Longitudinal quantitative detection by real-time PCR of Mycoplasma genitalium in first-pass urine of men with recurrent nongonococcal urethritis

Latest Advances in Laboratory Detection of Mycoplasma genitalium

Mycoplasma genitalium is an important sexually transmitted pathogen affecting both men and women. Its extremely slow growth in vitro and very demanding culture requirements necessitate the use of molecular-based diagnostic tests for its detection in clinical specimens. The recent availability of U.S. Food and Drug Administration (FDA)-cleared commercial molecular-based assays has enabled diagnostic testing to become more widely available in the United States and no longer limited to specialized reference laboratories. Advances in the knowledge of the epidemiology and clinical significance of M. genitalium as a human pathogen made possible by the availability of molecular-based testing have led to updated guidelines for diagnostic testing and treatment that have been published in various countries. This review summarizes the importance of M. genitalium as an agent of human disease, explains the necessity of obtaining a microbiological diagnosis, describes currently available diagnostic methods, and discusses how the emergence of antimicrobial resistance has complicated treatment alternatives and influenced the development of diagnostic tests for resistance detection, with an emphasis on developments over the past few years.

Mycoplasma genitalium: A new superbug

Mycoplasma genitalium (MG) is an emerging sexually transmitted pathogen. It is an important cause of nongonococcal urethritis in men and is associated with cervicitis and pelvic inflammatory disease in women, putting them at risk of infertility. Multiple factors that aid pathogenesis of MG include its ability of adhesion, gliding motility, and intracellular invasion by means of the tip organelle. Through intracellular localization and antigenic variation, MG could result in treatment-resistant chronic infection. There are limited data on the prevalence of MG in Indian patients with urogenital syndromes. Recently, a high prevalence of extra genital infection with MG has been reported. Molecular assays are the major diagnostic techniques of MG infection. Antimicrobial agents such as macrolides, along with fluoroquinolones, are the treatment of choice for MG infections. The issue of drug resistance to azithromycin and fluoroquinolones in MG is rising globally. As molecular tests are becoming available for MG, both for the diagnosis and the detection of antimicrobial resistance, any patient with MG infection should then be tested for antimicrobial resistance. Consideration of MG as a cause of sexually transmitted disease in the Indian population is crucial in diagnostic algorithms and treatment strategies. The purpose of this review is to understand the prevalence of MG in different clinical scenarios, molecular mechanisms of pathogenesis, current status of antimicrobial resistance, and its impact on MG treatment.

Retrospective analysis of infection and antimicrobial resistance patterns of Mycoplasma genitalium among pregnant women in the southwestern USA

BACKGROUND

Mycoplasma genitalium is a sexually transmitted infection (STI) pathogen. There have been no published studies concerning symptomatology, prevalence data, antibiotic resistance profiling or reports of co-infection with other STI in pregnant women.

OBJECTIVE

To describe these characteristics among pregnant women attending prenatal clinics in a large tertiary care centre.

DESIGN

Remnant genital samples collected from pregnant women between August 2018 and November 2019 were tested for M. genitalium and Trichomonas vaginalis by the transcription-mediated amplification technique. Specimens with detectable M. genitalium RNA were sequenced for 23S rRNA mutations associated with azithromycin resistance and parC and gyrA mutations associated with resistance to moxifloxacin. Demographic, obstetric and STI co-infection data were recorded.

RESULTS

Of the 719 samples, 41 (5.7 %) were positive for M. genitalium. M. genitalium infection was associated with black race, Hispanic ethnicity and young age (p=0.003, p=0.008 and p=0.004, respectively). M. genitalium infection was also associated with T. vaginalis co-infection and Streptococcus agalactiae (group B Streptococcus) colonisation (p≤0.001 and p=0.002, respectively). Of the 41 positive samples, 26 (63.4%) underwent successful sequencing. Eight (30.8%) had 23S rRNA mutations related to azithromycin resistance. One of 26 (3.8%) positive samples with sequencing results had the gyrA gene mutation and 1 of 18 sequenced samples (5.6%) had the parC gene mutation associated with moxifloxacin resistance.

