Performance of a commercial, type-specific enzyme-linked immunosorbent assay for detection of herpes simplex virus type 2-specific antibodies in Ugandans

Two hundred forty-eight human immunodeficiency virus (HIV)-positive and 496 HIV-negative subjects in Uganda were tested by HerpeSelect herpes simplex virus type 2 enzyme-linked immunosorbent assay (ELISA) and Western blotting to optimize the ELISA for use in this population. A higher index cutoff value was required for optimal sensitivity and specificity, and overall performance of the assay was not affected by HIV status.

Comparison of three nucleic acid amplification tests for detection of Chlamydia trachomatis in urine specimens

Traditionally, culture and immunoassays have been performed for the detection of sexually transmitted diseases, including Chlamydia trachomatis. However, these assays may often require invasive specimen collection methods, such as female cervical and male urethral swabs. Recently, nucleic acid amplification tests (NAATs) have been approved for testing for the presence of C. trachomatis in urine samples. Our objective was to compare the sensitivities and specificities of C. trachomatis detection in urine samples with three NAATs: the Abbott LCx (LCx), BD ProbeTec ET (ProbeTec), and Gen-Probe APTIMA Combo 2 (AC2). Urine specimens (n = 506) were collected from both symptomatic and asymptomatic males and females from various high school health clinics. Specimens were tested for C. trachomatis with the three NAATs, and a true-positive result was defined as any two positive NAATs. The C. trachomatis prevalence was 14.8% (75 of 506 samples). Of the 75 urine samples defined as true positives, LCx detected 72, ProbeTec 72, and AC2 detected 75. The sensitivities of LCx, ProbeTec, and AC2 for C. trachomatis detection were 96.0, 96.0, and 100%, and the specificities were 99.1, 100, and 98.8%, respectively. Four of five samples that were positive with AC2 and negative with LCx and ProbeTec were found to be positive with an alternative target TMA-based NAAT, APTIMA C. trachomatis, suggesting that they may have been true positives. Two of four uniquely positive LCx samples available for subsequent testing were both found to be positive by Roche PCR. We found that the LCx, ProbeTec, and AC2 NAATs are highly sensitive and specific methods for the detection of C. trachomatis in urine specimens and can be recommended for noninvasive screening of C. trachomatis in urine.

The effect of urine testing in evaluations of the sensitivity of the Gen-Probe Aptima Combo 2 assay on endocervical swabs for Chlamydia trachomatis and neisseria gonorrhoeae: the infected patient standard reduces sensitivity of single site evaluation

BACKGROUND

The Gen-Probe APTIMA Combo 2 (AC2) assay is a second-generation transcription-mediated amplification assay for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG).

GOAL

The goal of this study was to evaluate AC2 performance of endocervical (cx) swabs for the detection of CT and NG using either a specimen or an infected patient standard.

STUDY DESIGN

In a multicenter clinical study, we compared AC2 with Abbott's ligase chain reaction (LCR) and Roche's polymerase chain reaction (PCR; Amplicor or COBAS) for CT, and we compared AC2 with Abbott's LCR and culture for NG. A total of 1569 females were enrolled in the study; we collected cx and first-catch urine (FCU) specimens.

RESULTS

CT prevalence was 13.3% for cx specimens and 13.7% for FCU specimens. NG prevalence was 8.7% and 7.9% for cx and FCU specimens, respectively. When based only on cx specimens, AC2, LCR, and PCR sensitivities for CT were 99.4%, 95.6%, and 95.6%, respectively. However, cx sensitivity for CT was reduced to 92.1%, 86.6%, and 87.1% for each respective assay when based on both cx and FCU specimen results (infected patient standard). NG sensitivities for AC2, LCR, and culture based solely on cx specimen results were 99.2%, 96.1%, and 85.9%, respectively. Based on infected patient standard, the sensitivities of each respective assay were 98.5%, 93.9%, and 84.0%.

