Sensitivity of treponemal tests for detecting prior treated syphilis during human immunodeficiency virus infection

CDC Laboratory Recommendations for Syphilis Testing, United States, 2024

This report provides new CDC recommendations for tests that can support a diagnosis of syphilis, including serologic testing and methods for the identification of the causative agent Treponema pallidum. These comprehensive recommendations are the first published by CDC on laboratory testing for syphilis, which has traditionally been based on serologic algorithms to detect a humoral immune response to T. pallidum. These tests can be divided into nontreponemal and treponemal tests depending on whether they detect antibodies that are broadly reactive to lipoidal antigens shared by both host and T. pallidum or antibodies specific to T. pallidum, respectively. Both types of tests must be used in conjunction to help distinguish between an untreated infection or a past infection that has been successfully treated. Newer serologic tests allow for laboratory automation but must be used in an algorithm, which also can involve older manual serologic tests. Direct detection of T. pallidum continues to evolve from microscopic examination of material from lesions for visualization of T. pallidum to molecular detection of the organism. Limited point-of-care tests for syphilis are available in the United States; increased availability of point-of-care tests that are sensitive and specific could facilitate expansion of screening programs and reduce the time from test result to treatment. These recommendations are intended for use by clinical laboratory directors, laboratory staff, clinicians, and disease control personnel who must choose among the multiple available testing methods, establish standard operating procedures for collecting and processing specimens, interpret test results for laboratory reporting, and counsel and treat patients. Future revisions to these recommendations will be based on new research or technologic advancements for syphilis clinical laboratory science.

Discordant Syphilis Immunoassays in Pregnancy: Perinatal Outcomes and Implications for Clinical Management

BACKGROUND

The reverse sequence algorithm is often used for prenatal syphilis screening by high-volume laboratories, beginning with a treponemal test such as the chemiluminescence immunoassay (CIA), followed by testing of CIA-positive (CIA(+)) specimens with the rapid plasma reagin test (RPR). The clinical significance of discordant serology (CIA(+)/RPR(-)) for maternal and neonatal outcomes is unknown.

METHODS

From August 2007 to August 2010, all pregnant women at Kaiser Permanente Northern California with discordant treponemal serology underwent reflexive testing with Treponema pallidum particle agglutination assay (TP-PA) and were categorized as "TP-PA confirmed" (CIA(+)/RPR(-)/TP-PA(+)) or "isolated CIA positive" (CIA(+)/RPR(-)/TP-PA(-)). Demographic variables and clinical data were abstracted from the medical record and compared by TP-PA status.

RESULTS

Of 194 pregnant women, 156 (80%) were CIA(+)/RPR(-)/TP-PA(-) and 38 (20%) were CIA(+)/RPR(-)/TP-PA(+). Among the 77 (49%) CIA(+)/RPR(-)/TP-PA(-) women who were retested, 53% became CIA(-). CIA(+)/RPR(-)/TP-PA(+) (n = 38) women were more likely to be older, have a prior history of sexually transmitted infections, and receive treatment for syphilis during pregnancy than women who were CIA(+)/RPR(-)/TP-PA(-) (all P < .005). Most pregnancies (189/194 [97.5%]) resulted in a live birth; there was no difference in birth outcomes according to TP-PA status and no stillbirths attributable to syphilis.

CONCLUSIONS

Most pregnant women with discordant serology were CIA(+)/RPR(-)/TP-PA(-); more than half who were retested became CIA(-). CIA(+)/RPR(-)/TP-PA(-) serology in pregnancy is likely to be falsely positive. Reflexive testing of discordant specimens with TP-PA is important to stratify risk given the likelihood of false-positive results in this population.

Syphilis in the AIDS era: diagnostic dilemma and therapeutic challenge

This review argues that syphilis has been underdiagnosed and undertreated, a problem that goes back to the beginning of the Wassermann era, and indeed long before. Non-treponemal tests do not detect the larger pool of persons with latent syphilis, the immunological consequences of which have not been systematically investigated in the context of HIV infection and progression to AIDS. Recent efforts to confirm the prevalence of syphilis in high-risk patients by reverse sequence screening, i.e. using a treponemal test first, as the screening test, have revealed untreated syphilis at higher rates than expected. Further testing using PCR discovered even more previously undetected cases. We suggest that latent syphilis is a chronic active immunological condition that drives the AIDS process and cannot be managed with the older Wassermann-based algorithm, and that non-treponemal tests have failed to associate syphilis with immune suppression since this screening concept was developed in 1906. In light of the overwhelming association between a past history of syphilis and HIV seroconversion, more sensitive tools, including recombinant antigen-based immunological tests and direct detection (PCR) technology, are needed to adequately assess the role of latent syphilis in persons with HIV/AIDS. Repeating older syphilis reinoculation studies may help establish a successful animal model for AIDS, and resolve many paradoxes in HIV science.

Infectious optic neuropathy

A wide variety of infectious agents are known to cause optic neuropathy. This article will consider the bacteria, spirochetes, fungi, and viruses that most commonly affect the optic nerve. Clinical presentation is variable, but some pathogens often produce a characteristic funduscopic pattern. Diagnosis is usually made on the basis of clinical suspicion and serologic testing. Polymerase chain reaction is also increasingly utilized. Most infectious agents can be effectively treated but visual recovery is highly variable.

