Mycoplasma genitalium: Is It a Sexually Transmitted Pathogen?

Computational identification of putative common genomic drug and vaccine targets in Mycoplasma genitalium

Mycoplasma genitalium is an obligate intracellular bacterium that is responsible for several sexually transmitted infections, including non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women. Here, we applied subtractive genomics and reverse vaccinology approaches for in silico prediction of potential vaccine and drug targets against five strains of M. genitalium. We identified 403 genes shared by all five strains, from which 104 non-host homologous proteins were selected, comprising of 44 exposed/secreted/membrane proteins and 60 cytoplasmic proteins. Based on the essentiality, functionality, and structure-based binding affinity, we finally predicted 19 (14 novel) putative vaccine and 7 (2 novel) candidate drug targets. The docking analysis showed six molecules from the ZINC database as promising drug candidates against the identified targets. Altogether, both vaccine candidates and drug targets identified here may contribute to the future development of therapeutic strategies to control the spread of M. genitalium worldwide.

Emerging patterns of resistance in a cohort of Greek patients with recurrent UTIs: a pilot study

Bacterial urogenital infections caused by multi-drug resistant organisms (MDROs), are increasingly becoming a severe public health issue. The purpose of the present study was to examine the epidemiology of recurrent UTIs along with antimicrobial resistance patterns in a cohort of patients followed as outpatients at an Infectious Disease clinic of a tertiary care center in Greece. One hundred, sequential patients suffering from recurrent UTIs and coming for clinical evaluation, follow-up and treatment were examined; microbiological urine culture results were analyzed. Patients were separated into Group A: patients with ≥3 urogenital infections during the last study year, and Group B: patients with ≤2 urogenital infections. Furthermore, antimicrobial resistance patterns and presence of MDROs in relation to the number of urogenital infections during a three years period was evaluated. Group A had a mean of 4.3 ± 1.7 urogenital infections during the last year of the study, while patients in Group B 1.9 ± 0.3 infections over a three years period. An age cut-off of 30 years was critical for higher UTI rates. Escherichia Coli was the predominant isolated pathogen in 96.2% of the patients. Patients with diabetes mellitus had a 3 fold-higher risk for ≥3 UTIs. Resistance to colistin and imipenem was associated with a history of more than 2 episodes of UTIs but observed in a small number of patients with comorbidities. In this pilot study MDRO detection in patients suffering from recurrent UTIs emphasizes the need for continuous epidemiological surveillance in order to improve our understanding of the evolution of resistance in a common community infection as well as to implement successful prevention strategies.

Cervicitis: Etiology, diagnosis and treatment

Cervicitis is the inflammation of the cervix. It is usually caused by an infectious agent, usually sexually transmitted. Cervicitis is frequently asymptomatic and silent infection can cause complications of the upper genital tract. The symptoms are usually nonspecific, the most significant being an increase in vaginal discharge and/or intermenstrual bleeding. For its diagnosis, there are commercial systems based on molecular techniques that include almost all of the known pathogens associated with cervicitis, although cultures should not be abandoned due to the need to conduct studies of susceptibility to antibiotics. It is recommended to initiate an empirical antibiotic therapy that covers C.trachomatis and N.gonorrhoeae in the case of women at high risk of infection by these pathogens, especially if the follow-up is not assured or adequate diagnostic tests are not available. In women with low risk of sexually transmitted infection, antibiotic therapy should be adjusted to the results of the microbiological results.

Prevalence of Mycoplasma genitalium in different population groups: systematic review andmeta-analysis

BACKGROUND

Mycoplasma genitalium is a common cause of non-gonococcal non-chlamydial urethritis and cervicitis. Testing of asymptomatic populations has been proposed, but prevalence in asymptomatic populations is not well established. We aimed to estimate the prevalence of M. genitalium in the general population, pregnant women, men who have sex with men (MSM), commercial sex workers (CSWs) and clinic-based samples, METHODS: We searched Embase, Medline, IndMED, African Index Medicus and LILACS from 1 January 1991 to 12 July 2016 without language restrictions. We included studies with 500 participants or more. Two reviewers independently screened and selected studies and extracted data. We examined forest plots and conducted random-effects meta-analysis to estimate prevalence, if appropriate. Between-study heterogeneity was examined using the I2 statistic and meta-regression.

