Update in Epidemiology and Management of Mycoplasma genitalium Infections

Semisynthetic Tetramate-Containing Fungal Metabolites with Activity against Trichomonas vaginalis and Mycoplasma genitalium

Tetramic acid-containing natural products are well known for their promising biological activity against various diseases. In our previous study, we reported fungal-derived tetramic acid-containing natural products with activity against Trichomonas vaginalis. Here, we demonstrate that Mycoplasma genitalium is also highly susceptible to this chemotype and we uncovered the initial structure activity relationships on disparate tetramate chemotypes in phomasetin (6) and pyrrolocin A (10). Further, 6 and 10 were modified using "click" chemistry to re-engineer bioactivity. Compounds 6 and 10 hold promise as a pipeline-diversifying chemotype for promising leads against T. vaginalis and M. genitalium.

Prevalence of Mycoplasma genitalium and macrolide resistance in rectal and urine samples among men who have sex with men in Sweden

OBJECTIVES

While Mycoplasma genitalium is reported as a common rectal infection among men who have sex with men (MSM), published data refer predominantly to urethral infections. Currently, most guidelines recommend M. genitalium testing from urine in men with symptomatic, non-gonococcal urethritis. Macrolide resistance-associated mutations (MRMs) among M. genitalium have increased during the last decade especially among MSM. We aim to demonstrate the prevalence and anatomical distribution of M. genitalium infection and MRM in urine and rectal specimens among MSM in Sweden.

METHODS

In this cross-sectional study in 2019, paired urine and rectal samples from symptomatic and asymptomatic MSM attending a sexually transmitted infection clinic in the south of Sweden were screened for M. genitalium, presence of MRM, Neisseria gonorrhoeae, Chlamydia trachomatis, HIV and syphilis.

RESULTS

The overall prevalence of M. genitalium was 10.5% (64 of 609), rectal samples 7.6% (46 of 609) and urine samples 3.9% (24 of 609) (p=0.007). Among M. genitalium-positive cases, single rectal and single urethral infection was detected in 62.5% (40 of 64) and 28.1% (18 of 64), respectively (p<0.0001). Infection at both sites was seen in 9.4% (6 of 64). The prevalence of MRM was 67.9% (19 of 28). M. genitalium was significantly associated with HIV (OR 2.60, 95% CI 1.14 to 5.88, p=0.02). Among the MSM, 7.4% (45 of 609) were infected with N. gonorrhoeae, 6.7% (41 of 609) with C. trachomatis, 7.1% (43 of 609) with HIV and 0.7% (4 of 609) with syphilis.

CONCLUSIONS

In this study, among MSM, most infections with M. genitalium were detected as rectal mono infections. The prevalence of M. genitalium among MSM was almost twofold higher in rectal samples (7.6%) compared with urine samples (3.9%). The prevalence of macrolide resistance was high with no difference between urine and rectal samples.

The fungal natural product fusidic acid demonstrates potent activity against Mycoplasma genitalium

Antimicrobial resistance is extremely common in Mycoplasma genitalium, a frequent cause of urethritis in men and cervicitis, vaginitis, and pelvic inflammatory disease in women. Treatment of M. genitalium infections is difficult due to intrinsic and acquired resistance to many antibiotic classes. We undertook a program to identify novel antimicrobials with activity against M. genitalium from fungal natural products. Extracts of Ramularia coccinea contained a molecule with potent activity that was subsequently identified as fusidic acid, a fusidane-type antibiotic that has been in clinical use for decades outside the United States. We found that minimum inhibitory concentrations of fusidic acid ranged from 0.31 to 4 µg/mL among 17 M. genitalium strains including laboratory-passaged and low-passage clinical isolates. Time-kill data indicate that bactericidal killing occurs when M. genitalium is exposed to ≥10 µg/mL for 48 h, comparing favorably to serum concentrations obtained from typical loading dose regimens. Resistance to fusidic acid was associated with mutations in fusA consistent with the known mechanism of action in which fusidic acid inhibits protein synthesis by binding to elongation factor G. Interestingly, no mutants resistant to >10 µg/mL fusidic acid were obtained and a resistant strain containing a F435Y mutation in FusA was impaired for growth in vitro. These data suggest that fusidic acid may be a promising option for the treatment of M. genitalium infections.

