Mycoplasma genitalium #GPCMEsouth

Edward Coughlan is a sexual health physician at Christchurch hospital. He recently spoke at both GPCME south and to the training registrars. His first talk was on Mycoplasma genitalium and had the title “The new black” which reflects the sexual health worlds recent interest and research going on around M. Gen.

So lets start at the very beginning which is apparently a reasonable place to start.

Mycoplasma genitalium was first isolated from men with urethritis in 1980 by – Tully,Talyor-Robinson- Lancet 1981;1:1288-91 (might need to check in a library to find this it’s the building you use to get free wifi) M. Gen. Is very small with 582,970 base pairs  in a circular chromosome,coding for 521 genes. Has no cell wall. But is very adherent to the urinary tract. It has a flask like shape see the photo from 1981 publication and electron microscope images.


Mycoplasma Genitalium flask

This was followed by a lull whilst the technology caught up. Once PCR arrived the studies have shown that  M. Genitalium is a major cause of non-gonococcal urethritis. range is variable from 10-20% depending on population group making it the most common after chlamydia. Currently the gold standard test is nucleic acid amplification technique (NAAT) this can be done from urine or swabs.

Now when I mentioned M. Gen. on Twitter a reasonable number of people thought this was the sexual health physicians making our lives hard or the diagnosis is irrelevant as the treatment is the same.

See discussion:

 But recent studies have looked at this and the 1g stat dose of azithromycin which was shown to be 95% effective in the earlier studies has  dropped to lower than 80% in the last large case series. But more importantly those who don’t respond to the initial 1g dose have a very low cure rate of 30-40% if the azithromycin stat dose is repeated. The results for doxycycline are much worse with higher initial resistance patterns around 70%. The current 1g “Z-Pack” and go approach is selecting for resistant strains of M. Gen.

As recurrent Non-gonococcal non -chlamydial urethritis are the patients most likely to have M. Gen these are the patients we should be testing. So how can you prevent its resistance? using a 500mg stat dose followed by 4 days of 250mg worked well for 95% of patients. Which leaves you with a small group 1 in 20 who are resistant.

So what then? Pharmac has just approved Moxifloxacin special authority for Azithromycin resistant M. Gen. SA funding is for a 7 day course of 400mg daily. This is for NAAT confirmed M. Gen. after failing the long azithromycin course.

In short if you are treating patients for urethritis you should know about M. Gen. If someone has recurrence of their Urethritis then you should be thinking about it and testing and if they have “treatment resistant” Non-gonnococcal non-chlamydial  urethritis M. Gen. should be your first thought.


Wikstrom  STI 2006 82 ;276

Bjornelius STI 2008, 84,72-76


H Sen Yew et al. J Clin Microbiol. 2011 April; 49(4): 1695–1696.