CONCLUSIONS

The infected patient standard reduces the sensitivity of the endocervical evaluation because some infected patients are positive only with FCU. The reduction in sensitivity is greater when testing for CT. Specificities improved slightly, because some unique cx positives, initially classified as false-positive were confirmed by a positive FCU result. Sensitivity of AC2 was higher than LCR, PCR, and culture. Specificity was slightly lower, but discrepant analysis (using alternate TMA targets) of apparent AC2 false-positives showed that 75% to 80% were true-positives.

Genotypic analysis of HIV-1 drug resistance at the limit of detection: virus production without evolution in treated adults with undetectable HIV loads

Human immunodeficiency virus (HIV) production continues in patients receiving highly active antiretroviral therapy (HAART) with undetectable (<50 copies/mL) virus loads. Our initial cross-sectional study showed that this viremia is composed of viruses that lack new resistance mutations to the HAART regimen. Here we describe a longitudinal, clonal genotypic analysis of plasma virus loads in treated adults who had undetectable virus loads. We document a continuous production of virus in 8 HIV-1-infected adults who maintained suppression of viremia for up to 15 months. Using analytical approaches for distinguishing selected resistance mutations from nonselected mutations and polymerase chain reaction errors, we detected no evolution of resistance in the reverse-transcriptase and protease genes. Sporadic resistance mutations were detected in some viral clones that were not selected for subsequently. Thus, in some patients, HAART suppresses replication to a level that does not allow the evolution of drug resistance over a time frame of years.

Determinants of HIV‐1 Load in Subjects with Early and Later HIV Infections, in a General‐Population Cohort of Rakai, Uganda

Human immunodeficiency virus (HIV) type 1 RNA loads were determined for 256 subjects with early (incident) HIV infection and for 1293 subjects with later (prevalent) HIV infection, in a Ugandan cohort. Prevalent infections were classified as latent (0-1 symptoms) and midstage disease (>/=2 symptoms), and deaths were ascribed to acquired immunodeficiency syndrome. Among subjects with incident HIV infection, HIV load did not differ by sex, but, among subjects with prevalent HIV infection, it was higher in males than in females. HIV load was highest in subjects (25-29 years old) with incident HIV infection but increased with age in subjects with prevalent HIV infection. Viremia was higher after serconversion than in latency and increased with more advanced disease. Viremia was increased with genital ulcer disease (GUD) in both subjects with incident infection and in those with prevalent infection, and with herpes simplex virus type 2 seropositivity in subjects with incident HIV infection. GUD was consistently associated with higher HIV loads in subjects with incident and those with prevalent HIV infection, suggesting that treatment of GUD might reduce HIV viremia.

Continued production of drug-sensitive human immunodeficiency virus type 1 in children on combination antiretroviral therapy who have undetectable viral loads

Highly active antiretroviral therapy (HAART) can suppress plasma human immunodeficiency virus type 1 (HIV-1) levels to below the detection limit of ultrasensitive clinical assays. However, HIV-1 persists in cellular reservoirs, and in adults, persistent low-level viremia is detected with more sensitive assays. The nature of this viremia is poorly understood, and it is unclear whether viremia persists in children on HAART, particularly those who start therapy shortly after birth. We therefore developed a reverse transcriptase PCR (RT-PCR) assay that allows genotyping of HIV-1 protease even when viremia is present at levels as low as 5 copies of HIV-1 RNA/ml. We demonstrated that viremia persists in children with plasma virus levels below the limit of detection of clinical assays. Viremia was detected even in children who began HAART in early infancy and maintained such strong suppression of viremia that HIV-1-specific antibody responses were absent or minimal. The low-level plasma virus lacked protease inhibitor resistance mutations despite the frequent use of nelfinavir, which has a low mutational barrier to resistance. Protease sequences resembled those of viruses in the latent reservoir in resting CD4(+) T cells. Thus, in most children on HAART with clinically undetectable viremia, there is continued virus production without evolution of resistance in the protease gene.

