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Sexually Transmitted Diseases: Volume 27(5) May 2000 pp 249-251

Reexamining the Prevalence of Chlamydia trachomatis Infection Among Gay Men With Urethritis: Implications for STD Policy and HIV Prevention Activities


From the *San Francisco Department of Public Health, STD Prevention and Control Services, and the University of California at San Francisco, Departments of Medicine and Laboratory Medicine, San Francisco, California

The authors acknowledge all of the clinicians at San Francisco City Clinic whose dedication and support continue to make important studies such as this one possible.

Reprint requests: Elizabeth L. Ciemins, STD Control Branch, California Department of Health Services, 1947 Center Street, Suite 201, Berkeley, CA 94704.

Received for publication May 26, 1999, revised October 12, 1999, and accepted November 8, 1999.

Abstract TOP

Background: Evidence of an STD-HIV interaction and the availability of noninvasive urine-based screening tests have resulted in an increased focus on chlamydial infections in men.

Goal: To evaluate the prevalence of chlamydial infections among men with urethritis at the San Francisco City Clinic (SFCC).

Study Design: In 1997, male SFCC patients diagnosed with urethritis were tested for chlamydia using urine-based ligase chain reaction and for gonorrhea using urethral culture.

Results: Gonorrhea was identified in 45% of men who have sex with men (MSM) versus 26% of men who have sex with women (MSW). Among men with gonorrhea, chlamydia coinfection was found among 15.2% of MSM and 8.4% of MSW. Among men with nongonococcal urethritis, 18% and 20% of MSM and MSW had chlamydial infection, respectively. Young age was associated with chlamydial infection in MSM.

Conclusion: After a period of low chlamydial infection rates in MSM during the pre-AIDS era, infection rates are increasing among this population. SFCC's revised clinical practice guidelines include chlamydia testing of MSM with urethritis.

DURING THE PAST few decades in San Francisco and throughout the United States, the control of infections caused by Chlamydia trachomatis has been focused on the prevention of the serious complications of untreated infection in women: pelvic inflammatory disease, chronic pelvic pain, ectopic pregnancy, and infertility. Efforts have been centered around the screening of women in the appropriate healthcare settings and the treatment of those identified as infected.

Chlamydial infections in men are not accompanied by the development of serious complications, such as those that are seen in women. Disease in the male has often served as an indicator of a threat to the reproductive health of women. Routine screening of asymptomatic men, however, was not plausible until the recent introduction of noninvasive screening procedures based on the use of urine-based nucleic acid amplification tests. In the absence of a simple screening test, the public health approach to managing chlamydial infections in men was to focus on symptomatic men with urethritis, and to ensure their receipt of effective antichlamydial therapy.

A paucity of current data are available on chlamydial infections in men. In the 1970s, diagnostic surveys of men with urethritis attending sexually transmitted disease (STD) clinics revealed that men who had sex with women (MSW) had higher chlamydial infection rates than did men who had sex with men (MSM). Approximately 5% of MSM and 14% of MSW with urethritis had urethral chlamydial infection, and rates of infection decreased with age.1 Although they were not harboring active infections, MSM in the pre-AIDS era had high levels of antibodies to C trachomatis. Thus, it was assumed that their exposure rates were high, resulting in a relative immunity and subsequent lower active infection rates.1

Similar results were found for coinfections with C trachomatis, which were common among MSW with gonococcal urethritis, with lower coinfection rates discovered in MSM. As a result of recent decreases in sexual risk behavior among MSM in response to the AIDS epidemic, MSM may have less exposure to chlamydia and resultant decreased immunity. Therefore, the current cohort of young MSM may be more susceptible to chlamydial infections.

As a result of the low coinfection rates in MSM, the first Centers for Disease Control and Prevention (CDC) treatment guidelines recommended routine antichlamydial treatment for gonococcal infections only in MSW. No specific consideration for combined therapy for MSM, for whom monotherapy was recommended, was made.2 Current guidelines have, however, been changed to recommend combined therapy for all men, regardless of sexual behavior.