CONCLUSIONS

Prevalence rates of M. genitalium in pregnant women was 5.7%. M. genitalium infection disproportionately affects young black women co-infected with T. vaginalis. Pregnant women remain at risk for persistent infection with M. genitalium due to decreased azithromycin susceptibility.

Molecular Testing for Mycoplasma genitalium in the United States: Results from the AMES Prospective Multicenter Clinical Study

A prospective multicenter clinical study involving subjects from 21 sites across the United States was conducted to validate the performance of a new in vitro diagnostic nucleic acid amplification test (NAAT) for the detection of Mycoplasma genitalium.

A prospective multicenter clinical study involving subjects from 21 sites across the United States was conducted to validate the performance of a new in vitro diagnostic nucleic acid amplification test (NAAT) for the detection of Mycoplasma genitalium. Seven urogenital specimen types (n = 11,556) obtained from 1,778 females, aged 15 to 74 years, and 1,583 males, aged 16 to 82 years, were tested with the Aptima Mycoplasma genitalium assay, an investigational transcription-mediated amplification (TMA) NAAT for the detection of M. genitalium 16S rRNA. Infected status for enrolled subjects was established using results obtained from testing either self-collected vaginal swab or clinician-collected male urethral swab specimens with a composite reference method consisting of three transcription-mediated amplification NAATs targeting unique regions of M. genitalium 16S or 23S rRNA. M. genitalium prevalence was 10.2% in females and 10.6% in males; prevalence was high in both symptomatic and asymptomatic subjects for both sexes. Compared to the subject infected status standard, the investigational test had sensitivity and specificity estimates, respectively, of 98.9% and 98.5% for subject-collected vaginal swabs, 92.0% and 98.0% for clinician-collected vaginal swabs, 81.5% and 98.3% for endocervical swabs, 77.8% and 99.0% for female urine, and 98.2% and 99.6% for male urethral swabs, 88.4% and 97.8% for self-collected penile meatal swabs, and 90.9% and 99.4% for male urine specimens. For all seven specimen types, within-specimen positive and negative agreements between the investigational test and the composite reference standard ranged from 94.2% to 98.3% and from 98.5 to 99.9%, respectively. These results provide clinical efficacy evidence for the first FDA-cleared NAAT for M. genitalium detection in the United States.

Mollicutes antibiotic resistance profile and presence of genital abnormalities in couples attending an infertility clinic

Objective

Methods

Results

Conclusion

Mycoplasma genitalium: Accurate Diagnosis Is Necessary for Adequate Treatment

Background

Mycoplasma genitalium is very difficult to grow in culture but has been more able to be studied for disease associations since the advent of research molecular amplification assays. Polymerase chain reaction (PCR) and other molecular assays have demonstrated an association with adverse disease outcomes, such as urethritis or nongonococcal urethritis in men and adverse reproductive sequelae in women-for example, cervicitis, endometritis, and pelvic inflammatory disease (PID), including an association with risk for human immunodeficiency virus. The lack of commercially available diagnostic assays has limited widespread routine testing. Increasing reports of high rates of resistance to azithromycin detected in research studies have heightened the need available commercial diagnostic assays as well as standardized methods for detecting resistance markers. This review covers available molecular methods for the diagnosis of M. genitalium and assays to predict the antibiotic susceptibility to azithromycin.

Methods

A PubMed (US National Library of Medicine and National Institutes of Health) search was conducted for literature published between 2000 and 2016, using the search terms Mycoplasma genitalium, M. genitalium, diagnosis, and detection.

Results

Early PCR diagnostic tests focused on the MPa adhesion gene and the 16S ribosomal RNA gene. Subsequently, a transcription-mediated amplification assay targeting ribosomes was developed and widely used to study the epidemiology of M. genitalium. Newer methods have proliferated and include quantitative PCR for organism load, AmpliSens PCR, PCR for the pdhD gene, a PCR-based microarray for multiple sexually transmitted infections, and multiplex PCRs. None yet are cleared by the Food and Drug Administration in the United States, although several assays are CE marked in Europe. As well, many research assays, including PCR, gene sequencing, and melt curve analysis, have been developed to detect the 23S ribosomal RNA gene mutations that confer resistance to azithromycin. One recently developed assay can test for both M. genitalium and azithromycin resistance mutations at the same time.

