M. genitalium infection linked to chlamydia, highly antibiotic-resistant

Mycoplasma genitalium infection appears to be prevalent among individuals with chlamydia and shows an alarmingly high level of resistance to the recommended first-line antibiotics on a background of a low rate of screening for such an infection in Singapore, according to a study.

“The strong association of M. genitalium with Chlamydia trachomatis (CT), for which there is more frequent testing, suggests that, at a minimum, patients with CT in Singapore should be screened for M. genitalium,” the investigators said. “Furthermore, treatment of CT, as well as other infections, should be undertaken with due consideration to the high resistance rates of M. genitalium.”

In the current study, the investigators tested 358 urine and 114 urethral swab samples collected from the Department of Sexually Transmitted Infections Control (DSC) Clinic in Singapore for CT or Neisseria gonorrhoeae (NG) infection and for the presence of M. genitalium.

Overall, 185 samples tested positive for either CT, NG or both. M. genitalium infection was found with significantly greater frequency in CT-positive than in CT-negative samples (8.1 percent vs 2.4 percent). This translated to about a threefold increased odds of coinfection with CT and M. genitalium (odds ratio, 3.54, 95 percent confidence interval, 1.26–9.98; p=0.017). Conversely, M. genitalium was not independently linked to NG infection. [BMC Infect Dis 2020;20:314

When M. genitalium strains were screened for genomic mutations associated with antibiotic resistance, results revealed high rates of resistance mutations to both macrolides (25 percent) and fluoroquinolones (37.5 percent), with most strains being dual-resistant. More importantly, the mutations were only detected in strains from samples with CT coinfection.

“The high rate of overall and multidrug resistance follows the global trend of increasing levels of macrolide and fluoroquinolone resistance in M. genitalium,” the investigators noted. [Emerg Infect Dis 2017;23:809-812; BMJ Open 2017;7:e016300; J Antimicrob Chemother 2014;69:2376-2382; PLoS One 2017;12:e0175763]

The present data support the case for close monitoring of antibiotic resistance in M. genitalium in Singapore, as in the rest of the world, according to the investigators. Resistance may be managed by establishing timely diagnosis and providing appropriate treatment.

“[However], M. genitalium is often not part of routine screening or tested for in cases of non-gonococcal urethritis… [W]e believe that the close association of M. genitalium and CT in terms of infection and antibiotic resistance suggests that ensuring adequate diagnosis and treatment of M. genitalium in CT-infected patients may constitute a more cost-effective approach in a situation of finite resources,” they said. [Clin Infect Dis Off Publ Infect Dis Soc Am 2014;58:631-637; Sci Rep 2017;7:16162]

“Furthermore, in light of the high rates of (multidrug) resistance in the M. genitalium noted in this study, we agree with recently published guidelines that … treatment should extend beyond a single dose,” they added. [J Eur Acad Dermatol Venereol 2016;30:1650-1656] 

The present study was limited by the lack of precise demographic details of the cohort, but the investigators explained that it would have consisted of both commercial sex workers (CSWs) and non-CSW patients undergoing CT/NG testing for clinical urethritis. This could potentially result in an overestimation in the prevalence of M. genitalium in the general population in Singapore.

The investigators urged a broader examination of the infection locally and emphasized the importance of availability of novel alternatives to macrolide and fluoroquinolone therapy.