Mycoplasma genitalium in non-gonococcal urethritis

Mycoplasma genitalium: An emergent sexually transmitted disease?

This article summarizes the epidemiologic evidence linking Mycoplasma genitalium to sexually transmitted disease syndromes, including male urethritis, and female cervicitis, pelvic inflammatory disease, infertility, and adverse birth outcomes. It discusses the relationship of this bacterium to human immunodeficiency virus infection and reviews the available literature on the efficacy of standard antimicrobial therapies against M genitalium.

Mycoplasma genitalium: should we treat and how?

Mycoplasma genitalium is associated with acute and chronic urethritis in men. Existing data on infection in women are limited and inconsistent but suggest that M. genitalium is associated with urethritis, cervicitis, pelvic inflammatory disease, and possibly female infertility. Data are inconclusive regarding the role of M. genitalium in adverse pregnancy outcomes and ectopic pregnancy. Available data suggest that azithromycin is superior to doxycycline in treating M. genitalium infection. However, azithromycin-resistant infections have been reported in 3 continents, and the proportion of azithromycin-resistant M. genitalium infection is unknown. Moxifloxacin is the only drug that currently seems to uniformly eradicate M. genitalium. Detection of M. genitalium is hampered by the absence of a commercially available diagnostic test. Persons with persistent pelvic inflammatory disease or clinically significant persistent urethritis or cervicitis should be tested for M. genitalium, if possible. Infected persons who have not previously received azithromycin should receive that drug. Persons in whom azithromycin therapy fails should be treated with moxifloxicin.

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 urethritis in men

Mycoplasma genitalium was first isolated from two men with non-gonococcal urethritis (NGU) and thereafter shown to produce urethritis in subhuman primates, inoculated intraurethrally. This mycoplasma has been detected significantly more often in patients with acute NGU, particularly in patients with non-chlamydial NGU, than in subjects without urethritis. The prevalence of M. genitalium-positive non-chlamydial NGU ranges from 18 to 46% of all non-chlamydial NGU cases. In addition, the persistence of M. genitalium in the urethra after antimicrobial chemotherapy is associated with persistence or recurrence of NGU. The various results reported to date tend to support the proposition that M. genitalium is a pathogen of NGU. M. genitalium is highly susceptible to tetracyclines, macrolides, and some new fluoroquinolones, but the clinical data on the chemotherapy in M. genitalium-positive NGU is extremely limited. Because of the possible association between the post-treatment presence of M. genitalium in the urethra and persistent or recurrent NGU, the eradication of this mycoplasma from the urethra is essential in the management of patients with M. genitalium-positive NGU. Further studies are required to establish the optimal chemotherapy for M. genitalium-positive NGU.

Symptomatic urethritis is more prevalent in men infected with Mycoplasma genitalium than with Chlamydia trachomatis

OBJECTIVES

To study the prevalence, symptoms, and signs of Mycoplasma genitalium and Chlamydia trachomatis infections in men attending a Swedish STD clinic and to study the criteria for urethritis.

METHODS

A cross sectional study among STD clinic attendees in Orebro, Sweden. Attendees were examined for microscopic urethritis and first void urine (FVU) was tested for M genitalium and C trachomatis.

RESULTS

The prevalence of M genitalium and C trachomatis was 7% (34/512) and 12% (61/512), respectively. Dual infection was diagnosed in four men. In both infections 90% of the patients had signs of microscopic urethritis. M genitalium positive men had symptomatic urethritis significantly more often than those infected with C trachomatis (73% v 40%, RR 1.8; 95% CI 1.2 to 2.7). 63% of female partners of men infected with M genitalium were infected with M genitalium compared with chlamydial infection in 67% of female partners of men infected with C trachomatis. Non-chlamydial non-gonococcal urethritis without evidence of M genitalium infection was diagnosed in 180 men (35%). Symptoms and/or visible discharge were reported in 49% in this group.

CONCLUSIONS

M genitalium is a common infection associated with symptomatic urethritis and with a high prevalence of infected sexual partners supporting its role as a sexually transmitted infection.

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.