[Bacterial, mycobacterial and fungal opportunistic infections in HIV-infected immigrants: diagnosis and treatment]

The number of HIV infected immigrants has increased sharply in Spain. These patients are prone to contracting several different types of opportunistic infections, including bacterial, mycobacterial, fungal and parasitic infections. The present article provides an in-depth review of bacterial and fungal infections, with particular emphasis on those not endemic in our country.

Serological diagnosis of syphilis: comparison of the Trep-Chek IgG enzyme immunoassay with other screening and confirmatory tests

The Trep-Chek IgG Enzyme Immunoassay (Trep-Chek IgG EIA) was evaluated with 604 serum specimens submitted for syphilis serology from patients across Canada against a battery of conventional syphilis serology tests, including the Rapid Plasma Reagin (RPR) test, the Venereal Disease Research Laboratory (VDRL) test, the Treponema pallidum passive particle agglutination (TP-PA) test, the fluorescent treponemal antibody absorption (FTA-ABS) test, and the newer confirmatory test, Innogenetics INNO-LIA. On the basis of a consensus result derived from these serologic tests, 34 specimens were found to be syphilis-positive (28 active and six past infections), and 570 were syphilis-negative (including 12 biological false positives). When the test results on this set of samples were compared to those obtained with the conventional tests RPR, VDRL, TP-PA, and FTA-ABS, the sensitivity and specificity of the Trep-Chek IgG EIA were found to be 85.3% and 95.6%, respectively. Without further evaluation, we do not recommend use of the Trep-Chek IgG EIA as a stand-alone test for either screening or confirmatory syphilis serology.

Syphilis in the United States: an update for clinicians with an emphasis on HIV coinfection

Diagnosis and treatment of syphilis are challenging because of its variable clinical presentation and course and the lack of definitive tests of cure after treatment. This review of the most recent literature on the epidemiology, clinical manifestations, current diagnosis, and treatment of syphilis is focused toward clinicians who treat patients with this disease. Syphilis coinfection with human immunodeficiency virus is emphasized because it is increasingly common in the United States and affects the initial presentation, disease course, diagnosis, and treatment of syphilis. Of particular consequence is the effect of human immunodeficiency virus on the clinical diagnosis, prevalence, and course of neurosyphilis, one of the most serious consequences of syphilis infection.

Syphilis Treatment and HIV Infection in a Population-Based Study of Persons at High Risk for Sexually Transmitted Disease/HIV Infection in Lima, Peru

OBJECTIVES

The objective of this study was to characterize syphilis epidemiology and the relationship of HIV status and initial rapid plasma reagin (RPR) titer to syphilis treatment in Lima, Peru.

STUDY DESIGN

We screened 1,261 individuals at high risk for sexually transmitted diseases for syphilis and HIV infection. Syphilis was treated with penicillin injection or doxycycline; treatment was repeated in unresponsive cases.

RESULTS

: The prevalence of syphilis was 7.7%, 1-year incidence rate was 4.7%, and reinfection rate was 42.7%. The treatment success rate was 93.4% (71 of 76); those with initial RPR titers <or=1:8 were less often treated successfully (86.8% vs. 100%, P = 0.054) and required additional treatment more often (26.2% vs. 7.7%, P = 0.028) than those >or=1:16. HIV infection was associated with syphilis, prevalent in 15.6% and 3.7% of those with and without syphilis, respectively (P < 0.001), but did not affect treatment success (90.9% vs. 93.8%).

CONCLUSIONS

Syphilis was common, associated with HIV infection, and less responsive to therapy in those with initial RPR titers <or=1:8. HIV infection did not affect syphilis treatment success rates.

Syphilitic uveitis in patients infected with human immunodeficiency virus

BACKGROUND

This work investigates the incidence and clinical features of syphilitic uveitis in patients infected with human immunodeficiency virus (HIV).

MATERIAL AND METHODS

We retrospectively reviewed syphilitic uveitis in patients coinfected with HIV that presented at a referral center between July 2001 and November 2003.

RESULTS

Twelve patients (20 eyes) were included. The ocular manifestations of syphilis led to the discovery of HIV-1 seropositivity in three patients. All patients were male and homosexual. One patient has been previously treated for syphilis with benzathine penicillin G. One patient presented with anterior uveitis and 11 patients had panuveitis or posterior uveitis. Necrotizing retinitis was noted in seven eyes (35%), posterior placoid chorioretinitis in six eyes (30%) and optic nerve involvement in five eyes (25%). Of nine patients with available cerebrospinal fluid (CSF) studies, seven (77.8%) had CSF abnormalities. Eleven patients were treated with intravenous penicillin G and one with intravenous ceftriaxone sodium. One patient required a second course of antibiotics to control uveitis. Ocular inflammation decreased and visual acuity improved in all nine patients for whom follow-up was available after treatment.

CONCLUSION

Manifestations of syphilitic uveitis in HIV-infected patients are multiple, with high frequencies of posterior uveitis, posterior placoid chorioretinitis, necrotizing retinitis and optic nerve involvement. Syphilitic uveitis in HIV-infected patients seems to have a more severe course and may relapse despite high-dose intravenous penicillin therapy.

Medical history, sexual, and maturational factors and prostate cancer risk

PURPOSE

Sexual, physical, and medical factors were investigated in a case-control study of prostate cancer.