Cost-Effectiveness Analysis of Screening Adolescent Males for Chlamydia On Admission to Detention

BACKGROUND

Chlamydia trachomatis infections can lead to serious and costly sequelae. Because chlamydia is most often asymptomatic, many infected youth do not seek testing. Entry to a detention system provides an opportunity to screen and treat many at-risk youth. GOAL The goal of this study was to determine the cost-effectiveness of screening male youth for chlamydia on entry to detention.

STUDY DESIGN

Incremental cost-effectiveness of 3 chlamydia screening strategies was compared for a hypothetical cohort of 4000 male youth per year: 1) universal chlamydia screening using a urine-based nucleic acid amplification test (NAAT), 2) selective NAAT screening of urine leukocyte esterase (LE)-positive urines, and 3) no screening. The model incorporated programmatic costs of screening and treatment and medical cost savings from sequelae prevented in infected males and female partners. The analysis was conducted from the healthcare system perspective.

RESULTS

Chlamydia prevalence in the sampled population of 594 was 4.8%, and the average number of female sexual partners/infected male was 1.6. Universal NAAT screening was the most cost-effective strategy, preventing 37 more cases of pelvic inflammatory disease (PID) and 3 more cases of epididymitis than selective screening and saving an additional 24,000 dollars. The analysis was sensitive to NAAT cost, LE sensitivity, rate of PID development, PID sequelae cost, and number of female partners. Universal screening remained the most cost saving for prevalence as low as 2.8% or higher.

CONCLUSIONS

Universal chlamydia screening of adolescent males on entry to detention was the most cost-effective strategy. Savings are primarily the result of the prevention of PID in recent and future partners of index males. Screening detained male youth using a urine-based NAAT provides a public health opportunity to significantly reduce chlamydia infections in youth at risk for sexually transmitted diseases.

Preference among female Army recruits for use of self-administrated vaginal swabs or urine to screen for Chlamydia trachomatis genital infections

BACKGROUND

Use of self-administered vaginal swabs (SAS) for the detection of Chlamydia trachomatis by nucleic acid amplification tests simplifies specimen collection and transport, especially for women in nonclinical settings.

GOAL

We investigated the preference and comfort level of military women for the collection of SAS, compared with urine, for the diagnosis of genital chlamydial infections.

STUDY DESIGN

During March through August 1999, female Army recruits in basic training at Fort Jackson, South Carolina, were invited to participate in the study. Participants were requested to complete a questionnaire after providing both first-void urine (FVU) and SAS specimens. Participant characteristics, preferences, and comfort levels were assessed using multivariate logistic regression.

RESULTS

From 4496 eligible female recruits, 1403 (31%) completed questionnaires and 1382 provided both specimens; 11.8% (166 of 1403) of participants were infected with chlamydia. The relative sensitivity and specificity of the C. trachomatis Ligase Chain Reaction test on SAS in 1382 matched pairs was 81.1% and 98.6%, respectively, using the test result on urine specimens as the comparison standard. Most of the participants (90.8%) reported that they felt comfortable collecting the FVU specimen, and 69.6% indicated that they felt comfortable collecting SAS. Either specimen collection type received high acceptability at home and in the field, and more women reported that they would collect FVU than reported they would collect SAS in the future (in the field: FVU: 79.4%, SAS: 68.8%, P <0.001); at home: FVU: 90.9%, SAS: 82.9%, P <0.001). When questioned about ease of use, 60.4% of women reported that urine was the easier method. Preferences for SAS were associated with being white and having had sexual risk behaviors in the past 3 months.

CONCLUSION

A study of preferences for urine versus self-administered vaginal swabs for the detection of C. trachomatis in military women showed that women generally found SAS acceptable. SAS should be a feasible alternative to urine collection in situations in which specimen storage or transport is an issue.