Quantitative detection of Mycoplasma genitalium from first-pass urine of men with urethritis and asymptomatic men by real-time PCR

We developed a TaqMan-based real-time PCR assay for quantifying Mycoplasma genitalium. This assay is able to specifically quantify concentrations of the M. genitalium 16S rRNA gene ranging from 10(7) to 10 copies/reaction. Using the TaqMan assay, we quantified the M. genitalium 16S rRNA gene in first-pass urine of men with urethritis and asymptomatic men who were positive for M. genitalium by PCR- and phylogeny-based assay. Of 130 men with gonococcal urethritis (GU), five were positive for M. genitalium. The mycoplasma load for each specimen was <5 x 10 copies/ml. Of 84 men with chlamydial non-GU (CNGU), seven were positive for M. genitalium. One man had an M. genitalium load of <5 x 10 copies/ml, and six men had loads ranging from 1.1 x 10(7) to 2.7 x 10(2) copies/ml. Of 86 men with nonchlamydial NGU (NCNGU), 17 were positive for M. genitalium. The mycoplasma loads for these men ranged from 3.3 x 10(6) to 2.3 x 10(2) copies/ml. Of 76 asymptomatic men, only two were positive for M. genitalium. For these men, the loads were 2 x 10(2) and <5 x 10 copies/ml. The patients with NGU had significantly higher concentrations of M. genitalium in their first-pass urine than did men with GU (P < 0.01) or asymptomatic men (P < 0.05). In addition, M. genitalium loads were significantly higher in men with NCNGU than those in asymptomatic men (P < 0.05). The quantitative assessment of M. genitalium loads by the TaqMan assay will provide useful information for understanding the pathogenicity of this mycoplasma in the urogenital tract.

Mycoplasma genitalium: another important pathogen of nongonococcal urethritis

PURPOSE

We reviewed findings on the pathogenic role of Mycoplasma genitalium in nongonococcal urethritis and the treatment of men with M. genitalium positive nongonococcal urethritis.

MATERIALS AND METHODS

We reviewed literature selected from peer reviewed journals listed in MEDLINE and from resources cited in those articles from 1967 to January 2001.

RESULTS

M. genitalium was first isolated from 2 men with nongonococcal urethritis and thereafter it was shown to cause urethritis in subhuman primates inoculated intraurethrally. This mycoplasma has been detected significantly more often in patients with acute nongonococcal urethritis, particularly in those with nonchlamydial nongonococcal urethritis, than in those without urethritis. The prevalence of M. genitalium positive nonchlamydial nongonococcal urethritis is 18.4% to 45.5% of all nonchlamydial nongonococcal urethritis cases. In addition, the persistence of M. genitalium in the urethra after antimicrobial chemotherapy is associated with persistent or recurrent nongonococcal urethritis. M. genitalium is highly susceptible to tetracycline, macrolide and some new fluoroquinolones. The regimen of 100 mg. doxycycline orally twice daily for 7 days, which is recommended for chlamydial nongonococcal urethritis, seems to be effective for M. genitalium positive nongonococcal urethritis, although clinical data to substantiate this regimen are limited.

CONCLUSIONS

The various results reported to date tend to support the proposition that M. genitalium is a pathogen of nongonococcal urethritis. However, currently diagnostic methods for this important mycoplasma are not available in clinical practice. Because of the possible association of the posttreatment presence of M. genitalium in the urethra with persistent or recurrent nongonococcal urethritis, eradication of this mycoplasma from the urethra is essential for managing M. genitalium positive disease. However, clinical data on treating M. genitalium positive nongonococcal urethritis are extremely limited. Thus, further studies are required to develop new diagnostic methods that would be available in clinical settings and establish a new treatment algorithm for nongonococcal urethritis, including M. genitalium positive disease.

Association of Mycoplasma genitalium persistence in the urethra with recurrence of nongonococcal urethritis

BACKGROUND

Most patients with recurrent symptomatic nongonococcal urethritis receive negative test results for Chlamydia trachomatis and Ureaplasma urealyticum, and the cause of such recurrence usually is unknown.

GOAL

To assess the association of Mycoplasma genitalium with recurrent nongonococcal urethritis.

STUDY DESIGN

In this study, 72 men with nongonococcal urethritis were treated with levofloxacin. Before and after treatment, symptoms and signs were assessed and first-pass urine was examined for C trachomatis, M genitalium, U urealyticum, and Mycoplasma hominis by polymerase chain reaction-based assays.