METHODS

This population-based study, conducted from 1995 to 1999 in northeastern Ontario, used cancer registry-identified cases (n=760), aged 45 to 84 years, diagnosed between 1995 and 1998. Age-frequency matched controls (n=1632) were obtained from telephone listings. Two separate logistic regression analyses considered: 1) sexual and physical; and 2) medical factors.

RESULTS

For the sexual-physical model, marital status, family income, maximum height, number of marriages, having children, age at first marriage, birth, and needing to shave, and acne were not significantly related to risk. In the medical model, a family history of prostate cancer (OR, 2.99; 95% CI, 2.21-4.04) and history of venereal disease (OR, 2.12; 95% CI, 1.27-3.53) were associated with significantly increased risk. A history of allergies (OR, 0.78; 95% CI, 0.60-1.00), benign prostatic hyperplasia (OR, 0.63; 95% CI, 0.49-0.81), and an annual physical exam (OR, 0.43; 95% CI, 0.21-0.85) were associated with reduced risk. Other factors considered in the medical conditions model, body mass index, smoking non-filter cigarettes, and family income were not associated with prostate cancer.

CONCLUSIONS

This study is consistent with other studies that suggest that infectious agents may be involved in prostate cancer development.

Posterior segment manifestations of HIV/AIDS

The ocular posterior segment manifestations of AIDS may be divided into four categories: retinal vasculopathy, unusual malignancies, neuro-ophthalmologic abnormalities, and opportunistic infections. Microvasculopathy is the most common manifestation. Opportunistic infections, particularly cytomegalovirus retinitis and progressive outer retinal necrosis, are the most likely to result in visual loss due to infection or subsequent retinal detachment. Diagnosis and treatment are guided by the particular conditions and immune status of the patient.

Visceral leishmaniasis in immunocompromised patients with and without AIDS: a comparison of clinical features and prognosis

Visceral leishmaniasis is basically a disease of healthy infants and adults. However, in the last decade an increasing number of cases of kala azar in immunocompromised patients have been reported with emphasis on atypical manifestations of the disease. During a period of 11 years, 20 immunocompromised patients with AIDS (12 patient), haematological neoplasia (3 patients), corticosteroid therapy (3 patients) or renal transplantation (2 patients) were studied by one or more of the authors. We did not find differences in the presentation of leishmaniasis between patient with or without AIDS and most patients had fever, enlargement of the liver and spleen, blood cytopenias and biochemical abnormalities. Serology was more frequently positive in HIV-negative than in HIV-positive patients (100% versus 63.6%; P=0.13). Bone marrow biopsy was diagnostic in 66% and 87% of patients with and without AIDS, respectively. Failure of anti-leishmanial therapy occurred in 6 of 19 patients treated (31.5%), and 3 patients with AIDS and another 3 without AIDS died during the first episode of leishmaniasis. Of 12 survivors, relapses occurred in five (41.6%). Only patients in whom immunosuppression was ameliorated by means of antiretroviral therapy or by reduction of corticosteroid and other immunosuppressive drugs did not relapse. Treatment of kala azar in immunocompromised host is in satisfactory and new drugs or strategies are urgently needed.

Ocular syphilis

Although the annual incidence of primary and secondary syphilis has dropped to the lowest rate recorded, syphilis remains an important cause of ocular disease. Uveitis is the most common ocular manifestation of syphilis in both HIV-positive and HIV-negative patients, and the diagnosis should prompt an analysis of the cerebrospinal fluid to exclude associated neurosyphilis. Newer modalities such as enzyme immunoassays and genomic amplification using the polymerase chain reaction may prove to be useful techniques to detect Treponema pallidum in intraocular specimens. The preferred treatment for all stages of syphilis remains parenteral penicillin G, although the preparation, dose, route of administration, and duration of therapy are dictated by the stage of disease and various host factors. All patients diagnosed with ocular syphilis should be tested for HIV, because the presence of a primary genital chancre increases the risk of acquiring or transmitting HIV, and because risk factors for the two diseases are similar.

Posterior segment manifestations of active ocular syphilis, their response to a neurosyphilis regimen of penicillin therapy, and the influence of human immunodeficiency virus status on response

OBJECTIVE

To determine the relative frequencies of signs in posterior segment ocular syphilis, the response to a neurosyphilis regimen of penicillin, and differences in findings between human immunodeficiency virus (HIV)-coinfected and -noncoinfected patients in a community setting.

DESIGN

Retrospective, noncomparative, consecutive case series.

PARTICIPANTS

Fourteen consecutive patients with posterior segment ocular syphilis over a 14-year period within or during the acquired immune deficiency syndrome era.

INTERVENTION

Neurosyphilis intravenous penicillin regimen.

MAIN OUTCOME MEASURES

Initial and final visual acuity; treponemal and nontreponemal serologic analyses; cerebrospinal fluid cell count, protein, and Venereal Disease Research Laboratory analyses; posterior segment signs; and relapses and recurrences.

RESULTS

Blacks and males were predominantly affected. Five (36%) of patients were HIV coinfected, and ocular syphilis led to the HIV infection diagnosis in three. Four (29%) patients had received previous antibiotic therapy for primary or secondary syphilis, raising the suspicion of relapse. Two patients had negative nontreponemal serologic results. All patients responded rapidly to neurosyphilis therapy. One patient subsequently relapsed after neurosyphilis therapy, and a second was reinfected with recurrence of ocular involvement. One previously undescribed retinal manifestation was discovered: a sectorial retinochoroiditis with delayed retinal circulation in the involved area.