Conclusions

It is recommended that more commercial assays to both diagnose this organism and guide treatment choices should be developed and made available through regulatory approval. Research is needed to establish the cost-effectiveness of routine M. genitalium testing in symptomatic patients and screening in all individuals at high risk of acquiring and transmitting sexually transmitted infections.

Experimental Infection of Pig-Tailed Macaques (Macaca nemestrina) with Mycoplasma genitalium

Mycoplasma genitalium is an underappreciated cause of human reproductive tract disease, characterized by persistent, often asymptomatic, infection. Building on our previous experiments using a single female pig-tailed macaque as a model for M. genitalium infection (G. E. Wood, S. L. Iverson-Cabral, D. L. Patton, P. K. Cummings, Y. T. Cosgrove Sweeney, and P. A. Totten, Infect Immun 81:2938-2951, 2013, https://doi.org/10.1128/IAI.01322-12), we cervically inoculated eight additional animals, two of which were simultaneously inoculated in salpingeal tissue autotransplanted into abdominal pockets. Viable M. genitalium persisted in the lower genital tract for 8 weeks in three animals, 4 weeks in two, and 1 week in one; two primates resisted infection. In both animals inoculated in salpingeal pockets, viable M. genitalium was recovered for 2 weeks. Recovery of viable M. genitalium from lower genital tract specimens was improved by diluting the specimen in broth and by Vero cell coculture. Ascension to upper reproductive tract tissues was not detected, even among three persistently infected animals. M. genitalium-specific serum antibodies targeting the immunodominant MgpB and MgpC proteins appeared within 1 week in three animals inoculated both cervically and in salpingeal pockets and in one of three persistently infected animals inoculated only in the cervix. M. genitalium-specific IgG, but not IgA, was detected in cervical secretions of serum antibody-positive animals, predominantly against MgpB and MgpC, but was insufficient to clear M. genitalium lower tract infection. Our findings further support female pig-tailed macaques as a model of M. genitalium infection, persistence, and immune evasion.

Management of Mycoplasma genitalium infections - can we hit a moving target?

Mycoplasma genitalium is an etiological agent of sexually transmitted infections, but due to its fastidious growth requirements, only a few M. genitalium strains are available for determination of the activity of currently used and new antimicrobial agents.

Recent clinical trials have demonstrated that treatment with azithromycin has decreasing efficacy due to an increasing prevalence of macrolide resistance, which is likely to be attributed to the widespread use of 1 g single dose azithromycin. Second line treatment with moxifloxacin is similarly under pressure from emerging resistance. The era of single dose monotherapy for uncomplicated STIs such as M. genitalium and N. gonorrhoeae, while convenient for patients and physicians, has been associated with escalating resistance and treatment failure and is now drawing to a close. There is a critical need for trials of combinations of existing registered drugs and new antimicrobial compounds, implementation of diagnostic testing combined with molecular detection of resistance, and antimicrobial surveillance.

Molecular methods for the detection of Mycoplasma and ureaplasma infections in humans: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology

Mycoplasma and Ureaplasma species are well-known human pathogens responsible for a broad array of inflammatory conditions involving the respiratory and urogenital tracts of neonates, children, and adults. Greater attention is being given to these organisms in diagnostic microbiology, largely as a result of improved methods for their laboratory detection, made possible by powerful molecular-based techniques that can be used for primary detection in clinical specimens. For slow-growing species, such as Mycoplasma pneumoniae and Mycoplasma genitalium, molecular-based detection is the only practical means for rapid microbiological diagnosis. Most molecular-based methods used for detection and characterization of conventional bacteria have been applied to these organisms. A complete genome sequence is available for one or more strains of all of the important human pathogens in the Mycoplasma and Ureaplasma genera. Information gained from genome analyses and improvements in efficiency of DNA sequencing are expected to significantly advance the field of molecular detection and genotyping during the next few years. This review provides a summary and critical review of methods suitable for detection and characterization of mycoplasmas and ureaplasmas of humans, with emphasis on molecular genotypic techniques.