Human immunodeficiency virus acquisition associated with genital ulcer disease and herpes simplex virus type 2 infection: a nested case-control study in Rakai, Uganda

To assess the timing of symptomatic genital ulcer disease (GUD) relative to human immunodeficiency virus (HIV) seroconversion, we studied 248 case subjects who underwent HIV seroconversion and 496 HIV-negative control subjects, at 3 interview visits conducted at 10-month intervals: visit 1, before HIV acquisition; visit 2, after seroconversion; and visit 3, 10 months after detection of seroconversion. Odds ratios (ORs) and 95% confidence intervals (CIs), for HIV acquisition, were estimated by logistic regression. HIV load was measured by RNA-polymerase chain reaction, and herpes simplex virus type 2 (HSV-2) serologic testing used HerpeSelect EIA with Western blot confirmation. The OR of HSV-2 seropositivity associated with HIV acquisition was 1.7 (95% CI, 1.2-2.4). Prevalence of GUD was increased among case subjects, at visits 2 (OR, 3.2; 95% CI, 1.9-5.3) and 3 (OR, 2.1; 95% CI, 1.1-3.9). HIV load was increased in HSV-2-seropositive case subjects, compared with that in HSV-2-seronegative subjects, at 5 (P=.04) and 15 (P=.02) months after seroconversion. HIV acquisition is associated with HSV-2 seropositivity, and GUD is increased after seroconversion. HIV load is increased in HSV-2-positive subjects who seroconverted, suggesting a role for treatment of HSV-2 infection in HSV-2-seropositive, dually infected individuals.

Stochastic simulation of the impact of antiretroviral therapy and HIV vaccines on HIV transmission; Rakai, Uganda

OBJECTIVE

To model the effects of antiretroviral therapy (ART) and HIV vaccines on HIV transmission using empirical data from studies in Rakai, Uganda.

DESIGN

A stochastic simulation model estimated HIV incidence, probabilities of transmission per coital act and the reproductive number (R0) with ART and HIV vaccines. Model inputs included Rakai data on HIV transmission probabilities per coital act by HIV viral load, age and gender, and sexual behaviors. The impacts of therapy were derived from US programs, and vaccine assumptions included preventive efficacies ranging from 25 to 75%. Component projection models estimated the numbers of HIV-infected persons over 20 years.

RESULTS

The model incidence [1.57/100 person years (PY)] closely fitted empirical data (1.5/100 PY). Simulations of ART using DHHS treatment guidelines, predicted declines in HIV incidence, but R0 remained > 1.0, and the numbers of HIV-positive persons did not change substantially over 20 years. Preventive vaccines with > 50% efficacy and > 50% population coverage could reduce R0 to < 1.0, and substantially reduce the number of HIV-infected persons over 20 years. Concurrent ART and a preventive vaccine can have substantial impact at lower levels of population coverage and would markedly reduce the HIV infected population over 20 years. However, behavioral disinhibition with increased numbers of sexual partners in either ART or vaccine recipients, increased HIV incidence and diminished intervention impact.

CONCLUSION

ART alone cannot control the HIV epidemic in mature epidemics such as Rakai, and persons in need of therapy will increase over time. ART in combination with a low efficacy vaccine could control the epidemic, if behavioral disinhibition is prevented.

Vaginal swabs are appropriate specimens for diagnosis of genital tract infection with Chlamydia trachomatis