CONCLUSIONS

Ocular syphilis is a form of neurosyphilis and requires neurosyphilis therapy regardless of when it develops after primary infection. Conventional syphilis staging is of little use in understanding ocular syphilis. A high suspicion for this diagnosis is appropriate, especially in poorer black males with posterior segment inflammatory disease. Human immunodeficiency virus coinfection with ocular syphilis is common, but does not affect response to a neurosyphilis regimen of penicillin in the short term. Awareness of the multiple presentations of posterior segment ocular syphilis will aid ophthalmologists in averting misdiagnosis or delayed diagnosis.

Central Nervous System Opportunistic Infections in HIV-1 Infection

Neurologic disease is commonly encountered in the population infected with human immunodeficiency virus type 1 (HIV-1). Although HIV-1 is responsible for many of these neurologic complications, other organisms will affect the nervous system as the immune deficiency state progresses. With the wide use of potent antiretroviral therapy, the mortality from and incidence of opportunistic infections (OIs) among persons with advanced HIV-1 infection has decreased. Nevertheless, these diseases are still seen frequently, especially among those with limited access to new antiretroviral therapies. Therefore, it remains important to recognize the most common OIs of the central nervous system (CNS) as well as primary CNS lymphoma, which will be the focus of this review.

Syphilis testing

The organism that causes syphilis, Treponema pallidum, is impossible to culture in the clinical laboratory. Direct visualization of the pathogen is one laboratory technique used in the diagnosis of syphilis. Currently, serologic testing is the most widely used laboratory technique in diagnosing syphilis and monitoring its course after treatment. Serologic tests are divided into two categories, the nontreponemal and treponemal antibody tests. Newer techniques such as enzyme immunoassays have shown excellent results.

The immune compromised host in the twenty-first century: management of mucocutaneous infections

Infectious diseases encountered in dermatology have changed tremendously during the past few decades with the emergence of the immunocompromised host. This change is a result of the human immunodeficiency virus epidemic, use of immunomodulating drugs, bone marrow transplantation, increasing prevalence of diabetes mellitus, and an aging population. New pathogens have been discovered and new disorders have occurred. In the compromised host, infection can be more aggressive and widespread locally, be caused by opportunistic pathogens, and be disseminated hematogenously from or to the skin. The prevalence of nonmelanoma skin cancer has increased, and squamous cell carcinomas can be more aggressive with more rapid local growth as well as frequency of metastasis.

Sexual behaviour, STDs and risks for prostate cancer

A population-based case-control study was carried out among 981 men (479 black, 502 white) with pathologically confirmed prostate cancer and 1315 controls (594 black, 721 white). In-person interviews elicited information on sexual behaviour and other potential risk factors for prostate cancer. Blood was drawn for serologic studies in a subset of the cases (n = 276) and controls (n = 295). Prostate cancer risk was increased among men who reported a history of gonorrhoea or syphilis (odds ratio (OR) = 1.6; 95% confidence internal (CI) 1.2-2.1) or showed serological evidence of syphilis (MHA-TP) (OR = 1.8; 95% CI 1.0-3.5). Patterns of risk for gonorrhoea and syphilis were similar for blacks (OR = 1.7; 95% CI 1.2-2.2) and whites (OR = 1.6; 95% CI 0.8-3.2). Risks increased with increasing occurrences of gonorrhoea, rising to OR = 3.3 (95% CI 1.4-7.8) among subjects with three or more events (Ptrend = 0.0005). Frequent sexual encounters with prostitutes and failure to use condoms were also associated with increased risk. Syphilis, gonorrhoea, sex with prostitutes and unprotected sexual intercourse may be indicators of contact with a sexually transmissible factor that increases the risk of prostate cancer.

Human immunodeficiency virus infection and genital ulcer disease in South Africa: the herpetic connection

BACKGROUND AND OBJECTIVES

While genital ulcers are a risk factor in HIV infection, the association of specific agents of genital ulcer disease (GUD) with HIV infection may vary.

GOAL

To determine the etiology of GUD in HIV-infected and HIV-uninfected men attending sexually transmitted disease (STD) clinics in Durban, Johannesburg, and Cape Town, South Africa, and the association of previous and current sexually transmitted infections with HIV infection in men with ulcerative and nonulcerative STDs.

STUDY DESIGN

A cross-sectional study of 558 men with genital ulcers and 602 men with urethritis.

RESULTS

Patients with GUD were more likely to be infected with HIV than patients with urethritis (39.4% versus 21.4%, P< or =0.001). Herpes simplex virus 2 (HSV-2) was the most common agent identified in ulcer specimens (35.9%), and was detected in a significantly higher proportion of ulcer specimens from HIV-infected patients than in specimens from HIV-uninfected patients (47.4% versus 28.2%, P< or =0.001). Patients infected with HIV-1 were significantly more likely to have HSV-2 infection, as measured by the presence of the antibody to glycoprotein G-2, than patients not infected with HIV (63.1% versus 38.5%, P< or =0.001). Patients infected with HIV-1 were also significantly more likely to have initial HSV-2 infection than HIV-uninfected patients with GUD (50.0% versus 31.6%, P = 0.007). Haemophilus ducreyi was detected in 31.7% of ulcer specimens; prevalence did not vary by HIV-infection status. Treponema pallidum DNA was detected significantly less frequently in ulcer specimens from patients infected with HIV than in specimens from patients not infected with HIV (10.2% versus 26%, P< or =0.001); no association was found between HIV-infection status and fluorescent treponemal antibody absorption test seroreactivity, even when men with M-PCR-positive syphilis lesions were excluded from the analyses.