Mycoplasma genitalium: an emerging cause of pelvic inflammatory disease

Mycoplasma genitalium is a sexually transmitted pathogen that is increasingly identified among women with pelvic inflammatory disease (PID). Although Chlamydia trachomatis and Neisseria gonorrhoeae frequently cause PID, up to 70% of cases have an unidentified etiology. This paper summarizes evidence linking M. genitalium to PID and its long-term reproductive sequelae. Several PCR studies have demonstrated that M. genitalium is associated with PID, independent of gonococcal and chlamydial infection. Most have been cross-sectional, although one prospective investigation suggested that M. genitalium was associated with over a thirteenfold risk of endometritis. Further, a nested case-control posttermination study demonstrated a sixfold increased risk of PID among M. genitalium positive patients. Whether or not M. genitalium upper genital tract infection results in long-term reproductive morbidity is unclear, although tubal factor infertility patients have been found to have elevated M. genitalium antibodies. Several lines of evidence suggest that M. genitalium is likely resistant to many frequently used PID treatment regimens. Correspondingly, M. genitalium has been associated with treatment failure following cefoxitin and doxycycline treatment for clinically suspected PID. Collectively, strong evidence suggests that M. genitalium is associated with PID. Further study of M. genitalium upper genital tract infection diagnosis, treatment and long-term sequelae is warranted.

Mycoplasma genitalium: from Chrysalis to multicolored butterfly

The history, replication, genetics, characteristics (both biological and physical), and factors involved in the pathogenesis of Mycoplasma genitalium are presented. The latter factors include adhesion, the influence of hormones, motility, possible toxin production, and immunological responses. The preferred site of colonization, together with current detection procedures, mainly by PCR technology, is discussed. The relationships between M. genitalium and various diseases are highlighted. These diseases include acute and chronic nongonococcal urethritis, balanoposthitis, chronic prostatitis, and acute epididymitis in men and urethritis, bacterial vaginosis, vaginitis, cervicitis, pelvic inflammatory disease, and reproductive disease in women. A causative relationship, or otherwise strong association, between several of these diseases and M. genitalium is apparent, and the extent of this, on a subjective basis, is presented; also provided is a comparison between M. genitalium and two other genital tract-orientated mollicutes, namely, Mycoplasma hominis, the first mycoplasma of human origin to be discovered, and Ureaplasma species. Also discussed is the relationship between M. genitalium and infertility and also arthritis in both men and women, as is infection in homosexual and immunodeficient patients. Decreased immunity, as in HIV infections, may enhance mycoplasmal detection and increase disease severity. Finally, aspects of the antimicrobial susceptibility and resistance of M. genitalium, together with the treatment and possible prevention of mycoplasmal disease, are discussed.

Mycoplasma genitalium: an emerging cause of sexually transmitted disease in women

Mycoplasma genitalium is an emerging sexually transmitted pathogen implicated in urethritis in men and several inflammatory reproductive tract syndromes in women including cervicitis, pelvic inflammatory disease (PID), and infertility. This comprehensive review critically examines epidemiologic studies of M. genitalium infections in women with the goal of assessing the associations with reproductive tract disease and enhancing awareness of this emerging pathogen. Over 27,000 women from 48 published reports have been screened for M. genitalium urogenital infection in high- or low-risk populations worldwide with an overall prevalence of 7.3% and 2.0%, respectively. M. genitalium was present in the general population at rates between those of Chlamydia trachomatis and Neisseria gonorrhoeae. Considering more than 20 studies of lower tract inflammation, M. genitalium has been positively associated with urethritis, vaginal discharge, and microscopic signs of cervicitis and/or mucopurulent cervical discharge in seven of 14 studies. A consistent case definition of cervicitis is lacking and will be required for comprehensive understanding of these associations. Importantly, evidence for M. genitalium PID and infertility are quite convincing and indicate that a significant proportion of upper tract inflammation may be attributed to this elusive pathogen. Collectively, M. genitalium is highly prevalent in high- and low-risk populations, and should be considered an etiologic agent of select reproductive tract disease syndromes in women.

