Prevention for Positives

Case 3: Discussion

Rationale for STD Screening in HIV-Infected Persons

Although many HIV-infected individuals consistently practice safe sex, a significant proportion engage in high-risk sexual behaviors, placing themselves at risk for sexually transmitted diseases (STDs).Indeed, HIV-infected persons are more likely than the general population to develop a STD, and some STDs may have atypical presentations or cause significant morbidity in HIV-infected individuals[1]. Promptly identifying and treating STDs can both limit a patient's long-term sequelae from these infections and prevent them from transmitting STDs to their sexual partners.Furthermore, available data suggest the presence of an STD in an HIV-infected person increases the likelihood of transmitting HIV to their sexual partners; for more detailed information regarding this issue, see STDs and HIV Transmission in this same Prevention for Positives Module[2,3]. Thus, prompt treatment of STDs in HIV-infected individuals may reduce their risk of transmitting HIV to others[4]. Finally, detecting a new STD in an HIV-infected patient indicates ongoing high-risk behavior and should prompt an appropriate intervention to eliminate or minimize this high-risk behavior.As part of the initiative for incorporating HIV prevention into the medical care of persons living with HIV, the Centers for Disease Control and Prevention (CDC), Health Resources Services Administration (HRSA), and HIV Medicine Association (HIVMA) strongly emphasize routine periodic STD screening in HIV-infected individuals[5,6].

Incidence and Prevalence of STDs Among HIV-Infected Individuals

The overall incidence and prevalence of STDs in HIV-infected individuals in the United States are difficult to estimate. Incidence varies both by local prevalence of the STD and by the HIV-infected population under consideration. For example, the incidence and prevalence of STDs may vary considerably when comparing men who have sex with men (MSM), women, or heterosexual men. In addition, most studies of STD incidence in HIV-infected patients have been limited to a relatively small number of clinics providing HIV and/or STD-related care, and there have been no published studies of longitudinal STD screening in asymptomatic HIV-infected men. Not surprisingly, individuals are often diagnosed with an STD at the same time they receive an initial diagnosis of HIV. One retrospective cohort study of men and women who sought care at an STD clinic in Baltimore revealed particularly high rates of STDs in both women and men at the time of HIV diagnosis (Figure 1); approximately one-third of them were symptomatic[7]. Nonetheless, even after receiving a diagnosis of HIV, the incidence of STDs in the cohort remained high at follow-up (7.0 STD cases/100 person years in men and 5.6 STD cases /100 person years in women) (Figure 2)[7]. In a separate study that involved HIV-infected women living in 14 cities in the United States, a baseline examination found evidence of an STD in 13% of the women, with more than 80% of these STD cases consisting of a diagnosis of trichomoniasis (Figure 3)[8]. Subsequent periodic STD screening of these women during a mean of 2.1 years revealed that 19% had infection or re-infection with Trichomonas vaginalis, and 2-3% acquired chlamydia, gonorrhea, or syphilis (Figure 4). Risk factors for STD acquisition were African-American ethnicity, sex with an injection-drug user, report of a previous STD, and detection of an STD at baseline. Other studies have also shown HIV-infected women to have a particularly high risk for trichomoniasis[9].

The resurgence of gonorrhea and syphilis among HIV-infected MSM in the United States (Figure 5 and Figure 6) clearly illustrates continued risk behavior in this group[10,11]. Depending on sexual practices, HIV-infected patients may also be at risk for STDs at non-genital sites. A recent cross-sectional study that predominantly involved male HIV-infected patients in San Francisco (most of whom were MSM) found that asymptomatic pharyngeal and rectal infections were significantly more common than asymptomatic urethral infections (Figure 7)[12]. Taken together, these data from multiple studies highlight the ongoing risk behavior that places HIV-infected persons at increased risk for acquiring and transmitting STDs and HIV.