CONCLUSION

The authors found that HSV-2 is a more common etiology of GUD than has been suggested by previous studies conducted in South Africa; serologic evidence of HSV-2 infection and current cases of genital herpes are strongly associated with HIV infection among men who present to STD clinics with GUD or urethritis.

Laboratory methods of diagnosis of syphilis for the beginning of the third millennium

Despite that the whole genome of T. pallidum, the causative agent of syphilis, has been sequenced, syphilis is, and will remain for some time, diagnosed by direct clinical observation and by laboratory methods. This review presents comprehensively most of the practical techniques used for direct detection of T. pallidum and lists all practical methods for phospholipid and treponemal antibodies detection. It describes most novel tests for syphilis, discusses problems with sero-creossreactivity in Lyme disease, immune responses in HIV-syphilis coinfected patients, and reviews serologic responses to antibiotic treatment.

Syphilis: review with emphasis on clinical, epidemiologic, and some biologic features

Syphilis is a chronic disease with a waxing and waning course, the manifestations of which have been described for centuries. It occurs worldwide, and the incidence varies significantly with geographic location. Transmission is mainly by sexual contact. The causative organism, Treponema pallidum, was first described in 1905, but because of the inability to culture the organism and the limitations of direct microscopy, serologic testing is the mainstay of laboratory diagnosis. The disease has been arbitrarily divided into several stages. The primary stage is defined by a chancre at the site of inoculation. The secondary stage is characterized by a polymorphic rash, lymphadenopathy, and other systemic manifestations. A variable asymptomatic latent period follows, which for epidemiologic purposes is divided into early (<1 year) and late (>1 year) stages. The early stages (primary, secondary, and early latent) are potentially infectious. The tertiary stage is the most destructive and is marked by cardiovascular and neurologic sequelae and gummatous involvement of any organ system. Congenital infection may result in protean early or late manifestations. Unlike many other bacteria causing infectious diseases, the organism remains sensitive to penicillin, and this remains the mainstay of therapy.

TORCH testing in HIV-infected women

The issue of TORCH testing in pregnant women infected with the HIV virus remains confusing, even more so than it is in the non-HIV-infected gravida. Unfortunately, the data presented in this article make the recommendations of how to test for these various infections in pregnancy that much more difficult. Patients who are newly diagnosed as being HIV-infected and referred for prenatal care or who have not had TORCH testing probably should be tested. Thus, the prenatal patient with newly diagnosed HIV infection should be tested for T. gondii IgG antibodies. If positive for IgG antibodies, IgM antibodies should be obtained in an attempt to rule out acute T. gondii infection. Patients who test negative do not require any further testing until after the pregnancy unless they are severely immunocompromised and show signs and symptoms of toxoplasmosis. Antibodies (IgG) to CMV should be obtained in the HIV-infected gravida who is at high risk for CMV disease, i.e., patients with CD4+ T cell counts less than 100/mm3. Unfortunately, the previously described problems with antibody detection make this testing less than ideal; thus, it is not routinely recommended in the HIV-infected pregnant patient who presents for prenatal care except for those at risk of disease reactivation. As for herpes simplex virus testing, there is no value in routinely testing patients prenatally for evidence of the disease. Finally, syphilis testing in the HIV-infected gravida is of major importance. Once tested, the patient who tests negative and who remains at risk for infection should probably be retested in the third trimester. Patients who are found to have the disease and who are treated need to be tested serially to rule out re-infection or treatment failure.

The association of false-positive rapid plasma reagin results and HIV infection

BACKGROUND AND OBJECTIVES

To study the relationship between a false positive rapid plasma reagin (RPR) result (FP), syphilis, and HIV infection in our patients.

METHODS

A prospective study of the incidence of FP tests and syphilis in the general population and its relationship to HIV infection over a period of 6 months.

RESULTS

8.76% of the population were HIV positive. False positives were found in 15% and 1.2% of the HIV infected and noninfected patients, respectively; the attributable risk for HIV was 14.97. Syphilis was found in 5% and 0.9% of the positive and negative HIV patients, respectively; the attributable risk for HIV was 5.4.

CONCLUSIONS

The incidence of false positive RPR results in the HIV-infected population is significantly higher than that of the non-HIV-infected patients.

Treponemal specific tests for the serodiagnosis of syphilis. Syphilis and HIV Study Group

OBJECTIVES

To determine the rate of concordance of the Microhemagglutination Assay for Antibodies to T. pallidum (MHA-TP) and the Fluorescent Treponemal Antibody-Absorption test (FTA-ABS) prior to therapy in patients with early stage syphilis and to assess the incidence of and associated risk factors for seroreversion of these treponemal specific tests during the first year after therapy for early syphilis.

DESIGN

Multicenter, prospective, cohort treatment study of patients with early syphilis.

METHODS

Five hundred twenty-five patients were enrolled in a study to evaluate the response of early syphilis to either benzathine penicillin 2.4 million units intramuscularly once or this therapy plus amoxicillin 2 g and probenecid 500 mg orally both three times daily for 10 days. Serologic and clinical follow-up was conducted at intervals over 1 year. MHA-TP and FTA-ABS tests were performed on serologic specimens from each patient visit.