RESULTS

In 6 of 45 men who had no symptoms and no evidence of inflammation after treatment, nongonococcal urethritis recurred. Of these 6 men, 5 had positive test results for M genitalium before levofloxacin treatment, which remained positive afterward. After the second treatment for recurrent nongonococcal urethritis, one man was still had a positive test result for the mycoplasma and experienced a subsequent recurrence.

CONCLUSIONS

This study suggests that the persistence of M genitalium in the urethra may be associated with recurrence of nongonococcal urethritis.

Role of Mycoplasma genitalium and Ureaplasma urealyticum in acute and chronic nongonococcal urethritis

One hundred fourteen heterosexual men with acute nongonococcal urethritis (NGU) and 64 patients without NGU were studied. We determined that Chlamydia trachomatis and Mycoplasma genitalium were strongly associated with acute NGU after controlling, by means of multivariate analysis, for age, race, sexual lifestyle, and coinfection (odds ratio [OR], 13.0, 95% confidence interval [CI], 2.6-64.5; and OR, 17.9, 95% CI, 2.0-160, respectively). Eighty-six men with acute NGU reattended at least once 10-92 days after treatment; 59 (69%) of these 86 men had urethritis. Seven men had M. genitalium detected during 10-92 days of follow-up, and all had urethritis. Ureaplasmas were not associated with acute NGU in multivariate analysis, but their detection was associated with the presence of urethritis during follow-up (P=.014). Ureaplasmas or M. genitalium were associated with both chronic NGU, which was defined as urethritis that occurred 30-92 days after the commencement of treatment (P=.028), and chronic NGU with symptoms or signs (P=.005).

The clinical manifestations and treatment of sexually transmitted diseases in human immunodeficiency virus-positive men

Sexually transmitted diseases (STDs) occur commonly in sexually active human immunodeficiency virus (HIV)-positive men. STDs may have atypical presentations, can cause significant morbidity in persons with HIV infection, and may increase the risk of HIV transmission. Thus, the appropriate diagnosis and treatment of STDs in this population are extremely important. The clinical manifestations and treatment of several common STDs in HIV-positive men are reviewed. Further research is needed to define effective management and screening strategies for STDs in men with HIV infection.

Mycoplasma genitalium in non-gonococcal urethritis--a study in Swedish male STD patients

Urethral swab specimens obtained from 101 men attending an STD clinic were examined for the presence of Mycoplasma genitalium by polymerase chain reaction (PCR) amplification. Fifty patients had non-gonococcal urethritis (NGU), and 51 patients were included as controls without urethritis. M. genitalium DNA was detected in 13 (26%) of the urethritis patients and in 5 (10%) of the control patients (P=0.06). No patient positive for M. genitalium had a simultaneous chlamydial infection. Thus, in the 36 patients with non-chlamydial NGU, the prevalence of M. genitalium infection was 36% (P=0.007 compared with controls). All patients with M. genitalium positive urethritis had a high grade urethritis defined as >10 polymorphonuclear cells per high power microscopical field. Compared with the control group, those with M. genitalium positive urethritis had more often had a history of urethritis than had those with chlamydial NGU or those with M. genitalium negative, non-chlamydial NGU.

Mycoplasma genitalium in males with nongonococcal urethritis: prevalence and clinical efficacy of eradication

BACKGROUND

Mycoplasma genitalium is regarded as a potential pathogen of the human urogenital tract based on prevalence findings of several European studies.

GOAL

To determine the prevalence of M genitalium in urethral specimens of symptomatic patients with nongonococcal urethritis and from asymptomatic patients attending a sexually transmitted disease clinic in Milan, and to verify the clinical efficacy of M genitalium eradication by antibiotic treatment.

STUDY DESIGN

From May 1998 to late April 1999, a routine analysis for M genitalium by DNA amplification (polymerase chain reaction) was performed in patients attending the Institute of Dermatological Science in Milan. The authors examined urethral swabs from 178 symptomatic and 23 asymptomatic males. M genitalium-positive patients were clinically and microbiologically tested after treatment with either doxycycline or azithromycin.

RESULTS

Among males with nongonococcal urethritis, M genitalium was detected in 14.0% of patients as the only agent; in 15.1% of patients in association with Chlamydia trachomatis and/or Ureaplasma urealyticum; and in 1 asymptomatic patient. In all symptomatic M genitalium-positive patients, antibiotic treatment eradicated the infection and cured clinical symptoms.

