Mycoplasma genitalium 2011-2023

Mycoplasma genitalium – Annual report of Prevalence and Antibiotic Resistance, 2011 to 2023

Data from the Danish Microbiology Database

Mycoplasma genitalium (MG) prevalence and macrolide resistance data for this report have been obtained from the Danish Microbiology Database, MiBa, whereas the previous MG overview (report) was exclusively based on studies conducted at SSI and therefore not nationwide. However, with the legislation regarding the notification of infectious diseases from November 1, 2023, MG achieves the same status as chlamydia, making it possible to report annually with data collected from MiBa. This 2023 report presents data from January 2011 (when MiBa was implemented) to December 2023.

Data on quinolone resistance is based on a random selection of samples s submitted for MG analysis. This report includes samples from January 2018 to December 2023, with a maximum of 200 samples per year, building on the MG overview published in 2023. The testing for determining quinolone resistance has not yet been implemented regionally, so MiBa cannot be used for this analysis.

A disease episode is defined by the first positive test result within a 42-day period. Negative episodes are defined within the same time frame, corresponding to the disease definition used in the chlamydia report. The data analysis is based on disease episodes and is thus independent of the number of tests per patient within the disease episode.

Data include demographic factors such as age, gender, and region, as well as positive and negative test results, including the detection of genetic markers for macrolide resistance. For patients with a valid personal identification number (CPR), information on sex, age, municipality code, region, and area are retrieved. In compliance with GDPR, data where fewer than five episodes are observed are not reported. Incidence or positive rates are indicated here. Not all tested individuals have a valid personal identification number, or information about sex, age, or region, so minor differences in positive rates may occur in the following tables.

Prevalence of MG

From 2011 to 2023, 210,096 episodes were tested for MG. In 2023, 41,956 episodes were tested, compared to 6,680 in 2011, Table 1. The number of episodes in 2023 was higher than in previous years, but the positive rate was slightly lower. MG was detected in 4,972 episodes out of 41,956 tested (11.9%), distributed across 1,995 men (positive rate 16.4%) and 2,977 women (positive rate 10%).

Overall, since 2011, the MG positive rate has increased from 6.1% to 11.9% (p-value for trend in logistic regression, p<0.001), with an average MG positive rate of 9.3%.

Age and Gender Distribution of MG Cases

Tables 2a and 2b show the positive rate, divided by age groups and sex, and Tables 3a and 3b show incidence per 100,000 inhabitants, divided by age groups and sex. Most tests are recorded in the 20-24 age group for both sexes, and generally, more women than men are tested in all age groups under 50, Tables 4a and 4b.

Overall, there is an increase in the positive rate for both men and women from 2011 to 2023, Tables 2 and 3. This increase is particularly evident among those aged 15-24, Figure 1. Among men and women, the highest proportion of positive episodes is in the 20-24 age group, with a positive rate of 22.8% for men and 14.9% for women in 2023, whereas the highest positive rate for chlamydia is seen in the 15-19 age group (Chlamydia - Overview of Disease Prevalence 2023).

Generally, the incidence (per 100,000 inhabitants) increased gradually in all age groups for both men and women from 2011 to 2023, most significantly in the 20-24 age group and between 2020 and 2021, Tables 3a and 3b. This is a natural consequence of increased testing activity and positive rates. Among women, a significant increase in both the positive rate (from 3.9% to 10%) and incidence (7 to 101) was observed from 2011 to 2023. In comparison, the positive rate increased from 11.7% to 16.4%, and the incidence increased from 8 to 68 among men in the same period.