Because self-collected vaginal swabs (VS) are potentially very useful for screening asymptomatic women for Chlamydia trachomatis infection, a multicenter study evaluated that specimen with nucleic acid amplification tests (NAATs). The objective was to determine whether VS are equal to Food and Drug Administration (FDA)-cleared specimens (cervical swabs and first-catch urines [FCU]) for diagnosing genital chlamydial infection. All NAATs then commercially available (October 1996 to October 1999) were used (ligase chain reaction [LCx Probe System; Abbott Laboratories, Abbott Park, Ill.]; PCR [Amplicor; Roche Molecular Systems, Branchburg, N.J.]; and transcription-mediated amplification, [Amplified CT Assay; Gen-Probe Inc., San Diego, Calif.]). NAATs were performed on FCU, urethral, cervical, self- and clinician-collected VS. Sensitivity was compared to isolation using cervical and urethral swabs. Agreement of NAAT results between VS and cervical swabs or FCU was calculated. Specimens from 2,517 15- to 25-year-old asymptomatic women attending clinics at nine different centers were evaluated. Results with self- and clinician-collected VS were equivalent and were at least as good as results with FCU and cervical swabs. Across all sites, summary specificities for all specimens were >99%. Among culture-positive women, NAAT sensitivity with VS (93%) was as high as or higher than NAAT sensitivity with cervical swabs (91%) or FCU (80.6%) or culture of cervical swabs (83.5%). VS are appropriate specimens for diagnosing chlamydial genital tract infection by NAATs. That patients can efficiently collect them offers important benefits for screening programs. It would be beneficial for public health programs if the NAAT manufacturers sought FDA clearance for this specimen.

Analysis of human immunodeficiency virus type 1 gene expression in latently infected resting CD4+ T lymphocytes in vivo

In individuals with human immunodeficiency virus type 1 (HIV-1) infection, a small reservoir of resting memory CD4(+) T lymphocytes carrying latent, integrated provirus persists even in patients treated for prolonged periods with highly active antiretroviral therapy (HAART). This reservoir greatly complicates the prospects for eradicating HIV-1 infection with antiretroviral drugs. Therefore, it is critical to understand how HIV-1 latency is established and maintained. In particular, it is important to determine whether transcriptional or posttranscriptional mechanisms are involved. Therefore, HIV-1 DNA and mRNAs were measured in highly purified populations of resting CD4(+) T lymphocytes from the peripheral blood of patients on long-term HAART. In such patients, the predominant form of persistent HIV-1 is latent integrated provirus. Typically, 100 HIV-1 DNA molecules were detected per 10(6) resting CD4(+) T cells. Only very low levels of unspliced HIV-1 RNA ( approximately 50 copies/10(6) resting CD4(+) T cells) were detected using a reverse transcriptase PCR assay capable of detecting a single molecule of RNA standard. Levels of multiply spliced HIV-1 RNA were below the limit of detection (<50 copies/10(6) cells). Only 1% of the HIV-1 DNA-positive lymphocytes in this compartment could be induced to up-regulate HIV-1 mRNAs after cellular activation, indicating that most of the proviral DNA in resting CD4(+) T cells either carries intrinsic defects precluding transcription or is subjected to transcriptional control mechanisms that preclude high-level production of multiply spliced mRNAs. Nevertheless, by inducing T-cell activation, it is possible to isolate replication-competent virus from resting CD4(+) T lymphocytes of all infected individuals, including those on prolonged HAART. Thus, a subset of integrated proviruses (1%) remains competent for high-level mRNA production after cellular activation, and a subset of these can produce infectious virus. Measurements of steady-state levels of multiply spliced and unspliced HIV-1 RNA prior to cellular activation suggest that infected resting CD4(+) T lymphocytes in blood synthesize very little viral RNA and are unlikely to be capable of producing virus. In these cells, latency appears to reflect regulation at the level of mRNA production rather than at the level of splicing or nuclear export of viral mRNAs.

Sustained high prevalence of Chlamydia trachomatis infections in female army recruits

BACKGROUND

Chlamydia trachomatis infections are prevalent among young sexually active females, have serious sequelae, and are mostly asymptomatic. Screening and treatment of infected females has been demonstrated to prevent sequelae such as pelvic inflammatory disease.

GOAL

To assess prevalence and risk factors for chlamydia infection in US Army female recruits, whether these changed over time, and to examine variables contributing to any observed patterns.

STUDY DESIGN

Prevalence study of 23,010 non-healthcare-seeking female Army recruits enrolled in a chlamydia screening program at Fort Jackson, SC, from January 1996 through June 1999. Each of the 4-year cohorts was examined separately for prevalence and risk factors.