Real-time PCR detection of the mg219 gene of unknown function of Mycoplasma genitalium in men with and without non-gonococcal urethritis and their female partners in England

Real-time PCR was employed to detect a region of the Mycoplasma genitalium mg219 gene, a gene of unknown function, in clinical samples. Amplification of DNA and signal production from 15 other species of human mycoplasmas and 14 other bacteria and viruses did not occur. Using a panel of 208 genital and rectal samples, the sensitivity when compared to the modified mgpa gene (encoding the major surface protein MgPa) real-time PCR assay was found to be 100 % and the specificity of the assay 99.5 % with a positive predictive value of 80 % and a negative predictive value of 100 %. The mg219 gene was found to be in all strains of M. genitalium and was highly conserved. M. genitalium was detected in 3.9 % (11/280, 95 % CI 2.1–6.9) of all male specimens, in 7.7 % (10/130, 95 % CI 4.1–13.7) of patients with non-gonococcal urethritis (NGU) and in 0.7 % (1/150, 95 % CI <0.01–4.1) of patients without urethritis. The presence of M. genitalium was significantly associated with NGU (P ≤0.01; 95 % Cl 0.88–0.98) and non-chlamydial-non-gonococcal urethritis (P=0.0005; 95 % Cl 0.84–0.97).

Diagnosis and treatment of pelvic inflammatory disease

Pelvic inflammatory disease (PID), the infection and inflammation of the female upper genital tract, is a common cause of infertility, chronic pain and ectopic pregnancy. Diagnosis and management are challenging, largely resulting from varying signs and symptoms and a polymicrobial etiology that is not fully delineated. Owing to the potential for serious sequelae, a low threshold for diagnosis and treatment is recommended. As PID has a multimicrobial etiology, including Neisseria gonorrhoeae, Chlamydial trachomatis and anaerobic and mycoplasmal bacteria, treatment of PID should consist of a broad spectrum antibiotic regimen. Recent treatment trials have focused on shorter duration regimens, such as azithromycin, and monotherapies including ofloxacin, but data are sparse. Research comparing sequelae development by differing antimicrobial regimens is extremely limited, but will ultimately shape future treatment guidelines.

Specific real-time PCR assays for the detection and quantification of Mycoplasma mycoides subsp. mycoides SC and Mycoplasma capricolum subsp. capripneumoniae

Contagious bovine pleuropneumonia and contagious caprine pleuropneumonia are two severe respiratory infections of ruminants due to infection by Mycoplasma mycoides subsp. mycoides SC (MmmSC) and Mycoplasma capricolum subsp. capripneumoniae (Mccp), respectively. They are included in the OIE list of notifiable diseases. Here we describe the development of rapid, sensitive, and specific real-time PCR assays for the detection and quantification of MmmSC and Mccp DNA. MmmSC PCR primers were designed after whole genome comparisons between the published sequence of MmmSC strain type PG1(T) and the sequence of an M. mycoides subsp. mycoides large colony strain. For Mccp, previously published conventional PCR primers were applied. SYBR green was used as a detection agent for both assays. The assays specifically detected the targeted species in both cultures and clinical samples, and no cross-amplifications were obtained from either heterologous mycoplasma strain cultures or European field samples. The sensitivity of these new assays was estimated at 3-80 colony forming units per reaction and 4-80fg of DNA, representing a 2-3log increase in sensitivity compared to established conventional PCR tests. These new real-time PCR assays will be invaluable for application in various fields such as direct detection in diagnostic laboratories.

Quantitative detection of Ureaplasma parvum (biovar 1) and Ureaplasma urealyticum (biovar 2) in urine specimens from men with and without urethritis by real-time polymerase chain reaction

BACKGROUND

We previously reported a significant association between Ureaplasma urealyticum (biovar 2) and nongonococcal urethritis (NGU). We also found that the presence of Ureaplasma parvum (biovar 1) in the male urethra might be the result of colonization.