RESULTS

Enrollment specimens showed 5% discordant MHA-TP and FTA-ABS results with 85% of these demonstrating a nonreactive MHA-TP. This occurred most commonly in primary syphilis. In patients who had a 1-year serologic follow-up with FTA-ABS or MHA-TP, seroreversion occurred in 9% and 5% of cases, respectively. No association between HIV-seropositivity and TST seroreversion was demonstrated.

CONCLUSION

The MHA-TP may be less sensitive than the FTA-ABS for identifying patients with primary syphilis. Treponemal specific tests may become nonreactive during the first year after therapy for early syphilis.

Novel recombinant-antigen enzyme immunoassay for serological diagnosis of syphilis

Enzyme immunoassay (EIA) is an ideal method for screening large numbers of patients for syphilis. We evaluated a novel immune-capture EIA (ICE Syphilis; Murex Diagnostics) that uses three recombinant Treponema pallidum antigens (TpN15, TpN17, and TpN47) and compared the results with those obtained by the native T. pallidum antigen EIA (Captia SelectSyph-G; Centocor) that we currently use for the serodiagnosis of syphilis. Specificity was evaluated by screening 1,184 unselected serum specimens in parallel by the ICE Syphilis and SelectSyph-G assays, while sensitivity was tested with a panel of 101 serum specimens containing antitreponemal antibodies (treated and untreated) from patients with various stages of infection. The specificity of the ICE Syphilis EIA (99.8%) on screening was significantly higher (P < 0.02) than that of the SelectSyph-G EIA (99.2%). The sensitivity of the ICE Syphilis EIA was significantly higher (P < 0.01) than that of the SelectSyph-G EIA on both initial (99 versus 91.4%) and repeat (100 versus 92.4%) testing. The ICE Syphilis EIA was also significantly more sensitive (P < 0.01) than the fluorescent treponemal antibody-abs (92.4%) but not the T. pallidum hemagglutination assay (97.1%). Sera containing antitreponemal antibodies gave a much higher antibody index (absorbance of test serum/kit cutoff) by the ICE Syphilis EIA than by the SelectSyph-G EIA. This combined with the overall high sensitivity makes the ICE Syphilis EIA an ideal test for excluding or detecting treponemal infection in human immunodeficiency virus (HIV)-infected patients. The ICE Syphilis EIA was positive with sera from all 15 HIV-infected patients in the study, whereas sera from 3 HIV-infected patients were negative by the SelectSyph-G EIA. We conclude that the high sensitivity and specificity of the ICE Syphilis EIA and its suitability for automation make it an ideal screening test.

Definitions of genital ulcer disease and variation in risk for prevalent human immunodeficiency virus infection

OBJECTIVES

Although genital ulcer disease (GUD) has been associated with human immunodeficiency virus (HIV) infection in a number of studies, definitions of genital ulceration have varied. The authors hypothesized that the association of GUD with prevalent HIV infection may vary according to the definition of GUD that is used.

METHODS

As part of a prospective cohort study, 863 patients were interviewed and examined who presented to a sexually transmitted disease (STD) clinic for new symptom evaluation and who agreed to HIV testing to determine demographic and behavioral risk associated with prevalent HIV infection. To determine the association between GUD and prevalent HIV, the following definitions of GUD were used: observed ulcers, history of syphilis, serologic evidence of syphilis, observed culture-proven genital herpes, and serologic evidence of herpes simplex virus type II (HSV-2) infection.

RESULTS

Of 481 men and 382 women enrolled, prevalent HIV infection was detected in 12.5% and 5.2%, respectively. In multivariate analyses controlling for known HIV risk behaviors, prevalent HIV infection was associated with observed GUD (odds ratio [OR] = 2.0, 95% confidence intervals (CI) = 1.0-3.9), a history of syphilis (OR = 6.0, CI = 2.8-12.7), and serologic evidence of syphilis (OR = 3.7, CI = 1.9-7.0), but not with serologic evidence of HSV-2 (OR = 1.2, CI = 0.7-2.1), nor with observed HSV-2 culture-positive genital ulcerations (OR = 1.0, CI = 0.4-4.2). Factors contributing to different strengths of association between HIV infection and a history of syphilis or serologic evidence of syphilis included the presence of underdiagnosed syphilis infection in people with reactive serologic tests and the absence of serologic reactivity in people with a positive history.

CONCLUSIONS

Although GUD is strongly associated with prevalent HIV, the strength of the association depends on the definition of GUD used. For accurate evaluation of people at risk for HIV, clinicians and researchers should use multiple definitions of GUD.

Ophthalmic complications of HIV infection

HIV retinopathy, a noninfectious microangiopathy, is the most common ocular manifestation of HIV infection. Opportunistic infections, neoplasms, neuro-ophthalmic lesions, and drug-induced lesions may also cause ocular problems. Opportunistic ocular infections, particularly CMV retinitis, are a major cause of morbidity in patients with AIDS. Because of the underlying chronic and progressive immune dysfunction, the ocular symptoms, signs, clinical course, and treatment are often atypical and severe, requiring protracted medical therapy.

