To our knowledge, this is the first study to compare the clinical characteristics of women with clinically suspected PID who had genital tract infection due to M. genitalium, N. gonorrhoeae, and/or C. trachomatis. Our study suggests that, as in chlamydial PID, upper genital tract infection due to M. genitalium is less symptomatic than gonococcal PID. However, it should be noted that all women in the PEACH study had clinically suspected PID; therefore, they all presented with some signs or symptoms. Because the inclusion criteria minimized the selection of asymptomatic patients, differences in the clinical characteristics between women with and women without M. genitalium infection may be minimized. It would be important to repeat these analyses in a population that includes women with symptomatic PID and women with subclinical or “silent” PID.
Mucopurulent cervicitis and numerous systemic markers of inflammation, including an elevated oral temperature, elevated WBC count, and elevated erythrocyte sedimentation rate, were more prevalent in women with N. gonorrhoeae infection than in women with only M. genitalium infection. In addition, pelvic pain scores were higher among women with N. gonorrhoeae infection. Women with only N. gonorrhoeae infection had clinical features that were similar to those of women with test results that were positive for both N. gonorrhoeae and M. genitalium. This suggests that, in patients with coinfection, the clinical signs and symptoms of N. gonorrhoeae infection dominate.
The clinical features of women who present with upper genital tract
M. genitalium infection have not been extensively examined. In a study involving 115 women with histologically confirmed endometritis, 100% of women with
M. genitalium infection reported mild abdominal pain, compared with 68% of women without
M. genitalium infection (
P = .06) [
24]. The association of
M. genitalium with diseases of the lower genital tract in women has not been consistently reported, which possibly reflects differences in the population studied and criteria used to assess signs and symptoms at this site. Although some studies have shown an association between
M. genitalium and cervicitis [
9,
25-
27], several PCR studies have failed to find a strong association between symptoms and
M. genitalium lower genital tract infection [
11,
28,
29]. Tosh et al. [
11] conducted a study involving 383 adolescent females who attended a primary care clinic, and they found that women with
M. genitalium identified in the lower genital tract were no more symptomatic than were uninfected women. In a group of women with test results that were negative for both
C. trachomatis and
N. gonorrhoeae, those who had test results that were positive for
M. genitalium were not more likely to have signs (i.e., presence of vaginal erythema, vulvar erythema, or vaginal discharge;
P = .33) or symptoms (i.e., vaginal itching, vaginal burning, and dyspareunia;
P = .35) than were women with test results that were negative for
M. genitalium [
11]. Manhart et al. [
29] also found that lower genital tract
M. genitalium infection was not associated with symptoms. PCR was used to test urine samples obtained from 1714 women who were enrolled in a population-based study, and
M. genitalium infections were not associated with symptoms, because none of the participants who had test results that were positive for
M. genitalium reported experiencing symptoms of vaginal discharge. Conversely, vaginal discharge was more common among women with lower genital tract
M. genitalium infection than it was among women without
M. genitalium infection in a study involving 390 minority women with an active sexually transmitted infection who attended a public health clinic [
30]. The results were similar after controlling for coinfection with other sexually transmitted diseases. However, vaginal discharge was the only genitourinary sign or symptom that was statistically significantly different between women with positive test results and women who were not infected. Casin et al. [
28] found no association between the identification of
M. genitalium in the lower genital tract and urinary symptoms (OR, 1.34; 95% CI, 0.72–2.50) or pelvic pain (OR, 0.93; 95% CI, 0.50–1.73) among women attending a sexually transmitted disease clinic. These PCR studies indicate that
M. genitalium does not produce stronger symptoms in women with lower genital tract infections, compared with symptoms in women without
M. genitalium infection. The limited symptoms induced by
M. genitalium infection are similar to those seen in
C. trachomatis infection [
31].