MAIN OUTCOME MEASURES

Urine-based testing for C trachomatis by ligase chain reaction was used to determine prevalence, and questionnaires were used to collect demographic and risk information. State home of record for each recruit was transformed into Public Health reporting region: West, Midwest, South, Northeast, and Territories.

RESULTS

Prevalence for all years was 9.51%, but a progressive increase from 8.51% to 9.92% occurred over the course of study (P=0.018). The proportion of individuals reporting specific risk factors during the 90 days preceding the study generally decreased over time. In a regression model, significant risk factors for infection included black race, age 25 years or younger, home-of-record from the South, being screened during years 3 and 4 of the study, more than one sex partner, a new sex partner, and history of any sexually transmitted disease. Condom use was protective. In another model controlling for age and home-of-record from the South, being screened in years 2, 3, and 4 of the study were significantly predictive for being chlamydia positive.

CONCLUSION

A high and slightly increasing prevalence of C trachomatis infection was observed among young females entering the military over 4 consecutive years. Young age, black race, home-of-record from the South, more than one sex partner, a new sex partner, condom use, and a history of having a sexually transmitted disease were correlates of chlamydia infection. Sustained high rates of C trachomatis infection in this population provide clear justification for a chlamydia control program for young women entering the Army consisting of screening at entry on the basis of age and possibly home-of-record together with continued periodic rescreening.

SUMMARY

A study of 23,010 female Army recruits demonstrated that a high prevalence of C trachomatis was sustained during 4 years of observation. Year of study, young age, and being from the South were significant predictors of infection.

Human immunodeficiency virus-1 RNA levels and CD4 lymphocyte counts, during treatment for active tuberculosis, in South African patients

During 6 months of treatment, we measured human immunodeficiency virus (HIV)-1 virus loads, CD4 T cell counts, and immune activation markers, in 111 HIV-1-infected patients with active tuberculosis (TB). The median virus load (baseline, 5.58 log(10) copies/mL) significantly increased at 1 month (5.71 log(10) copies/mL), then returned to near-baseline levels at 3 months (5.40 log(10) copies/mL) and at 6 months (5.36 log(10) copies/mL). In contrast, the median CD4 counts increased at 1 month (186/mm(3)), at 3 months (238/mm(3)), and at 6 months (239/mm(3)). CD4 counts and virus loads did not change during therapy. Expression of CD38 and HLA-DR remained high throughout treatment, whereas plasma levels of interleukin-6 decreased over time.

Total lymphocyte count and hemoglobin combined in an algorithm to initiate the use of highly active antiretroviral therapy in resource-limited settings

OBJECTIVE

To develop clinical algorithms that improve the sensitivity of surrogate markers to initiate the use of highly active antiretroviral therapy (HAART) in resource-limited settings.

DESIGN

A retrospective evaluation of total lymphocyte counts (TLC) and hemoglobin to predict the CD4 lymphocyte count.

METHODS

A total of 3269 members of the Johns Hopkins HIV observational cohort contributed 22 690 paired observations of CD4 lymphocyte counts and TLC. Two methods were used to evaluate the effect of combining TLC and hemoglobin to predict CD4 cell counts below 200 cells/mm3 before the initiation of HAART in 1451 participants; 55.3% of participants had CD4 cell counts below 200 cells/mm3.

RESULTS

TLC below 1200 cells/mm3 and hemoglobin below 12 g/dl significantly predicted CD4 cell counts below 200 cells/mm3. For TLC alone sensitivity was 70.7% and specificity was 81.7%. For both men and women, we chose a TLC lower cutoff point of 1200 cells/mm3, an upper cutoff point of 2000 cells/mm3, and hemoglobin of 12 g/dl. For men, method I generated sensitivity of 78.0% and specificity of 77.5%. Method II improved specificity to 81.8%. For women, method I increased sensitivity to 85.6% and decreased specificity to 64.1%. Method II improved specificity to 81.4%.