Screening Guidelines

Because of the high prevalence of asymptomatic STDs in HIV-infected persons and the potential impact of STDs on both these individuals and their partners, the CDC, HRSA, and HIVMA issued guidelines in 2003 recommending routine periodic STD screening of asymptomatic HIV-infected individuals[5]. These guidelines advise that medical providers should make STD screening a high priority during the initial clinic visit with an HIV-infected patient. At this initial visit, all HIV-infected women should undergo screening for syphilis and trichomoniasis (Figure 8 STD Screening Recommendations for HIV-Infected IndividualsSTD Screening Recommendations for HIV-Infected Individuals). Screening for genital gonorrhea and chlamydia should also be considered in most sexually active HIV-infected women, and performed routinely in all HIV-infected women aged 25 years or younger (regardless of whether condom use was reported). Screening in women older than 25 years should be based on risk assessment, and would be indicated in a patient such as the one in the case presented here, who reports no condom use and has a partner who has other partners. Furthermore, HIV-infected women who report receptive oral or anal sex should undergo testing for pharyngeal gonorrhea (for oral sex) and rectal gonorrhea, and rectal chlamydia (for anal sex). Similarly, all HIV-infected men should be screened for syphilis at the initial visit. These STD screening guidelines also recommend consideration of testing for urethral chlamydia and gonorrhea at the initial visit. Among HIV-infected men who report receptive oral or anal sex (regardless of whether condom use was reported), testing for pharyngeal gonorrhea (for oral sex) and rectal gonorrhea and chlamydia (for anal sex) should be performed. Some experts also recommend routine serologic testing for herpes simplex virus type-2 (HSV-2), which causes most genital herpes in HIV-infected individuals[5]. Subsequent to the initial STD screening, further screening should be performed at least annually for all sexually active patients and as frequently as every 3 to 6 months for patients at higher risk for STDs (Figure 9). Finally, any patient who reports any symptoms consistent with an STD should receive immediate and appropriate clinical testing.

Preferred Tests for Screening

The 2003 CDC, HRSA, and HIVMA 2003 recommendations regarding STD screening in HIV-infected individuals provides a listing of preferred and alternative STD tests based on the suspected STD, the anatomic site of exposure, and the gender of the individual undergoing testing (Figure 10). Although a detailed account of the specific aspects of all tests available for STD screening is beyond the scope of this discussion, a few key points should be highlighted. First, screening for asymptomatic syphilis requires serologic testing, typically with a non-treponemal test (rapid plasma reagin [RPR] or Venereal Disease Research Laboratory [VDRL]) test; a positive RPR or VDRL test should then be quantified as a titer. If the patient has a positive non-treponemal test, it should be followed by a confirmatory treponemal antigen test (fluorescent treponemal antibody absorbed [FTA-ABS] or Treponema pallidum particle agglutination [TP-PA]). Second, several modalities are available to test for trichomoniasis, including microscopic examination of wet mount, culture of vaginal fluid, and rapid (point-of-care) antigen detection testing[13]. Third, nucleic acid amplification testing (NAAT) of first-catch urine (the initial 10-30 ml when starting to void) has greatly simplified testing for urogenital gonorrhea and chlamydia, and is generally considered as sensitive as NAAT of cervical or urethral swab specimens[14]. Although NAAT is not yet FDA-approved for pharyngeal or rectal specimens, some local laboratories have validated this approach (local STD programs can offer guidance in this rapidly evolving area). Otherwise, most providers use culture for rectal and pharyngeal gonorrhea screening; rectal chlamydia screening requires culture (if available) or direct fluorescent antibody testing. Chlamydial infection of the pharynx is rare and unlikely to be persistent or to cause symptoms; for this reason, pharyngeal screening is generally not recommended. Finally, for serologic screening for HSV-2, providers should use assays that detect glycoprotein G-based antibody (commonly termed "type-specific antibody"). Non-glycoprotein G-based antibody tests, while commonly used[15], have poor performance characteristics and are not recommended.

Case Summary

Saline microscopy of this patient's vaginal fluid performed in the clinic revealed motile trichomonads consistent with vaginal trichomoniasis. The provider obtained a pharyngeal swab for N. gonorrhoeae culture, a rectal swab for N. gonorrhoeae, C. trachomatis cultures, and a first-catch urine for NAAT for N. gonorrhoeae and C. trachomatis. Blood was drawn and sent to the lab for an RPR. A pregnancy test was also performed, and was negative. The patient's cultures were negative, but her RPR was positive at a titer of 1:16 (confirmed by FTA). She was treated appropriately for trichomoniasis and syphilis, and her partner was also tested and treated for syphilis and trichomoniasis. After she received the results of the positive STD tests, the patient stated that she was more motivated to use condoms, but was unsure if she would be able to use them 100% of the time. After a discussion of additional birth control options, she was prescribed oral contraceptive pills. Follow-up STD screening was planned within the next 3 to 6 months.