Mycoplasma genitalium membrane lipoprotein induces GAPDH malonylation in urethral epithelial cells to regulate cytokine response

Membrane lipoproteins serve as primary pro-inflammatory virulence factors in Mycoplasma genitalium. Membrane lipoproteins primarily induce inflammatory responses by activating Toll-like Receptor 2 (TLR2); however, the role of the metabolic status of urethral epithelial cells in inflammatory response remains unclear. In this study, we found that treatment of uroepithelial cell lines with M. genitalium membrane lipoprotein induced metabolic reprogramming, characterized by increased aerobic glycolysis, decreased oxidative phosphorylation, and increased production of the metabolic intermediates acetyl-CoA and malonyl-CoA. The metabolic shift induced by membrane lipoproteins is reversible upon blocking MyD88 and TRAM. Malonyl-CoA induces malonylation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and malonylated GAPDH could dissociate from the 3' untranslated region of TNF-α and IFN-γ mRNA. This dissociation greatly reduces the inhibitory effect on the translation of TNF-α and IFN-γ mRNA, thus achieving fine-tuning control over cytokine secretion. These findings suggest that GAPDH malonylation following M. genitalium infection is an important inflammatory signal that plays a crucial role in urogenital inflammatory diseases.

Prevalence and Risk Factors for Antimicrobial Resistance of Mycoplasma genitalium Infections in a High-Risk Population

Background/Objectives:Mycoplasma genitalium (MG) infections and antibiotic resistance are increasing in prevalence while treatment options are limited. Limited data exist regarding MG resistance in Israel. Our aim was to study the prevalence of MG resistance in a sexually transmitted infection (STI) clinic in Israel. Methods: We performed a single-center retrospective study among patients attending an STI clinic during 2019-2020. MG isolates were tested to detect their resistance to azithromycin and fluoroquinolones (FQs) using commercial kits (Allplex™ MG & AziR Assay, Allplex™ MG & MoxiR Assay). We collected patient data regarding the risk factors for STIs and resistance. A multivariate logistic regression model was used to identify the risk factors for resistance. Results: Of the 142 patients who tested positive for MG, 50 (35.2%) and 22 (15.5%) had resistant mutations to azithromycin and FQ, respectively, and 13 (9.2%) showed resistance to both agents. In a multivariate logistic regression model, men who have sex with men (RR 7.01 95% CI 3.00-16.33) and past STIs (RR 2.33 95% CI 1.01-5.34) were independent risk factors for azithromycin resistance. Conclusions: We found a high prevalence of azithromycin resistance and, to a lesser degree, FQ resistance. These findings may help design the treatment guidelines and support routine resistance testing in high-risk populations.

Mycoplasma genitalium's Antibiotic Resistance in Sexually Transmitted Infections Clinics in Israel

OBJECTIVES

To determine the prevalence of antibiotic resistance rate in Mycoplasma genitalium, and distribution of mutations associated with this resistance, among patients that attended sexually transmitted infections (STI) investigation clinics.

MATERIALS AND METHODS

This cross-sectional study included M. genitalium-positive samples (urine, vaginal, rectal, and pharyngeal swabs) collected from 170 patients attending two STI investigation clinics, which were subjected to macrolide and quinolone resistance mutations analyses. Data regarding patient age, sex, and material/anatomical site of testing were collected.

RESULTS

Macrolide-resistance mutations were identified in 48.8% of samples and were more common among males (p < .0001) and in rectal samples (p < .05). A2059C was the most prevalent macrolide-resistance mutation (18.2%). Quinolone resistance was detected in 23% of the samples, with S83I being the most common (17.1%) mutation. Rate of co-resistance to macrolides and quinolones was 21.2%.

CONCLUSIONS

The high rate of antibiotic resistance found in the current study, especially to macrolides, underscores the importance of antibiotic resistance monitoring in M. genitalium isolates in cases of persistent or recurrent urethritis/cervicitis, in cases of treatment failure and among specific populations. Such surveillance will improve treatment regimens and cure rates.

Mycoplasma genitalium: Key Information for the Primary Care Clinician

Mycoplasma genitalium (MG) is an emerging sexually transmitted infection, which appears to be a cause of urethritis and cervicitis and has been associated with pelvic inflammatory disease (PID), epididymitis, proctitis, infertility, complications during pregnancy, and human immunodeficiency virus (HIV) transmission. Three Food and Drug Administration (FDA) approved tests are available. Testing should be focused to avoid inappropriate antibiotic use. The Center of Disease Control and Prevention (CDC) guidelines recommend testing for persistent male urethritis, cervicitis, and proctitis and state that testing should be considered in cases of PID. Testing is also recommended for sexual contacts of patients with MG. Testing is not recommended in asymptomatic patients, including pregnant patients, who do not have a history of MG exposure. Although resistance-guided therapy is recommended, there are currently no FDA approved tests for MG macrolide resistance, and tests are not widely available in the United States. The CDC recommends 2-step treatment with doxycycline followed by azithromycin or moxifloxacin. Moxifloxacin is recommended if resistance testing is unavailable or testing demonstrates macrolide resistance..