Our study is unique, in that we compared the clinical characteristics of lower and/or upper genital tract
M. genitalium infection with infections caused by other known bacterial sexually transmitted diseases. In our study, although women with
M. genitalium infection tended to be less symptomatic than women with gonococcal PID, their symptoms were similar to those of women with chlamydial PID. There were no statistically significant differences between women with
M. genitalium infection and women with
C. trachomatis infection with respect to demographic or clinical characteristics. Although no other study has, to our knowledge, compared the clinical characteristics of women with clinically suspected PID, our results are similar to those of a study [
25] conducted among 465 women either attending a sexually transmitted disease clinic or enrolled in a cervical cancer screening program in Sweden that compared the symptoms of
C. trachomatis infection with those of
M. genitalium infection of the lower genital tract. In that study [
25], no statistically significant differences between women with test results positive for
C. trachomatis and those with test results positive for
M. genitalium in the lower genital tract were reported with respect to the presence of symptoms (32% vs. 23%; relative risk, 1.4; 95% CI, 0.6–3.4) or signs (71% vs. 50%; relative risk, 1.4; 95% CI, 0.9–2.3).
Although women with
M. genitalium infection present with fewer clinical signs and symptoms than do women with
N. gonorrhoeae infection, there is evidence from animal and human studies that supports a pathogenic role of
M. genitalium in female upper genital tract infection.
M. genitalium has been found to induce salpingitis in experiments involving monkeys [
32], and it adheres to human fallopian tube epithelial cells in organ culture, resulting in damage to the ciliated cells [
33]. This bacterium can adhere to human spermatozoa, potentially allowing it to be carried to the female upper genital tract on motile sperm [
34].
M. genitalium PID may lead to subsequent reproductive morbidity, including infertility, recurrent PID, and pelvic pain. In a previous analysis of the PEACH data, Haggerty et al. [
35] found that rates of short-term treatment failure (defined as persistent endometritis and pelvic pain after treatment with cefoxitin and doxycycline; found in 41% of patients), infertility (22%), recurrent PID (31%), and chronic pelvic pain (42%) were high among women with test results positive for endometrial
M. genitalium at baseline. These results were similar to those in a subset of women with test results that were negative for
N. gonorrhoeae and
C. trachomatis. Although the association between
M. genitalium and these sequelae did not reach statistical significance, the findings were similar to those previously reported by analyses of the PEACH data, which showed that chlamydial and gonococcal upper genital tract infection was not associated with subsequent morbidity [
36]. This could be explained by the fact that women in the comparison groups who did not have test results positive for
M. genitalium, C. trachomatis, or
N. gonorrhoeae did have signs and symptoms of PID; thus, all women in the PEACH study were at high risk of sequelae, because they had clinically suspected PID.
Infertility after infection with
M. genitalium could result from inflammation and scarring of the fallopian tubes because of frequent PID treatment failure, given that 44% of women with test results positive for
M. genitalium at baseline had positive test results obtained again 30 days after completion of treatment [
35]. A relationship between
M. genitalium and tubal factor infertility has also been identified in serological studies [
37]. Specifically,
M. genitalium antibodies were identified more frequently among women with tubal factor infertility than among women without tubal factor infertility (22% vs. 6%) [
37]. In another serological study, 17% of women with tubal factor infertility had antibodies to
M. genitalium, compared with only 4% of women with healthy fallopian tubes [
38].
The ability to test for concomitant infections due to C. trachomatis, N. gonorrhoeae, and BV was a strength of our study. However, the unavailability of data on other pathogens may limit the interpretation of our findings. It may be possible that specific BV-associated bacteria, anaerobes, and other mycoplasmal bacteria confounded our analysis. However, adjustment for these bacteria was not possible in our current analysis, because only a subset of women in the PEACH study were tested for these bacteria.
In this study, we compared clinical characteristics and signs and symptoms at presentation by microbial etiology among a population of women with clinically suspected PID. As our study suggests, women with
M. genitalium infection may have less symptomatic PID, which, if left untreated, can lead to serious reproductive morbidity, including tubal factor infertility, ectopic pregnancy, chronic pelvic pain, and recurrent PID [
39]. Because the etiology of up to 70% of PID cases is unknown, and because
M. genitalium has frequently been found in women with PID, detection of the pathogen may help to reduce the burden of untreated PID. However, because clinical symptoms may be mild, and because PID is typically diagnosed through clinical suspicion, women with
M. genitalium infection might not seek PID treatment, and cases of
M. genitalium PID might go undiagnosed. Additional studies are needed to determine a diagnostic approach for
M. genitalium PID and to assess the potential reproductive tract sequelae of
M. genitalium upper genital tract infection.