Neurosyphilis in HIV-infected patients

To determine the prevalence and the clinical and serological findings of neurosyphilis in HIV-infected patients, Treponema pallidum hemagglutination (TPHA) tests, CD4+ lymphocyte counts and determination of rapid plasma reagin (RPR) titers were performed in 972 HIV-infected patients over a period of 3.5 years. Patients were scored according to the Centers for Disease Control's classification for HIV infection. Reactive serum syphilis tests and positive cerebrospinal fluid (CSF)-Venereal Disease Research Laboratory (VDRL) tests, with or without clinical symptoms, were used as the criteria for diagnosis of neurosyphilis. The TPHA test was positive in 31 patients, representing 3.1% of all HIV-infected patients included in the study. Of these, 13 were intravenous drug addicts, 14 were homosexuals and 4 were heterosexuals. Diagnosis of syphilis was concurrent with HIV infection in 19 patients, prior to HIV infection in 6 patients and after HIV infection in 6 patients. CSF examinations were performed in 28 of the 31 (90.3%) patients with serologically evident syphilis. Four patients had positive CSF-VDRL tests with pleocytosis (23.5% of untreated syphilis patients in whom CSF was examined), three of whom reported mild headache, which was considered a doubtful manifestation of neurosyphilis. Patients with syphilis diagnosed and treated prior to diagnosis of HIV infection did not have evidence of neurosyphilis. Seven patients had pleocytosis with a negative CSF-VDRL test, without any clinical manifestations of neurosyphilis. There was no significant difference in the mean CD4+ lymphocyte count between patients with and without neurosyphilis (p = 0.5). RPR titers in neurosyphilis patients were greater than those in patients previously treated for syphilis and in those with pleocytosis only (p = 0.046 and 0.036, respectively). All neurosyphilis patients had an RPR titer > 1:8. After therapy, neurosyphilis patients had negative CSF-VDRL tests with a lower level of pleocytosis. The prevalence of neurosyphilis was 0.4% in HIV-infected patients and 23.5% in HIV-infected patients with untreated syphilis. This high prevalence of neurosyphilis warrants CSF examination in HIV-infected patients with syphilis, regardless of the stage of syphilis.

Markers of past syphilis in HIV infection comparing Captia Syphilis G anti-treponemal IgG enzyme immunoassay with other treponemal antigen tests

The sensitivity of the Captia Syphilis G anti-treponemal IgG enzyme immunoassay (EIA-IgG) was compared with the Treponema pallidum haemagglutination assay (TPHA) and the Fluorescent Treponemal Antibody Absorbed (FTA-Abs) test as a marker for past syphilis in 28 HIV-infected and 31 HIV-negative patients with a past history of syphilis. The specificity of EIA-IgG was compared in 89 patients without a history of syphilis who were known to be HIV antibody positive with a control group of 89 patients who had tested HIV negative. In patients with a past history of syphilis each treponemal test (EIA-IgG, TPHA and FTA-Abs) gave a lower sensitivity (82%, 86%, 79%) in the HIV-positive group than in the HIV-negative group (97%) but the difference was significant only in the case of the FTA-Abs test (P < 0.05). In the HIV-positive patients 11% (3/28) were negative in all 3 treponemal tests while 25% (7/28) were negative in at least one treponemal test. In patients without a past history of syphilis the EIA-IgG antibody index in the HIV-positive group (0.436) was significantly higher than in the HIV-negative group (0.378): the specificity, however, was similar in the HIV-positive (100%) and HIV-negative group (99%). We conclude that the Captia Syphilis G anti-treponemal IgG enzyme immunoassay is of similar specificity in HIV-positive and HIV-negative patients and is of similar sensitivity to the TPHA and FTA-Abs as a marker of past syphilis in HIV-infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory diagnosis and interpretation of tests for syphilis

The lack of a method for demonstrating the presence of Treponema pallidum by growth necessitates the use of alternative methods. Traditionally, these methods are divided into direct detection methods (animal inoculation, dark-field microscopy, etc.) and serologic tests for the presence of patient antibody against T. pallidum. Serologic methods are further divided into two classes. One class, the nontreponemal tests, detects antibodies to lipoidal antigens present in either the host or T. pallidum; examples are the Venereal Disease Research Laboratory and rapid plasma reagin and tests. Reactivity in these tests generally indicates host tissue damage that may not be specific for syphilis. Because these tests are easy and inexpensive to perform, they are commonly used for screening, and with proper clinical signs they are suggestive of syphilis. The other class of test, the treponemal tests, uses specific treponemal antigens. Confirmation of infection requires a reactive treponemal test. Examples of the treponemal tests are the microhemagglutination assay for antibodies to T. pallidum and the fluorescent treponemal antibody absorption test. These tests are more expensive and complicated to perform than the nontreponemal tests. On the horizon are a number of direct antigen, enzyme-linked immunosorbent assay, and PCR techniques. Several of these techniques have shown promise in clinical trials for the diagnosis of congenital syphilis and neurosyphilis that are presently difficult to diagnose.