OBJECTIVE

The objective of this study was to clarify the pathogenic role of human Ureaplasma in NGU by assessing the association of bacterial loads with clinical findings and inflammatory responses in the urethra.

STUDY DESIGN

The 16S rRNA gene of Ureaplasma was quantified by a TaqMan-based real-time polymerase chain reaction assay in first-pass urine from 37 men with Ureaplasma-positive nonmycoplasmal nonchlamydial NGU (NMNCNGU) and 30 Ureaplasma-positive men without urethritis.

RESULTS

U. urealyticum (biovar 2) loads in 23 men with NMNCNGU were significantly higher than those in 14 men without urethritis. However, U. parvum (biovar 1) loads did not differ significantly between 14 men with NMNCNGU and 20 men without urethritis.

CONCLUSION

The association of increased U. urealyticum (biovar 2) loads with symptomatic urethritis suggests that U. urealyticum (biovar 2) may be a pathogen of NGU. Our results also suggest that the presence of U. parvum (biovar 1) may not be significant in the development of NGU.

System for simultaneous detection of 16 pathogens related to urethritis to diagnose mixed infection

OBJECTIVE

Urethritis is not always caused by a single pathogen, and isolation of more than two pathogens from one patient is not uncommon. We developed a method to simultaneously detect 16 pathogens related to urethritis.

METHODS

We designed specific primers used for amplification of urethritis pathogens in our 16-well microplate assay. Sixteen microliters of each reaction mixture containing template DNA was added to each well to amplify 16 pathogens simultaneously.

RESULTS

After we evaluated the specificity and sensitivity of this microplate polymerase chain reaction method, we used it to detect pathogens in clinical samples. Of 163 clinical samples, 49.7% (81/163) were positive for specific pathogens, and 6.7% (11/163) showed mixed infection. A specific pathogen was not identified in 43.6% (71/163) of cases.

CONCLUSIONS

We developed a 16-well microplate assay with 16 specific primers to identify pathogens associated with urethritis.

Isolation of Mycoplasma genitalium from first-void urine specimens by coculture with Vero cells

Isolation of Mycoplasma genitalium from clinical specimens remains difficult. We describe an improvement of the Vero cell coculture method in which the growth of M. genitalium was monitored by quantitative real-time PCR. Four new M. genitalium strains were isolated from six first-void urine specimens of male Japanese patients with urethritis. In two of them, only M. genitalium was detected: one also contained Ureaplasma urealyticum, and one contained Chlamydia trachomatis, Neisseria gonorrhoeae, U. urealyticum, and Ureaplasma parvum. In the specimens yielding isolates of M. genitalium, growth was documented by quantitative PCR after two to five passages in Vero cells. The complete isolation procedure from the initial inoculation to completion of single-colony cloning took about 1 year. Isolation of M. genitalium from urine specimens proved to be more difficult than from swab specimens. Due to the cytotoxic effect of urine, a procedure involving washing of the urinary sediment was introduced. Furthermore, prolonged storage of the urine specimens before culture was shown to be detrimental to the success of isolation, as shown by the lack of success in attempts to isolate M. genitalium from mailed urine specimens as well as by simulation experiments. High concentrations of penicillin G and amphotericin B were surprisingly inhibitory to the growth of wild-type M. genitalium strains, but penicillin G at 200 IU/ml and polymyxin B at 500 microg/ml could be used as selective antibiotics to avoid bacterial overgrowth in the Vero cell cultures.

Performance of the gen-probe transcription-mediated [corrected] amplification research assay compared to that of a multitarget real-time PCR for Mycoplasma genitalium detection