Because chlamydia has not been perceived to be a major problem for MSM and because of low infection rates in the past, MSM have generally received minimal chlamydial-control efforts. In San Francisco, prioritization of resources for chlamydia-prevention activities resulted in the following standards of clinical practice for MSM at the San Francisco City Clinic (SFCC): (1) no chlamydia screening among asymptomatic MSM and; (2) empirical treatment of nongonococcal urethritis (NGU) among MSM, without additional diagnostic testing.

The major impetus behind an increased interest in chlamydial infections in MSM is the substantial evidence that inflammatory STDs increase susceptibility and enhance the transmission of HIV infection.3-7 At SFCC, these findings have prompted a reexamination of chlamydia testing and treatment policies in MSM who are at a high risk of contracting and transmitting HIV infection. The HIV positivity rates at SFCC in 1997 among MSM and MSM injecting drug users (IDUs) were 20.6% and 31.6%, respectively. In addition, among men seeking care at SFCC, gonococcal incidence in MSM is 16,600 per 100,000, compared with 340 per 100,000 among men in the general population. Given these high STD rates and the compelling evidence of an STD-HIV interaction, a reevaluation of the need for broader diagnostic testing and screening was conducted at SFCC. Chlamydia prevalence among MSM with nongonococcal and gonococcal urethritis was measured to assess the need for changes in the current testing protocol.

Methods TOP

San Francisco City Clinic, the city's only municipal STD clinic, provides quality STD services, including diagnosis, treatment, and partner follow-up, for persons 12 years and older. From March 1997 to December 1997, consecutive male patients diagnosed with urethritis at SFCC were tested for C trachomatis using urine-based ligase chain reaction (Abbott Laboratories, Abbott Park, IL). Patients were also tested for gonococcal infection using urethral culture. Urethritis was defined as more than four leukocytes per high-power field on urethral Gram stain. Diagnoses of gonococcal or nongonococcal urethritis were determined. Demographic and behavioral data were also collected including age, race or ethnicity, numbers and types of sex partners, and sexual orientation.

Results TOP

From March 1997 to December 1997, urethritis was identified in 1,080 men at SFCC. Seventy-seven percent (829) of cases were among heterosexuals (MSW), and 23% (251) were among men MSM or with men who have sex with both men and women (MSB). Seventy percent (756) had NGU, and 30% (324) were diagnosed with gonococcal infection. The isolation of Neisseria gonorrhoeae in MSM and MSB was nearly twice that found among MSW (112 of 251 men versus 212 of 829 men; P < 0.001). Among men with gonococcal infection, chlamydia coinfection was also greater in MSM and MSB than MSW (15.2% versus 8.4% men, respectively); however, this difference was not statistically significant. Among men with NGU, 18% of MSM or MSB and 20% of MSW were infected with chlamydia (Tables 1 and 2). Young age was associated with chlamydial infection in MSM or MSB (12 of 41 men younger than 24 years versus 30 of 210 men older than 25 years; P < 0.02).

Table 1

TABLE 1. Men With Urethritis Who Have Sex With Only Men or With Both Men and Women: Proportion in Diagnosis Group by Age and Race/Ethnicity (n = 251)

Table 2

TABLE 2. Men With Urethritis Who Have Sex With Women: Proportion in Diagnosis Group by Age and Race/Ethnicity (n = 829)

Discussion TOP

Chlamydial infections are prevalent in MSM diagnosed with both nongonococcal and gonococcal urethritis at SFCC, and are found at rates similar to those among MSW. Gonococcal and chlamydial coinfection rates ranged from 2.2% among MSW to as high as 15.4% among MSM 20 to 24 years. The similar rates of chlamydial infection and greater rates of coinfection among MSM compared with MSW contrast with results of studies performed during the 1970s in which rates were greater in MSW.1 These earlier studies found coinfection rates of N gonorrhoeae with C trachomatis to be rare among MSM and 15% to 35% among MSW.1 During the late 1970s many MSM had evidence of past chlamydial infection and may have, therefore, developed some resistance to reinfection that would lower the overall prevalence of chlamydia among MSM.1 The current cohort of MSM may be more susceptible to chlamydial infection because they have little resistance from previous infections.