CONCLUSION

These data reveal the high prevalence of M genitalium in symptomatic patients, the rarity of asymptomatic carriers, the high susceptibility to antibiotic treatment, and the clinical efficacy of M genitalium eradication. Moreover, data confirm the etiologic role of M genitalium in inflammatory processes of the human urogenital tract in the Mediterranean area.

Increased frequency of detection of Ureaplasma urealyticum and Mycoplasma genitalium in AIDS patients without urethral symptoms

The roles of Mycoplasma genitalium and Ureaplasma urealyticum in nongonococcal urethritis are not yet well established. The aim of this study was to determine the presence of these microorganisms in the urethral tracts of 187 human immunodeficiency virus type 1 (HIV-1)-infected male patients with no clinical signs of urethritis. The results indicate that the prevalence of M. genitalium and U. urealyticum was higher in AIDS patients than in asymptomatic, HIV-1-infected patients and in healthy individuals. The high rate of mycoplasmas and ureaplasmas detected in AIDS patients, in the absence of urethritis, argues against major roles in causing disease at the urethral mucosal level for these microorganisms.

Etiology of nongonococcal nonchlamydial urethritis

The majority of cases of acute nongonococcal urethritis (NGU) are due to causes other than infection with Chlamydia trachomatis. Pathogens implicated as causes of nonchlamydial nongonococcal urethritis (NCNGU) include Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis, and primary infection with herpes simplex virus. In a majority of cases of acute NCNGU, no pathogen can be isolated. The etiology of chronic NCNGU is unknown.

Detection of Mycoplasma genitalium in patients with urethritis

PURPOSE

We attempted to detect Mycoplasma genitalium in urethral swab specimens by a polymerase chain reaction based assay to determine the prevalence of M. genitalium in patients with urethritis.

MATERIALS AND METHODS

We examined a total of 171 Japanese men who presented to our hospital from February 1995 through January 1997. Of these men 150 had symptoms and signs compatible with acute urethritis and 21 had no symptoms or signs of urethritis. Urethral swab specimens were used to culture Neisseria gonorrhoeae, to detect Chlamydia trachomatis by an enzyme immunoassay and to detect M. genitalium by a polymerase chain reaction based assay.

RESULTS

Gonococcal urethritis was diagnosed in 74 symptomatic men, and nongonococcal urethritis was diagnosed in 76 symptomatic men. Of the 74 cases of gonococcal urethritis 3 (4.1%) were positive for M. genitalium, and 14 (18.9%) were positive for C. trachomatis. Of the 76 cases of nongonococcal urethritis 10 (13.2%) were positive for M. genitalium, and 42 (55.2%) were positive for C. trachomatis. While only 1 of the 42 cases with chlamydial nongonococcal urethritis (2.4%) was positive for M. genitalium, 9 of the 34 chlamydia negative nongonococcal urethritis cases (26.5%) were positive for the mycoplasma. In contrast, all 21 cases men were negative for N. gonorrhoeae, M. genitalium, and C. trachomatis.

CONCLUSIONS

The prevalences of M. genitalium in patients with gonococcal urethritis and nongonococcal urethritis who attended our clinic were 4.1 and 13.2%, respectively. M. genitalium was detected significantly more often in men with nongonococcal urethritis than in asymptomatic men. In addition, its prevalence in men with chlamydia negative nongonococcal urethritis (26.5%) was significantly greater than in those with chlamydia positive nongonococcal urethritis (2.4%). These findings suggest that M. genitalium may be associated with the development of nongonococcal urethritis independent of C. trachomatis.

An association between non-gonococcal urethritis and bacterial vaginosis and the implications for patients and their sexual partners

OBJECTIVES

The aetiology of non-gonococcal urethritis (NGU) in a considerable proportion of men remains unaccounted for. We wished to investigate the possible aetiological role of bacterial vaginosis (BV), the commonest cause of abnormal discharge in women, in this condition.

METHODS

We carried out two studies. In the first, case-control, study, we recruited men with and without NGU and examined their female partners for evidence of BV. The second, cohort design, study which ran concurrently with the first study involved recruiting women with and without BV and examining their male partners for evidence of NGU. The diagnoses of both NGU and BV were made microscopically to include symptomatic and asymptomatic individuals in both disease categories.

