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Detecting and treating Mycoplasma genitalium

Mycoplasma genitalium (M. genitalium), is thought to affect up to 400,000 Australians.

It causes urethritis in men, and in women it can lead to pelvic inflammatory disease, cervicitis and preterm labour. It is also a recognised cause of anorectal proctitis along with other infections including Chlamydia trachomatis (including the LGV strains), gonorrhoea, syphilis, HSV and shigellosis.

Asymptomatic infection is also common.

Who to test

Only test those with symptoms and their contacts. Screening asymptomatic people for M. genitalium is not currently recommended.

Diagnosis

Females:

PCR on endocervical or vaginal swab, first pass urine (FPU), ThinPrep -collected by cervical brush/swab.

Males:

PCR on urethral swab (in preference to FPU), anorectal swabs.

Throat swabs are not recommended as pharyngeal infection is uncommon.

Transport: Ambient temperature; if there is any delay from collection to transport to the laboratory, the sample must be refrigerated

Current treatment recommendations

Preliminary data from the patient populations suggests resistance rates to macrolides may be as high as 64 per cent.

The highest rates are likely to be in the men who have sex with men (MSM) population. Although information regarding fluoroquinolone resistance (moxifloxacin) is not available with this test, some studies suggest resistance to fluoroquinolones is present in 10–15% of infections.

Doxycycline alone is ineffective in two-thirds of infections but will lower bacterial load in most cases, increasing the likelihood of cure with a subsequent antibiotic.

Pretreating M. genitalium infections with doxycycline for one week and then treating susceptible infections with azithromycin and macrolide-resistant infections with a fluoroquinolone eradicates >90% of infections.

Current treatment regimens

Macrolide sensitive

Doxycycline 100mg bd for seven days followed by azithromycin 1g stat then 500mg daily for three days (total 2.5g)

OR

Doxycycline 100mg bd for seven days followed by azithromycin 1g single dose.

It is not known to what extent the improved outcomes resulting from the use of doxycycline followed by 2.5g azithromycin are due to this dose of azithromycin, rather than simply the pre-treatment with doxycycline.

The higher dose of azithromycin requires a private prescription.

Macrolide resistant

Doxycycline 100mg bd for seven days followed by moxifloxacin 400mg daily for seven days. A longer course of moxifloxacin may be required in women with pelvic inflammatory disease.

Moxifloxacin requires a private prescription, cannot be used in pregnancy and is expensive. It is associated with diarrhoea, occasional tendinopathy and rare neurological and cardiac events.

Treatment failures following appropriate fluoroquinolone treatment may require specialist advice.

Additional actions

Advise no sex without condoms until tested for cure (14 days after completion of treatment).

Advise no sex with untested previous sexual partners.

Test of cure

Test of cure by PCR should be done at least two weeks after treatment is completed i.e. four weeks after commencing therapy.

Contact tracing

In heterosexuals, the risk of PID and reproductive complications suggests a greater need to trace, test and treat infected contacts.

The time period for contact tracing is unknown.

Asymptomatic infection and macrolide resistance are more common in MSM and there is only limited evidence that this is harmful. As moxifloxacin will probably be required for treatment, contact tracing may be best confined to continuing partners of a symptomatic person.

 

References:

Australian STI Management Guidelines for Use in Primary Care

http://www.sti.guidelines.org.au/sexually-transmissible-infections/mycoplasma-genitalium#management

Australian Contact Tracing Manual contacttracing.ashm.org.au/conditions/when-contact-tracing-is-recommended/mycoplasma-genitalium

 

General Practice Pathology is a new regular column each authored by an Australian expert pathologist on a topic of particular relevance and interest to practising GPs.

The authors provide this editorial, free of charge as part of an educational initiative developed and coordinated by Sonic Pathology.