A preliminary evaluation of a prototype western blot confirmatory test kit for syphilis

A prototype Western blot kit was evaluated as a confirmatory test for syphilis using 131 sera characterized by other serological tests for syphilis. There were 114 treponemal sera (including 94 cases of early syphilis, 83 of which were untreated) and 17 non-treponemal problem sera (11 gave false positive reactions on screening with the TmpA recombinant antigen enzyme immunoassay (EIA), 3 gave false positive fluorescent treponemal antibody absorbed (FTA-abs) tests, and 3 false positive Captia Syphilis G EIA results). Based on the manufacturer's criteria of reactivity in multiple bands for designating a positive result the Western blot test gave a sensitivity of 99.1% (113/114) and a specificity of 88.2% (15/17) when indeterminate reactions were scored positive and 98.2% (112/114) and 100% (17/17) when indeterminate reactions were scored negative. Sensitivity was high in both treated and untreated infection. Corresponding sensitivities for the TPHA and FTA-abs when equivocal reactions were scored negative were 97.5% (111/114) and 99.1% (113/114). The high sensitivity of the FTA-abs in this study is probably due to the large number of untreated primary infections. Our results with the Western blot, confirm earlier studies using 'in-house' test systems and, support a role for a commercial Western blot test in the confirmatory diagnosis of syphilis. Further studies are required to confirm the high specificity and sensitivity of the kit in a larger series including a wider variety of non-treponemal cases as well as patients with untreated and treated infection.

Cerebrospinal fluid proteins in neurosyphilis and HIV infection

This paper briefly reviews the factors which influence the concentrations of proteins, particularly immunoglobulins, within the CSF and how antibodies which are locally synthesized within the central nervous system can be detected by the laboratory. The use of nitrocellulose immunoblotting for the identification of antibodies which are specific to Treponema pallidum and Human Immunodeficiency Virus Type-1 are discussed.

Serial MRI of the brain in asymptomatic patients infected with HIV: results from the UCMSM/Medical Research Council neurology cohort

Seventy-six homosexual or bisexual men underwent two cranial MRI studies at a mean interval of 13 months; 23 were HIV seronegative, 41 seropositive but asymptomatic (Center for Disease Control (CDC) groups II/III), and 12 had AIDS related complex (ARC)/AIDS (CDC group IV). Agreement between two neuroradiologists was rated as very good for assessment of enlargement of ventricles and good for widening of cerebral sulci and the presence of focal lesions. For assessment of serial studies, the agreement was moderate. The prevalence of cerebral atrophy and focal white matter lesions was no higher in the asymptomatic patients (CDC group II/III) than in appropriate seronegative controls. Some patients with ARC/AIDS showed evidence of developing cerebral atrophy during the study period when serial scans were compared. The imaging evidence supports the other data obtained from this cohort, which suggest that no significant CNS involvement occurs in HIV infection before the development of ARC/AIDS.

A review and update on adult syphilis, with particular reference to its treatment

Syphilis has become less common in Europe in the last decade, but has once again become a major problem in the USA, and remains so in many developing countries. Several treponemal genes have now been cloned and expressed in Escherichia coli, allowing study of treponemal proteins. The importance of cell mediated immunity in syphilis has been demonstrated in animal models. A diagnosis of syphilis is usually confirmed by dark-field microscopy or serological tests. Seroconversion may be delayed in HIV infected individuals. A positive reaginic test in cerebrospinal fluid (CSF) has a high specificity but low sensitivity in the diagnosis of neurosyphilis. Indeed, virulent treponemes can be identified in CSF samples which have negative reaginic tests, normal cell counts and protein levels. In the CSF, the FTA-Abs test has a high sensitivity but low specificity for neurosyphilis. Penicillin remains the treatment of choice for all stages of syphilis, although it penetrates the blood brain barrier poorly. Treatment with intramuscular benzathine penicillin 2.4 million units stat, or 600,000 units procaine penicillin daily does not produce treponemicidal levels within the CSF. However, the incidence of neurosyphilis is low in immunocompetent patients treated with such regimens during early syphilis. Acceptable alternatives in penicillin-allergic patients include ceftriaxone and doxycycline. Erythromycin is not recommended as it has produced unacceptably high rates of treatment failure. Recently, a strain of macrolide-resistant Treponema pallidum was isolated from a patient with secondary syphilis. For the treatment of neurosyphilis, treponemicidal levels of penicillin can be achieved in the CSF using 2.4 million units procaine penicillin daily with concurrent probenecid 500 mg 4 times a day, or an intravenous infusion of benzyl penicillin 12-24 million units daily. Early syphilis can be treated adequately over 10 days, but 21 to 28 days is appropriate for late syphilis. In HIV-infected patients syphilis may present atypically with initially negative serological tests. Treatment of early syphilis in HIV-positive patients has been associated with the early development of neurosyphilis. It is advisable to treat all patients co-infected with HIV with an antibiotic regimen that achieves adequate levels within the CSF.

Determining the prevalence of neurosyphilis in a cohort co-infected with HIV

A retrospective study of 767 HIV positive patients from a large urban public hospital, 238 of whom were co-infected with syphilis, was performed to determine the prevalence of neurosyphilis. A prevalence of 3% of neurosyphilis in the co-infected cohort was demonstrated. The 7 cases of neurosyphilis ascertained were of the early stage variety, with cranial nerve involvement the predominant focal deficit. Of the 5 cases presenting after initial diagnosis and treatment of syphilis, 4 were felt to be inadequately treated. An overall prevalence of 1% (7/767) was determined for the entire HIV(+) cohort. The majority of the cases of syphilis (90%) were characterized as latent syphilis. Based on these findings, the authors recommend routine CSF examination in all patients who are HIV positive and who present with latent syphilis. Treatment regimens should be maximized in an effort to reduce the prevalence of neurosyphilis in such a co-infected cohort.