There are certainly other possible explanations for changing chlamydia prevalence over time. Some of the increase in chlamydial infection rates could possibly be attributed to the improved sensitivity of diagnostic tests; however, the observed increase surpasses the level that would likely be attributed to new testing technologies alone. In addition, increased rates would also appear among MSW, and the proportion of rates of infections between MSM and MSW would be maintained. Alternatively, chlamydia rates might be underestimated because of prior antibiotic use among patients. However, data suggest this underestimation to be rare at SFCC and, in any case, overall effects on rates would be minimal. Finally, there may be other unidentified factors potentially contributing to changing rates.

Because of these findings, new clinical practice guidelines were developed at SFCC that included chlamydia testing in MSM with urethritis. This was done to provide timely identification of the etiology of infection and to improve treatment compliance and partner management efforts. Clinical testing increases the effectiveness of prevention and education efforts and improves overall public health surveillance and disease control. Enhanced control of chlamydial infection among MSM could help prevent the continued spread of HIV. In addition, increasing rates of chlamydial infection among symptomatic men may reflect higher rates of infection among asymptomatic men, in whom we are conducting further investigation of chlamydial and gonococcal infections.

References TOP

1. Stamm WE. Chlamydia trachomatis infections of the adult. In: Holmes K, Sparling PF, Lemon S, Stamm WE, Piot P, Wassherheit J, eds. Sexually Transmitted Diseases. San Francisco: McGraw Hill Health Professions Division, 1999:407-422.
2. Centers for Disease Control. Sexually Transmitted Disease Treatment Guidelines. MMWR 1982; 31(2S):38S.
3. Cohen MS, Hoffman IF, Royce RA, et al. Reduction of concentration of HIV-1 in semen after treatment of urethritis: implications for prevention of sexual transmission of HIV-1. Lancet 1997; 349:1868-1873.
4. Darrow WW, Echenberg DF, Jaffe HW, et al. Risk factors for human immunodeficiency virus (HIV) infections in homosexual men. Am J Public Health 1987; 77:479-483.
5. Institute of Medicine. The Hidden Epidemic: Confronting Sexually Transmitted Diseases. Washington, DC: National Academy Press, 1997.
6. Laga M, Alary M, Nzila N, et al. Condom promotion, sexually transmitted diseases treatment, and declining incidence of HIV-1 infection in female Zairian sex workers. Lancet 1994; 344:246-248.
7. Wasserheit JN. Epidemiologic synergy: interrelationships between human immunodeficiency virus infection and other sexually transmitted diseases. Sex Transm Dis 1992; 19:61-65.
© Copyright 2000 American Sexually Transmitted Diseases Association

Citing Articles TOP

Trends in the Prevalence of Pathogens Causing Urethritis in Asturias, Spain, 1989-2000.
Sexually Transmitted Diseases. 30(4):280-283, April 2003.
Prevalence of chlamydia and gonorrhoea among a population of men who have sex with men.
Sexually Transmitted Infections. 78(3):190-193, June 2002.
Cook, R L 1; St George, K 2 3; Silvestre, A J 4; Riddler, S A 1; Lassak, M 3; Rinaldo, C R Jr 4
Intersecting Epidemics and Educable Moments: Sexually Transmitted Disease Risk Assessment and Screening in Men Who Have Sex With Men.
Sexually Transmitted Diseases. 28(8):464-467, August 2001.
Mayer, Kenneth H. MD *; Klausner, Jeffrey D. MD, MPH , + and; Handsfield, H. Hunter MD ++

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