There is incontrovertible evidence that Mycoplasma genitalium is a sexually transmitted pathogen, but the best screening and testing to determine infection, and then the correct treatment, remains a bit uncertain. M. genitalium is hard to study because this bacteria is fastidious in its growing environment, and takes weeks or months to grow each one.
M. genitalium is known to attach to the genital tract cells using a surface adhesion protein, then enters cells, which causes the inflammatory process to commence. M. genitalium can also attach to sperm, allowing increased dispersion into the vaginas and the upper genital tract of women.
In women, M. genitalium can be found in the genital tract, and is found commonly with symptoms and/or those with an infected male partner. The most common findings are cervicitis and urethritis, with fallopian tube inflammation (salpingitis). M. genitalium can be found in women with pelvic inflammatory disease (PID), and in one recorded instance was found in a fallopian tube. There is an association with past infection of M. genitalium and tubal factor infertility.
Diagnosing M. genitalium
There is a clear and urgent need for better testing for M. genitalium. Nucleic acid amplification testing (NAAT) is the only tool we have for detecting M. genitalium. One of the issues is that there may be a low number of the microbes present, so testing needs to be sensitive at this low load level. A cervical swab combined with a urine test in women may be the best approach.
Antibiotic treatments for M. genitalium – hit and miss affair
Varying degrees of success have been observed with antibiotic treatments for M. genitalium, since this bacteria does not have a cell wall, making traditional antibiotics ineffective. Tetracyclines looked promising, but failure rates have turned out to be high. Macrolides (specifically azithromycin) offers the best clearance rates (84 per cent in one study of men). Quinolones like moxifloxacin have good success rates, with ciprofloxacin and ofloxacin less effective. Doxycycline seems to come with a high recurrence rate.
M. genitalium is a slow-growing microbe, thus a longer course of treatment may be indicated – for example one study used azithromycin 1g with an 85 per cent success rate, while a dose of 500mg on day one, followed by 250mg daily for four days eradicated 95 per cent of infections.
Women who present with vaginal discharge, bleeding between periods (metrorrhagia) and pelvic pain may benefit from being tested for M. genitalium.
Best course of action for treating M. genitalium
Symptomatic people who have evidence to suggest that they are infected with M. genitalium are often given first-line therapy of a 5-day course of azithromycin. Single doses of azithromycin are thought to be less effective, however for those who don’t respond to azithromycin, successful treatment may be found with moxifloxacin 400mg daily for 10 days. The risk of antibiotic resistance is high with this treatment, so it should be the second option.