Mycoplasma genitalium (MG) can cause nongonococcal urethritis and is potentially associated with urethritis, endometritis, and cervicitis. Several assays have been developed to detect MG. Molecular amplification assays for organism detection can be problematic due to the potential for false-positive and false-negative results. Confirmatory testing is often required in these situations, requiring additional time and resources. Use of multigene targets could integrate both detection and verification at lower cost. Utilizing two targets, the MgPa adhesion gene and the 16S rRNA gene, a multitarget real-time (MTRT) PCR for the detection of MG was developed. Samples from patients attending sexually transmitted disease clinics were collected in duplicate. Urine samples from males (n = 286) and self-collected vaginal swabs from females (n = 321) were analyzed by MTRT PCR for MG and the Gen-Probe transcription-mediated [corrected] amplification (TMA) assay, which targets MG rRNA for detection (TMA-MG research use only). Utilizing the criteria of any two targets being positively amplified, the MTRT PCR had a sensitivity and specificity of 91.8% (101 positive samples/110 samples tested) and 99.5% (495/497), respectively, with a positive predictive value (PPV) of 98.1% (101/103) and a negative predictive value (NPV) of 98.2% (495/504). The Gen-Probe TMA-MG assay had a sensitivity, specificity, PPV, and NPV of 98.1% (108/110), 98.1% (488/497), 92.3% (108/117), and 99.5% (488/490), respectively. Comparison between the MTRT PCR and TMA-MG assay by kappa statistic analysis indicated that an overall kappa value was 0.941 (95% confidence interval, 0.907 and 0.976). Both assays demonstrated accuracy in the detection of MG from urine samples from male patients and self-collected vaginal swabs from female patients.

Epidemiology, pathogenesis and treatment of pelvic inflammatory disease

Pelvic inflammatory disease, the infection and inflammation of the female upper genital tract, is a common cause of infertility, chronic pain and ectopic pregnancy. Diagnosis and management are challenging, due largely to a polymicrobial etiology which is not fully delineated. Signs and symptoms of this syndrome vary widely, further complicating diagnosis and treatment. Due to the potential for serious sequelae, a low threshold for diagnosis and treatment is recommended. Since pelvic inflammatory disease has a multimicrobial etiology including Neisseria gonorrhoeae, Chlamydia trachomatis and anaerobic and mycoplasmal bacteria, treatment of pelvic inflammatory disease should be broad spectrum. Recent treatment trials have focused on shorter duration regimens such as azithromycin and monotherapies including ofloxacin, although data are sparse. Research comparing sequelae development by differing antimicrobial regimens is extremely limited, but will ultimately shape future treatment guidelines. Several promising short-duration and monotherapy antibiotic regimens should be evaluated in pelvic inflammatory disease treatment trials for compliance, microbiological and clinical cure, and reduction of subsequent adverse reproductive and gynecological morbidity.

Is Mycoplasma genitalium a Cause of Pelvic Inflammatory Disease?

The evidence for M genitalium as a sexually acquired infection in women is strong, and the organism has been associated with cervicitis and urethritis. In vitro evidence supports the concept that M genitalium causes inflammation in the fallopian tube epithelium, and animal studies have demonstrated the potential for infection to spread from the lower to the upper genital tract. Serologic data in humans who have PID are somewhat conflicting, but studies in infertile women suggest a link between M genitalium and tubal damage. The organism has also been isolated in the endometrium and fallopian tubes of women who have PID. The evidence is therefore accumulating that M genitalium is a cause of PID, and the assessment of reliable tests to further investigate the importance of this organism and its relevance in designing future treatment strategies is urgently needed.

Detection of Mycoplasma genitalium in urogenital specimens by real-time PCR and by conventional PCR assay

A real-time LightCycler PCR (LC-PCR) with hybridization probes for detection of Mycoplasma genitalium in endocervical and first void urine specimens was developed and compared to a conventional PCR. The primers for both assays were identical and designed to amplify a 427 bp fragment of the 16S rRNA gene of M. genitalium. The LC-PCR assay had a detection limit of < 5 bacterial genomes per reaction when dilutions of genomic DNA from a type strain of M. genitalium were tested. First void urine from 398 men and first void urine and endocervical specimens from 301 women attending an STD clinic were analysed by LC-PCR and by the conventional PCR. Using the conventional PCR as reference, the LC-PCR had a specificity of 99.7 % and a sensitivity of 72.2 % for the detection of M. genitalium in first void urine samples from men. There was no significant difference in the performance of the LC-PCR assay compared to the conventional PCR when endocervical swabs were considered (58 and 65 %, respectively) or with a set of endocervical swab/urine specimens for which the LC-PCR assay detected 73 % of the infections (specificity = 98.6 % and sensitivity = 68.2 %) while the conventional PCR detected 85 % of the infections. With female urine specimens there was a significant difference between the two assays (38 and 73 %, respectively; P = 0.01 McNemar's test). This illustrates the need to analyse both endocervical and urine specimens, because M. genitalium DNA was detected in only one of the two specimens in a great number of the M. genitalium-infected women. The lower sensitivity of the LC-PCR assay was probably caused by a combination of inhibition and limitations regarding the amount of template DNA. The LC-PCR assay was easy to perform and the simultaneous amplification and detection eliminated the need for further handling of PCR products. With improvement in sample preparation methods and increased volumes of the template DNA, the LC-PCR assay could be a useful routine diagnostic method.