In 2023, the highest incidence among women was in 22-year-olds (754 cases per 100,000) and among men in 25-year-olds (406 cases per 100,000), Figure 1. Compared to chlamydia in 2023, the highest incidence among women was in 19-year-olds and among men in 21-year-olds (Chlamydia - Report of Disease Prevalence 2023). For the entire period from 2011 to 2023, the majority of MG cases were recorded in the 15-29 age group, with the largest proportion in this age group in 2022 (77%) and the smallest in 2014 (62%); in 2023 the proportion was 75%. Compared to chlamydia, the proportion of cases in this age group was slightly lower, as it was 84% for chlamydia in 2023, indicating that chlamydia affects a slightly younger age group than MG.

Geographical Distribution of MG Testing

The largest number of tested individuals came from Copenhagen city and surrounding suburbs for both men (test incidence per 100,000 inhabitants in 2023: 1,575 and 509, respectively) and women (3,646 and 1,439, respectively), Tables 4a and 4b. In 2011 and 2012, more than ten times as many women were tested in North Zealand as in 2013. This is primarily due to very high testing activity in gynecological practices. The high testing activity is also reflected in a higher incidence in 2011 among women in this area (14 in 2011 and 3 in 2012), Table 4b.

There has been a significant increase in testing and incidence nationwide since 2011, particularly in the Capital Region, where the incidence increased from 21 in 2011 to 240 in 2023 for men and from 14 to 355 for women, Tables 5a and 5b. The increase in test incidence has been most pronounced after 2020. In comparison, the incidence of laboratory-confirmed chlamydia cases decreased for both men and women from 2022 to 2023 nationwide (Chlamydia - Report of Disease Prevalence 2023).

Treatment and Development of Antibiotic Resistance

The Danish treatment recommendation is based on the European guidelines from IUSTI (International Union against Sexually Transmitted Infections) supported by WHO and ECDC (MG Report of Prevalence and Antibiotic Resistance). Resistance to macrolide and quinolone antibiotics complicates treatment, and the guidelines recommend that treatment of MG infections always be preceded by macrolide resistance testing. Quinolone resistance is not tested unless treatment with moxifloxacin has failed, and quinolone resistance testing is currently only conducted at SSI.

Macrolide Resistance

Since 2011, there has been a significant increase in the macrolide resistance rate regardless of sex, from 40% to approximately 63% (p-value for trend in logistic regression, p<0.0001; Figure 2). Throughout the period, the resistance rate has been comparable between sexes, but the highest rates have been observed in the 15-24 age group for both sexes, Tables 6a and 6b.

Nationally, macrolide resistance rates of up to 70% have been recorded for both sexes in East Jutland and Funen, particularly from 2020 to 2023, except for 2021. The temporarily lower resistance rate in 2021 may be due to reduced use of azithromycin during the COVID-19 pandemic, when azithromycin prescriptions were restricted. Table 7 shows the number of prescriptions (extracted from the Prescription Registry) issued for the treatment of chlamydia and MG from 2019 to 2023. A significant decrease in azithromycin use was observed in 2020 and 2021 compared to 2019, while the use of doxycycline increased significantly during the same period, in accordance with recommendations to change the first-line treatment of uncomplicated chlamydia from azithromycin to doxycycline, effective from 2019.

Quinolone Resistance

Between 2018 and 2023, detection of quinolone resistance-associated mutations (QRAM) was conducted in 1,651 randomly selected MG-positive samples. Figure 3 shows the development of quinolone resistance by sex. Overall, a gradual increase in quinolone resistance was observed for both sexes, from 4.8% in 2018 to 6.3% in 2023 (p-value for trend in logistic regression, p=0.06).

Like macrolide resistance, there is no significant difference in quinolone resistance between men and women, although the rate has been higher among men in the last two years.

During the same period, a significant, though not statistically significant, increase in dual resistance was observed, from 1.6% in 2018 to 5.2% (average dual resistance of 4.8%).
Since the detection of QRAM is a sequencing-based method performed at SSI, it is possible to identify different mutation types. From 2018 to 2023, S83I and D87N were the most frequently observed mutations, which aligns with previous observations from Denmark.

This overview is also discussed in EPI-NEWS 51/2024.