RESULTS

Of 3316 screened records, 63 were included. In randomly selected samples from the general population, the summary prevalence was 1.3% (95% CI 1.0% to 1.8%, I2 41.5%, three studies, 9091 people) in countries with higher levels of development and 3.9% (95% CI 2.2 to 6.7, I2 89.2%, three studies, 3809 people) in countries with lower levels. Prevalence was similar in women and men (P=0.47). In clinic based samples, prevalence estimates were higher, except in asymptomatic patients (0.8%, 95% CI 0.4 to 1.4, I2 0.0%, three studies, 2889 people). Summary prevalence estimates were, in the following groups: pregnant women 0.9% (95% CI 0.6% to 1.4%, I2 0%, four studies, 3472 people), MSM in the community 3.2% (95% CI 2.1 to 5.1, I2 78.3%, five studies, 3012 people) and female CSWs in the community 15.9% (95% CI 13.5 to 18.9, I2 79.9%, four studies, 4006 people).

DISCUSSION

This systematic review can inform testing guidelines for M. genitalium. The low estimated prevalence of M. genitalium in the general population, pregnant women and asymptomatic attenders at clinics does not support expansion of testing to these groups.

REGISTRATION NUMBERS

PROSPERO: CRD42015020420.

Mycoplasma genitalium in Women: Current Knowledge and Research Priorities for This Recently Emerged Pathogen

Health consequences of sexually transmitted diseases disproportionately affect women, making it important to determine whether newly emerged pathogens cause sequelae. Although the pathogenic role of Mycoplasma genitalium in male urethritis is clear, fewer studies have been conducted among women to determine its pathogenic role in the female reproductive tract. Pelvic inflammatory disease (PID) is an important cause of infertility and ectopic pregnancy, and Chlamydia trachomatis and Neisseria gonorrhoeae are recognized microbial causes. Emerging data demonstrate an association between M. genitalium and PID, and limited data suggest associations with infertility and preterm birth, yet the attributable risk for female genital tract infections remains to be defined. Further investigations are needed to better define the impact of M. genitalium on women's reproductive health. Importantly, prospective studies evaluating whether screening programs and targeted treatment of M. genitalium improve reproductive outcomes in women are necessary to guide public health policy for this emerging pathogen.

Apparently-Different Clearance Rates from Cohort Studies of Mycoplasma genitalium Are Consistent after Accounting for Incidence of Infection, Recurrent Infection, and Study Design

Mycoplasma genitalium is a potentially major cause of urethritis, cervicitis, pelvic inflammatory disease, infertility, and increased HIV risk. A better understanding of its natural history is crucial to informing control policy. Two extensive cohort studies (students in London, UK; Ugandan sex workers) suggest very different clearance rates; we aimed to understand the reasons and obtain improved estimates by making maximal use of the data from the studies. As M. genitalium is a sexually-transmitted infectious disease, we developed a model for time-to-event analysis that incorporates the processes of (re)infection and clearance, and fitted to data from the two cohort studies to estimate incidence and clearance rates under different scenarios of sexual partnership dynamics and study design (including sample handling and associated test sensitivity). In the London students, the estimated clearance rate is 0.80p.a. (mean duration 15 months), with incidence 1.31%-3.93%p.a. Without adjusting for study design, corresponding estimates from the Ugandan data are 3.44p.a. (mean duration 3.5 months) and 58%p.a. Apparent differences in clearance rates are probably mostly due to lower testing sensitivity in the Uganda study due to differences in sample handling, with 'true' clearance rates being similar, and adjusted incidence in Uganda being 28%p.a. Some differences are perhaps due to the sex workers having more-frequent antibiotic treatment, whilst reinfection within ongoing sexual partnerships might have caused some of the apparently-persistent infection in the London students. More information on partnership dynamics would inform more accurate estimates of natural-history parameters. Detailed studies in men are also required.

Genetic variants of genital mycoplasmas and their relation to the clinical course of inflammatory diseases of the urogenital system in women

Goal of the study. To study genetic variability of M. hominis (based on the vaa gene) and M. genitalium (based on the mg192 gene) derived from biological material samples taken from women with different clinical manifestations of inflammatory diseases of the urogenital system and clinically healthy women (for M. hominis). Materials and methods. Genetic variability of twenty M. hominis samples taken from patients with inflammatory diseases of the urogenital system and twenty M. hominis samples taken from patients without clinical and laboratory signs of inflammatory processes of the urogenital system was studied by the sequence analysis method. Genetic variability of eight M. genitalium samples taken from patients with different clinical signs of inflammatory diseases of the urogenital system was also examined by the sequence analysis method. Results. Three genetic variants of M. hominis based on the vaa gene were found; variant I was revealed more often in patients with clinical manifestations of inflammatory diseases (65.0%), and variant II - in clinically healthy women (60.0%). Three phylogenetic M. gentium groups based on the mg192 gene were revealed; two samples were referred to Groups I and II, and four samples were referred to Group III. Samples from each phylogenetic groups were taken from patients with clinical and laboratory manifestations of cervicitis and urethritis. Conclusion. The study data demonstrate a potential effect of the VAA surface protein on the virulence of opportunistic M. hominis pathogens.