CONCLUSION

TLC below 1200 cells/mm3 were associated with CD4 cell counts below 200 cells/mm3 as in the WHO guidelines, but sensitivity was low. Adding hemoglobin to TLC increased sensitivity, thereby reducing the risk of false-negative results. Our model may serve as a template for the development of algorithms to initiate the use of HAART in resource-limited settings.

Long-term follow-up studies confirm the stability of the latent reservoir for HIV-1 in resting CD4+ T cells

Latent HIV-1 persists in resting memory CD4+ T cells, even in patients receiving highly active antiretroviral therapy (HAART). It has been unclear how stable this latent reservoir is and whether its persistence reflects replenishment by low-level viremia. Here we show that even in treated patients who have had no detectable viremia for as long as 7 years, the reservoir decays so slowly (t(1/2) = 44 months) that eradication is unlikely.

Short report: analysis of anti-malaria immune response during human immunodeficiency virus infection in adults in Kinshasa, Democratic Republic of the Congo

Co-infection of human immunodeficiency virus and malaria is not uncommon in people living in sub-Saharan Africa. Since HIV infection results in immune deficiency, it may alter the ability of HIV patients to mount proper immune responses against malaria parasites. We measured specific malaria antibodies in 47 specimens from 25 couples from Kinshasa, Democratic Republic of the Congo (DRC), according to their HIV status, and investigated probable interaction between malaria and HIV infection. Plasma samples were analyzed for HIV markers (western blot and viral load) and malaria parasite-specific antibody (antibody titer, pattern of antigen recognized by western blotting, and parasite neutralizing antibodies assayed by growth inhibition). No correlation was identified between measured HIV infection status and malaria-specific parameters.

Performance of the APTIMA Combo 2 assay for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in female urine and endocervical swab specimens

The greater sensitivity of nucleic acid amplification tests (NAATs) for Chlamydia trachomatis and Neisseria gonorrhoeae permits the use of urine and other noninvasive specimens, which can increase the reach and decrease the costs of public health screening programs aimed at controlling these infections. This study evaluated the performance of the APTIMA Combo 2 assay, a multiplex assay based on the transcription-mediated amplification reaction, for the simultaneous detection of both pathogens in endocervical swab and urine specimens from females. Combo 2 assay results were compared with patient infected status, which were available by using other commercial NAATs. Sensitivity and specificity for C. trachomatis were 94.2 and 97.6%, respectively, in swabs and 94.7 and 98.9%, respectively, in first-catch urine (FCU). Sensitivity and specificity for N. gonorrhoeae were 99.2 and 98.7%, respectively, in swabs and 91.3 and 99.3%, respectively, in FCU. The assay reliably detected both infections in coinfected patients. The Combo 2 assay can be recommended for use with endocervical swab and urine specimens from females, especially for screening tests for asymptomatic women in sexually transmitted disease surveillance programs. This Food and Drug Administration-cleared assay can be a useful tool in efforts to reduce the prevalence and incidence of C. trachomatis and N. gonorrhoeae infections in sexually active women and to prevent their costly and serious sequelae.

Consistent subtype-specific anti-HIV type 1 T lymphocyte responses in Indian subjects recently infected with HIV type 1

Anti-HIV-1-specific T cell responses in early HIV-1 infection have been found to be important in deciding the course of disease progression. But there are few data concerning nonsubtype B HIV infection. HIV-1 subtype C is the most prevalent subtype in India. HIV-1 Gag-specific T cell responses in 12 Indian subjects with recent HIV-1 infection were characterized by an ELISpot assay at two consecutive visits and their correlation with plasma viral load and CD4(+) T lymphocyte counts was studied. Ten of the 12 subjects demonstrated T cell responses to either one or both Gag B and C peptides, on at least one visit. Five of 10 responders showed a consistent response (response at both visits): 4 exhibited a Gag C-specific consistent response and 1 showed a consistent response to Gag B. The remaining five patients, showing response at only one of the two visits, were considered inconsistent responders. None of the individuals showed a consistent response to both B and C Gag peptides. Marginally significant correlation was observed between consistency of the response and lower plasma viral load (p = 0.062). The subtype-specific Gag C response was also found to be correlated with lower viral load as compared with the response to Gag B (r = -0.336, p = 0.054 for subtype C and r = -0.234, p = 0.13 for subtype B). The data suggest that the patients exhibiting consistent subtype-specific responses to HIV-1 Gag might have better control of viral replication in early HIV infection.