RESULTS

In the case-control study 51 couples were recruited. Of these 39 men had NGU and 12 (31%) of their female contacts had BV. In contrast, of 12 men without NGU, only one (8%) of the female partners had BV (odds ratio 4.89, 95% CI: 0.51-42.27). When only Chlamydia trachomatis negative patients were considered, the odds ratio for an association between BV and NGU was increased to 6.77, 95% CI: 0.73-62.68). Thirty eight couples were recruited to the cohort design study. Of 17 women with BV, 12 (71%) of their male partners had NGU. In contrast, of 21 women without BV, seven (33%) of their male partners had NGU (p = 0.049, odds ratio 4.8). When only C trachomatis negative patients were considered, the significance of the association was increased (p = 0.037; odds ratio 5.42).

CONCLUSIONS

An association exists between NGU and BV, and vice versa. If BV arises de novo the findings could help to explain the development of urethritis in stable sexual relationships.

Mycoplasma genitalium in the cervices of Japanese women

BACKGROUND

Mycoplasma genitalium is considered a cause of nongonococcal urethritis in men. This organism also is a cause of genital infections in women, and has been detected in women attending sexually transmitted disease clinics in the United Kingdom and Denmark, although its prevalence is unknown in Japanese women.

GOALS

To determine the prevalence of M. genitalium in the cervices of women with cervicitis or adnexitis as well as in asymptomatic pregnant women in Japan.

STUDY DESIGN

Two hundred women who attended obstetric and gynecologic clinics were recruited. Sixty-four women had cervicitis, 53 had adnexitis, and 3 had both. Eighty pregnant women were asymptomatic for infection. Cervical swab specimens were examined for M. genitalium using a polymerase chain reaction-based assay.

RESULTS

Five (7.8%) of 64 women with cervicitis and 3 (5.7%) of 53 women with adnexitis were positive for M. genitalium. After exclusion of Chlamydia-positive women, 5 (8.8%) of 57 women with cervicitis, and 2 (4.1%) of 49 women with adnexitis were positive for M. genitalium. In none of 80 asymptomatic pregnant women, including a Chlamydia-positive woman, was M. genitalium detected. Overall, 7 (6.6%) of 106 women with Chlamydia-negative genital infections were positive for the M. genitalium. This prevalence was significantly greater than that in asymptomatic pregnant women (P < 0.05).

CONCLUSIONS

A significantly greater prevalence of M. genitalium was demonstrated in Japanese women with Chlamydia-negative cervicitis or adnexitis, compared with that in asymptomatic pregnant women. This study suggests that M. genitalium may play a pathogenic role in a portion of cases with Chlamydia-negative genital infections.

Mycoplasmas: sophisticated, reemerging, and burdened by their notoriety

Mycoplasmas are most unusual self-replicating bacteria, possessing very small genomes, lacking cell wall components, requiring cholesterol for membrane function and growth, using UGA codon for tryptophan, passing through "bacterial-retaining" filters, and displaying genetic economy that requires a strict dependence on the host for nutrients and refuge. In addition, many of the mycoplasmas pathogenic for humans and animals possess extraordinary specialized tip organelles that mediate their intimate interaction with eucaryotic cells. This host-adapted survival is achieved through surface parasitism of target cells, acquisition of essential biosynthetic precursors, and in some cases, subsequent entry and survival intracellularly. Misconceptions concerning the role of mycoplasmas in disease pathogenesis can be directly attributed to their biological subtleties and to fundamental deficits in understanding their virulence capabilities. In this review, we highlight the biology and pathogenesis of these procaryotes and provide new evidence that may lead to increased appreciation of their role as human pathogens.

Failure to detect Mycoplasma fermentans, Mycoplasma penetrans, or Mycoplasma pirum in the urethra of patients with acute nongonococcal urethritis

Urethral swab specimens collected from 108 male Japanese patients with acute nongonococcal urethritis (NGU) and from 50 Japanese men without NGU were examined for the presence of Mycoplasma fermentans, Mycoplasma penetrans, and Mycoplasma pirum by means of polymerase chain reaction-based assays. These mycoplasmas were not detected in any of the specimens, which suggests that they are unlikely to have a pathogenic role in acute NGU.