Researchers study M. genitalium in Montreal

Bacteria called Mycoplasma genitalium (M. genitalium or Mgen) are an emerging sexually transmitted infection (STI). Mgen generally causes symptom-free infection in the urinary tract. However, some people who have this infection can develop urinary problems, including the following:

• discomfort, pain or a burning sensation when urinating
• the need to urinate more frequently than usual
• a sudden need to urinate
• painful intercourse
• painful ejaculation in men
• a discharge from the penis or vagina

These symptoms can be caused by other bacteria, such as those that cause gonorrhea or chlamydia, so a visit to a healthcare provider is necessary to determine the cause of urinary problems.

MG is not commonly diagnosed but it is increasingly being studied, particularly in gay, bisexual and other men who have sex with men (gbMSM).

A team of researchers in Montreal conducted a study called Engage with 716 gbMSM. They collected blood and urine samples as well as swabs of the rectum and throat between November 2018 and November 2019.

The researchers analysed the collected specimens for Mgen and for the bacteria that cause gonorrhea and chlamydia.

Specimens that tested positive for Mgen were further analysed for the presence of genes that are associated with resistance to commonly used antibiotics, such as the following:

• macrolides (such as azithromycin or clarithromycin)
• quinolones (such as ciprofloxacin or moxifloxacin)

Key findings

Overall, about 6% of participants had Mgen—4% in the rectum and 2% in the urine. Only two participants (0.2%) had Mgen in their throat swabs.

Men who had Mgen were likely to:

• be younger than 29 years
• have had six or more sex partners in the past six months

In general, rates of infection with gonorrhea-causing bacteria were relatively low—about 1.5% of the swabs from the rectum or throat tested positive and none of the urine samples were positive.

Rates of infection with the bacteria that cause chlamydia were low in throat swabs (less than 1%) but higher in urine samples (2%) and rectal swabs (3%).

There were 107 men who had HIV and researchers found that they were not at increased risk for Mgen.

Antibiotic resistance

Analysis found that 46 out of 56 specimens (82%) that tested positive for Mgen had genes that are associated with resistance to macrolides; 16 out of 55 specimens (29%; one specimen could not be assessed for other tests) had genes that are associated with resistance to quinolones. A total of 15 specimens had resistance to both classes of antibiotics.

The researchers noted that the rate of resistance to macrolide antibiotics in the present study is higher than previously reported in other studies in Western Canada or Ontario (63%).

The researchers theorized that the high degree of macrolide resistance in Mgen occurred because these antibiotics were used to treat a wide range of STIs in the past.

For the future

The researchers noted that co-infection with Mgen can occur in gbMSM who also have chlamydia or gonorrhea. They encourage healthcare providers to remain “highly vigilant for a possible co-infection in the case of persistent symptoms after adequate treatment [for gonorrhea or chlamydia],” as routine screening for Mgen is not recommended. This is because most cases of Mgen infection are symptom free and exposure to antibiotics may contribute to the further development of resistance.

The researchers stated that the capacity for Mgen testing in Canada is limited. They added that such testing should occur in patients who have persistent or recurrent symptoms suggestive of Mgen infection. In these cases, the recommended treatment is a course of azithromycin; a secondary choice for treatment would be moxifloxacin.

However, recall that the present study found high rates of resistance to azithromycin and that some participants had Mgen that was also resistant to quinolones. Therefore, the researchers called for rapid access to and turnaround of testing for Mgen and assessment of specimens for the presence of resistance to commonly used antibiotics.

The researchers also called for “easier and quicker access” to alternative antibiotics, such as pristinamycin, for the treatment of Mgen. Currently, access to pristinamycin is through Health Canada’s Special Access Program (SAP).

—Sean R. Hosein

REFERENCES:

1. Lê AS, Labbé AC, Foumigue A, et al. Mycoplasma genitalium infection among gay, bisexual and other men who have sex with men in Montreal, Canada. Canada Communicable Disease Report. 2023;49(11/12):477-486.
2. Johnson E, Tieman M, Dumkow K, et al. Comparison of two testing strategies for Mycoplasma genitalium in emergency department patients across a statewide health system. American Journal of Emergency Medicine. 2024 Jan 12; 78:120-126.