MYCOPLASMA GENITALIUM was isolated in urethral cultures from two men with nongonococcal urethritis (NGU) in 1981,1 and later it was shown to cause urethritis in nonhuman primates.2 A significant association of M. genitalium with acute male NGU has been demonstrated in studies in the United Kingdom3 and Denmark.4 We also examined urethral swab specimens from Japanese men with acute NGU for the presence of M. genitalium, using a polymerase chain reaction (PCR)-based assay. We found a significantly greater prevalence of M. genitalium in men with acute NGU than in asymptomatic men.5
When nonhuman female primates were inoculated intravaginally with M. genitalium, the organism persistently colonized the lower genital tract, and was associated with increased numbers of vaginal polymorphonuclear leukocytes.2,6 A greater than fourfold elevation of the serum antibody specific for M. genitalium was demonstrated in nonhuman primates infected with the mycoplasma. In humans, fourfold or greater increases in titers of the antibody against M. genitalium have also been detected in approximately 40% of women with acute pelvic inflammatory diseases.7M. genitalium has also been demonstrated to have the capacity to attach to human fallopian tube epithelium.8 These findings indicate its pathogenic potential in the genital organs of women. Recently, M. genitalium has been detected in cervical swab specimens from women attending sexually transmitted disease clinics by using a PCR-based assay.9,10 In Japan, however, the prevalence of M. genitalium in women has not been examined. In the current Japanese study, we determined the prevalence of M. genitalium in symptomatic women with cervicitis or adnexitis, or in asymptomatic pregnant women, by examining cervical swab specimens with a PCR-based assay.
Two hundred women, ranging in age from 19 to 49 years (mean age, 29 years), and visiting the obstetric and gynecologic department at Kizawa Memorial Hospital and Hayasaki Ladies Clinic, were recruited. Sixty-four women with a purulent or mucopurulent endocervical discharge or 20 or more polymorphonuclear leukocytes per high-power microscopic field (×1,000) in a cervical smear, were diagnosed as having cervicitis. Fifty-three diagnosed as having adnexitis (salpingitis and oophoritis) had symptoms of abdominal pain and adnexal tenderness, accompanied with fever (>37 °C) and leukocytosis (>8,500/mm3). Three women suffered from both cervicitis and adnexitis. These 120 symptomatic women were not pregnant. Eighty subjects were healthy pregnant women between 27 and 33 weeks of gestation who had no symptoms or signs of genitourinary infection. Two cervical swab specimens were obtained from the 200 subjects. After the endocervical canal had been cleaned by the removal of discharge, a cotton swab was inserted and rubbed against the endocervical canal. A first swab was placed into the DNA probe transport medium for detecting Neisseria gonorrhoeae and Chlamydia trachomatis. A second swab was placed into 0.5 ml of 10 mmol/l Tris-HCl buffer, pH 8.0, including 1 mmol/l EDTA for PCR-based assay to detect M. genitalium. DNA preparation and PCR amplification using a seminested strategy and Southern blot hybridization analysis were performed as previously described.11 Specimens for which the 300-base pair DNA fragment hybridized to the internal probe were regarded as positive for M. genitalium. Gonorrhea was excluded by microscopy or a DNA probe assay (Gen-Probe, San Diego, CA). Prevalence of C. trachomatis also was determined, by testing the cervical swab specimens using a DNA probe assay (Gen-Probe).
The prevalence of M. genitalium in women with cervicitis or adnexitis was compared with that of the mycoplasma in asymptomatic pregnant women. Statistical analysis was conducted by Fisher's exact test. These comparisons were performed as a two-tailed test, with significant set at P < 0.05.
Five (7.8%) of 64 women with cervicitis, 3 (5.7%) of 53 women with adnexitis, and 1 of 3 women with both cervicitis and adnexitis were positive for M. genitalium, respectively (Table 1). In contrast, all 80 asymptomatic pregnant women were negative for the mycoplasma. Nine (7.5%) of 120 women with cervicitis or adnexitis were positive for the mycoplasma. This prevalence was significantly greater than that in asymptomatic pregnant women (P < 0.05). Seven (10.9%) women with cervicitis, four (7.6%) with adnexitis, one with both cervicitis and adnexitis, and one (1.3%) asymptomatic pregnant women were positive for C. trachomatis. One woman with cervicitis and adnexitis, and one woman with adnexitis were positive for both M. genitalium and C. trachomatis. Five (8.8%) of 57 women with Chlamydia-negative cervicitis and 2 (4.1%) of 49 women with Chlamydia-negative adnexitis were positive for M. genitalium. Seven (6.6%) of 106 women with Chlamydia-negative genital infections were positive for the mycoplasma. This prevalence also was significantly greater than that in Chlamydia-negative asymptomatic women (P < 0.05).
In this study, the prevalence of M. genitalium in women with cervicitis was 7.8%, and that of M. genitalium in women with adnexitis, 5.7%. The prevalence of M. genitalium in women with Chlamydia-negative cervicitis was 8.8%, and that of M. genitalium in women with Chlamydia-negative adnexitis, 4.1%. In the United Kingdom, Palmer et al. examined cervical swab specimens for M. genitalium by a seminested PCR-based assay identical to that used in this study, and reported detection of the mycoplasma in 5 (13.2%) of 38 women with cervicitis.9 In Denmark, Jensen et al. detected the mycoplasma using another PCR-based assay in 5 (6.8%) of 74 samples randomly chosen from a group cultured for C. trachomatis.10 On the other hand, the prevalence of M. genitalium in men with Chlamydia-negative NGU has been reported to range from 18% to 35%.3–5 Although the prevalence of M. genitalium in women with Chlamydia-negative cervicitis or adnexitis appeared to be lower, it was still significantly greater for these groups than for Chlamydia-negative asymptomatic pregnant women, suggesting that the mycoplasma might play a pathogenic role in some patients with genital infections. In addition, the presence of M. genitalium in the cervices of women with adnexitis suggests that cervical infection with the mycoplasma might ascend through the endometrium into the upper genital organs.
We are fully aware that this study includes several limitations. The pregnant women without symptoms or signs of cervicitis or adnexitis were referred to as “asymptomatic” subjects. The diagnosis of adnexitis was not based on laparoscopic findings, but only on clinical findings. The DNA probe assay used for the detection of C. trachomatis in this study might underestimate cervical chlamydial infection. Although further studies are needed to establish the pathogenic role of M. genitalium in cervicitis and adnexitis, our study, demonstrating the prevalence of M. genitalium in the cervices of Japanese women, suggests a possible association of this mycoplasma with genital infections in women.
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