Mycoplasma genitalium infection in women attending a sexually transmitted infection clinic: diagnostic specimen type, coinfections, and predictors

In female sexually transmitted infection clinic attendees, Mycoplasma genitalium was more frequently detected using vaginal (53/73) versus endocervical (43/73) specimens. In women without other sexually transmitted infections, M. genitalium detection (N = 44) was associated with age ≤22 years (odds ratio, 2.53; P = 0.006) and clinical evidence of cervicitis (odds ratio, 2.11; P = 0.03).

Identification of treatment strategies for Mycoplasma genitalium-related urethritis in male patients by culturing and antimicrobial susceptibility testing

Mycoplasma genitalium was first isolated from urethral swab specimens of male patients with non-gonococcal urethritis. However, the isolation of M. genitalium strains from clinical specimens has been difficult. Co-cultivation with Vero cells is one available technique for the isolation of M. genitalium. The strains that can be used for antimicrobial susceptibility testing by broth dilution or agar dilution methods are limited. Macrolides, such as azithromycin (AZM), have the strongest activity against M. genitalium. However, AZM-resistant strains have emerged and spread. Mutations in the 23S rRNA gene contribute to the organism's macrolide resistance, which is similar to the effects of the mutations in macrolide-resistant Mycoplasma pneumoniae. Of the fluoroquinolones, moxifloxacin (MFLX) and sitafloxacin have the strongest activities against M. genitalium, while levofloxacin and ciprofloxacin are not as effective. Some clinical trials on the treatment of M. genitalium-related urethritis are available in the literature. A doxycycline regimen was microbiologically inferior to an AZM regimen. For cases of treatment failure with AZM regimens, MFLX regimens were effective.

Mycoplasma genitalium, an emerging sexually transmitted pathogen

Mycoplasma genitalium is a sexually transmitted organism associated with non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women such as cervicitis, pelvic inflammatory disease, and infertility. There was evidence for an association of M. genitalium with endometritis and pelvic inflammatory disease (PID), but additional studies are necessary to confirm this. The evidence as to whether M. genitalium can cause adverse pregnancy outcomes such as preterm labor is conflicting. But the authors of some studies on M. genitalium as a cause of infertility have reported this association. This species is very difficult to culture; thus, nucleic acid amplification testing is the only method available for M. genitalium detection. The lack of a cell wall makes M. genitalium intrinsically resistant to antibiotics acting at this level, such as beta-lactams. The treatment of M. genitalium infections is not standardized. Macrolides are recommended, especially single-dose azithromycin; tetracyclines are responsible for a great number of therapeutic failures even no resistance mechanism has yet been demonstrated. Acquired resistance to macrolides and fluoroquinolones leading to therapeutic failure has also been reported. All this raises the issue of the most appropriate therapeutic management and requires drafting diagnostic and therapeutic guidelines for the treatment of M. genitalium infections.

Recent perspectives in the diagnosis and evidence-based treatment of Mycoplasma genitalium

Mycoplasma genitalium is a globally important sexually transmitted pathogen. Men infected with M. genitalium frequently present with dysuria, while women may present with or without urogenital symptoms. In some populations, M. genitalium is significantly associated with HIV-1 infection, and is also an etiological agent in pelvic inflammatory disease. However, there is insufficient evidence to establish a causative role of the organism in obstetric complications, including tubal factor infertility. Although several nucleic acid amplification tests offer rapid, sensitive methods for detecting M. genitalium, there is no standardized assay. Available evidence supports treatment of M. genitalium infections with an extended regimen of azithromycin and resistant strains respond to moxifloxacin. Accumulating evidence indicates growing fluoroquinolone resistance, including against moxifloxacin, emphasizing the need for new therapeutic strategies to treat M. genitalium infections.

A comprehensive proteome of Mycoplasma genitalium

Mycoplasma genitalium is a human pathogen associated with several sexually transmitted diseases. Proteomic technologies, along with other methods for global gene expression analysis, play a key role in understanding the mechanisms of bacterial pathogenesis and physiology. The proteome of M. genitalium, model of a minimal cell, has been extended using a combination of different proteomic approaches and technologies. The total proteome of this microorganism has been analyzed using gel-based and gel-free approaches, achieving the identification of 85.3% of the predicted ORFs. In addition, a comprehensive analysis of membrane subproteome has been performed. For this purpose, the TX-114 soluble fraction has been analyzed as well as the surface proteins, using cell-surface protein labeling with CyDye. Finally, the serological response of M. genitalium-infected patients and healthy donors has been analyzed to identify proteins that trigger immunological response. Here, we present the most extensive M. genitalium proteome analysis (85.3% of predicted ORFs), a comprehensive M. genitalium membrane analysis, and a study of the human serological response to M. genitalium.