Overcoming antibiotic resistance: non-thermal plasma and antibiotics combination inhibits important pathogens

Antibiotic resistance (ATBR) is increasing every year as the overuse of antibiotics (ATBs) and the lack of newly emerging antimicrobial agents lead to an efficient pathogen escape from ATBs action. This trend is alarming and the World Health Organization warned in 2021 that ATBR could become the leading cause of death worldwide by 2050. The development of novel ATBs is not fast enough considering the situation, and alternative strategies are therefore urgently required. One such alternative may be the use of non-thermal plasma (NTP), a well-established antimicrobial agent actively used in a growing number of medical fields. Despite its efficiency, NTP alone is not always sufficient to completely eliminate pathogens. However, NTP combined with ATBs is more potent and evidence has been emerging over the last few years proving this is a robust and highly effective strategy to fight resistant pathogens. This minireview summarizes experimental research addressing the potential of the NTP-ATBs combination, particularly for inhibiting planktonic and biofilm growth and treating infections in mouse models caused by methicillin-resistant Staphylococcus aureus or Pseudomonas aeruginosa. The published studies highlight this combination as a promising solution to emerging ATBR, and further research is therefore highly desirable.

Estimation of antimicrobial resistance of Mycoplasma genitalium, Belgium, 2022

BackgroundAntimicrobial resistance (AMR) of Mycoplasma genitalium (MG) is a growing concern worldwide and surveillance is needed. In Belgium, samples are sent to the National Reference Centre of Sexually Transmitted Infections (NRC-STI) on a voluntary basis and representative or robust national AMR data are lacking.AimWe aimed to estimate the occurrence of resistant MG in Belgium.MethodsBetween July and November 2022, frozen remnants of MG-positive samples from 21 Belgian laboratories were analysed at the NRC-STI. Macrolide and fluoroquinolone resistance-associated mutations (RAMs) were assessed using Sanger sequencing of the 23SrRNA and parC gene. Differences in resistance patterns were correlated with surveillance methodology, socio-demographic and behavioural variables via Fisher's exact test and logistic regression analysis.ResultsOf the 244 MG-positive samples received, 232 could be sequenced for macrolide and fluoroquinolone RAMs. Over half of the sequenced samples (55.2%) were resistant to macrolides. All sequenced samples from men who have sex with men (MSM) (24/24) were macrolide-resistant. Fluoroquinolone RAMs were found in 25.9% of the samples and occurrence did not differ between socio-demographic and sexual behaviour characteristics.ConclusionAlthough limited in sample size, our data suggest no additional benefit of testing MG retrieved from MSM for macrolide resistance in Belgium, when making treatment decisions. The lower occurrence of macrolide resistance in other population groups, combined with emergence of fluoroquinolone RAMs support macrolide-resistance testing in these groups. Continued surveillance of resistance in MG in different population groups will be crucial to confirm our findings and to guide national testing and treatment strategies.

STI pathogens in the oropharynx: update on screening and treatment

PURPOSE OF REVIEW

The rise in antimicrobial resistance in several STI pathogens such as Neisseria gonorrhoeae has become a public health threat as only one first-line treatment remains. Reducing screening interval for gonorrhoea and chlamydia in high-prevalence populations has been proposed to address antimicrobial stewardship, but this remains controversial. This review aimed to revisit the epidemiology of infections at the oropharynx and review the current screening recommendations and treatment guidelines in different populations.

RECENT FINDINGS

Emerging evidence suggests that the oropharynx is the primary anatomical site for gonorrhoea transmission but maybe not for chlamydia transmission. Most international guidelines recommend 3-monthly oropharyngeal gonorrhoea and chlamydia screening for high-prevalence populations (e.g. men who have sex with men) but not low-prevalence populations (e.g. heterosexuals) given the clinical and public health benefits of screening in low-prevalence populations are still unclear. Doxycycline remains the first-line treatment for oropharyngeal chlamydia in most guidelines. However, some countries have moved from dual therapy (ceftriaxone and azithromycin) to monotherapy (ceftriaxone) for oropharyngeal gonorrhoea treatment to address antimicrobial stewardship.

SUMMARY

The transmission of gonorrhoea and chlamydia is still not fully understood. Further work will be required to evaluate the benefits and harms of reducing screening in high-prevalence populations.