Detection of bacteremia in emergency department patients at risk for infective endocarditis using universal 16S rRNA primers in a decontaminated polymerase chain reaction assay

Prompt definitive diagnosis of acute bacterial endocarditis in febrile injection drug users (IDUs) remains problematic because of delays associated with blood culture. Rapid detection of bacteremia by polymerase chain reaction (PCR) by use of "universal" primers has been hampered by background bacterial contamination. Broad-range eubacterial primers selected from the 16S rRNA gene were used in a PCR assay coupled with a simple pre-PCR decontamination step. All PCR reagents were pretreated with the restriction enzyme AluI, which has multiple digestion sites in the amplicon but none in the primer sets. When 4 different bacterial species were spiked into healthy human blood specimens, the assay identified each pathogen with an analytic sensitivity of 5 bacteria/PCR reaction. A clinical trial with 51 febrile IDUs revealed that PCR had a sensitivity and specificity of 86.7% and 86.9%, respectively, versus blood culture. Importantly, all (8/8) patients with blood culture-positive infective endocarditis were determined to be positive by PCR. This assay provides a promising diagnostic for rapid identification of bacteremia, particularly valuable in acute care settings.

Screening for HIV infection in high-risk communities by urine antibody testing

OBJECTIVES

To evaluate the effectiveness of urine screening to detect HIV-infected individuals in high-prevalence communities.

METHODS

Urine HIV testing was performed at 16 discrete events and four ongoing testing sites in Baltimore communities with a high incidence of HIV infection. When possible, positive urine test results were confirmed by blood testing. In addition, we attempted to obtain blood samples from subjects who reported a possible exposure to HIV but did not have a positive urine test.

RESULTS

From February 1998 to August 2001, we screened 1718 persons. Overall, 210 persons (12%) were HIV-positive, of whom 169 (80%) had never previously tested positive; 87% of those who tested positive received their results, and most were referred for medical care.

CONCLUSIONS

Urine-based screening for HIV infection in high-prevalence inner city communities can be an effective tool for identifying and treating infected persons who are unaware of their infection.

Rapid disease progression in human immunodeficiency virus type 1-infected seroconverters in India

To determine if the early immunological and virological events of HIV infection are unique in a setting with limited access to health care and HIV-1 subtype C infection, we undertook a prospective cohort study to characterize the early natural history of HIV viral load and CD4(+) T lymphocyte counts in individuals with recent HIV seroconversion in India. CD4(+) T lymphocyte counts were prospectively measured for up to 720 days in 46 antiviral drug-naive persons with very early HIV infection, documented by HIV antibody seroconversion. HIV viral RNA levels were measured subsequently on reposited plasma samples from these same time points. The median viral load "set point" for Indian seroconverters was 28,729 RNA copies/ml. The median CD4(+) cell count following acute primary HIV infection was 644 cells/mm(3). Over the first 2 years since primary infection, the annual rate of increase in HIV viral load was +8274 RNA copies/ml/year and the annual decline in CD4 cell count was -120 cells/year. Although the viral "set point" was similar, the median trajectory of increasing viral load in Indian seroconverters was greater than what has been reported in untreated HIV seroconverters in the United States. These data suggest that the more rapid HIV disease progression described in resource-poor settings may be due to very early virological and host events following primary HIV infection. A rapid increase in viral load within the first 2 years after primary infection may have to be considered when applying treatment guidelines for antiretroviral therapy and opportunistic infection prophylaxis.