunnlingus to my partner would be minuscule?

4. Just in relation to your response to my point about a 50% chance, this is irrelevant as if we take a throat swab for ghonnoreah as an example the chance of the swab detecting the infection is in fact very high?

Thanks for your clarification Doctor and thanks for an exceptional service.

[H. Hunter Handsfield, M.D.]

Welcome to the forum.

Mycoplasma genitalium is not known to inhabit the oral cavity.  I can't say your risk of getting it from cunnilingus is zero, but I'll bet it's very close to it.  Even if you are exposed, which is statistically unlikely because all STDs are transmitted rarely by cunnilingus, I doubt the infection would take hold in your mouth or throat.  Your worries about it are unfounded.

1) I think you misunderstood something Dr. Hook wrote.  The gonorrhea culture picks up only 50% of throat infections.  The more modern tests (NAAT) pick up almost all infections.  In any case, there is no commercial NAAT or culture for M. genitalium.  If you were tested for it, you can assume it was an unapproved test of uncertain validity.

2,3) I doubt the specific swabs make any difference and would guess that each swab would have an equal chance of picking up any and all pathgens in the throat.  If it's 50% for one swab, I would think it would be the same for all four.  (Whatever the 50% figure means, probalby not much.)

My suggestion is that you drop all concerns about M. gen from the exposur described.  Do not alter your sexual practices with your regular partner and drop any ideas of further testing.

Best wishes-- HHH, MD