Background
Mycoplasma genitalium (MG) is a common sexually transmitted infection (STI) that causes significant morbidity. The availability of molecular diagnostic tests has begun to improve our understanding of this infection.
The transmission of STI by oral sex is well recognised for chlamydia, gonorrhoea, herpes and syphilis. However, the role of oral sex in MG transmission is considered to be insignificant, as reflected in the current guidelines and clinical practice where the oral swab for MG is not tested.
We report a case of MG transmission by unprotected receptive oral sex in a heterosexual man.
Case report
A 31 year-old man presented with pain on passing urine for 6 weeks and had noticed some penile discharge for 8 weeks. He reported receiving unprotected oral sex from a casual female partner 8 weeks before the onset of symptoms and did not have any vaginal or anal sex. He did not have any other sexual contact since breaking up from his regular female partner 9 months earlier.
There was no previous history of any STIs. He already had negative test results for chlamydia and gonorrhoea on a urine sample in the second week of his symptoms, and had been treated with an extended dose of Azithromycin (2g over 3 days) without much improvement of his symptoms.
The genitourinary examination was unremarkable apart from scanty urethral discharge. Urine dipstick detected leucocytes. Urine tested negative for chlamydia and gonorrhoea but positive for MG by PCR. The patient was treated with moxifloxacin 400 mg daily for 10 days without waiting for the macrolide resistance test result. Dual therapy with doxycycline and azithromycin was not tried as first line therapy due to suspected macrolide resistance.
MG macrolide resistance test demonstrated the presence of macrolide-associated resistance mutation (MRM) at nt2072G in the MG 23S rRNA gene. The patient tolerated moxifloxacin well apart from slight sickness on the first day. Penile discharge and dysuria disappeared on the third day of treatment. MG test of cure at 4 weeks was negative.
Conclusion
This case illustrates a very high probability of MG transmission by receptive oral sex in a heterosexual man. It is important for clinicians to undertake oral swabs for MG where there is suspicion of pharyngeal infection.