Mycoplasma genitalium: the aetiological agent of urethritis and other sexually transmitted diseases

Mycoplasma genitalium was first isolated in 1980 from two of 13 men with non-gonococcal urethritis (NGU). It shares several features with M. pneumoniae, a recognized respiratory tract pathogen. It is extremely difficult to isolate by culture. The development of sensitive and specific polymerase chain reaction (PCR) assays in the early 1990s made clinical studies possible and a significant number of publications have shown a strong association between M. genitalium and NGU, independent of Chlamydia trachomatis. The purpose of this review is to evaluate the currently available information on the associations between M. genitalium and urogenital tract infections in men and women and assess their fulfilment of the Henle-Koch postulates. It is concluded that there is very strong evidence that M. genitalium is a cause of NGU in men and cervicitis in women. Evidence for upper genital tract infections in women has begun to accrue, but further studies are needed. The optimal treatment of M. genitalium infections remains to be determined, but antibiotics of the macrolide group appear to be more active than tetracyclines.

Association of Ureaplasma urealyticum (biovar 2) with nongonococcal urethritis

BACKGROUND

The tiny (T)-strain mycoplasmas, designated in 1974 as Ureaplasma urealyticum, have been divided into 2 species, Ureaplasma parvum (biovar 1) and U. urealyticum (biovar 2), but association of each of these species with nongonococcal urethritis (NGU) remains unclear.

GOAL

The goal of this study was to determine whether U. parvum (biovar 1) or U. urealyticum (biovar 2) is associated with NGU.

STUDY DESIGN

The prevalences of U. parvum (biovar 1) and U. urealyticum (biovar 2) in 572 patients with urethritis were compared with those in 141 men without urethritis.

RESULTS

The prevalence of U. urealyticum (biovar 2) in men with NGU (15.8%) or with nonchlamydial NGU (18.0%) was significantly higher than that in men without urethritis (7.8%). The prevalence of U. parvum (biovar 1) in men with NGU (8.5%) or with nonchlamydial NGU (11.1%) did not differ significantly from that in men without urethritis (13.5%).

CONCLUSION

Our results showed a significant association between U. urealyticum (biovar 2) and NGU. They also suggest that the presence of U. parvum (biovar 1) in the male urethra might be the result of colonization.

Use of TaqMan 5' nuclease real-time PCR for quantitative detection of Mycoplasma genitalium DNA in males with and without urethritis who were attendees at a sexually transmitted disease clinic

Mycoplasma genitalium is a cause of nongonococcal urethritis, particularly in patients not infected with Chlamydia trachomatis. A quantitative 5' nuclease assay (TaqMan PCR) was developed and validated. The assay detected a fragment of the MgPa adhesin gene by use of a TaqMan MGB (minor groove binder) probe and included an internal processing control to detect PCR inhibition. Urethral swab specimens and first-void urine samples from M. genitalium-positive men were examined, and the M. genitalium DNA load was correlated to symptoms and signs. The assay consistently detected <5 genome copies without cross-reactions with other mycoplasmas. Urine and urethral swab specimens from men with urethritis had higher M. genitalium DNA loads than specimens from men without urethritis. However, a very broad overlap of DNA loads between patients with and without urethritis was observed. Urethral swab specimens from patients with urethral discharge had a significantly higher DNA load than specimens from patients without discharge. This correlation was not found in first-void urine specimens.