Mitchell S. Pate

The rapid test paradox: when fewer cases detected lead to more cases treated: a decision analysis of tests for Chlamydia trachomatis.

BACKGROUND AND OBJECTIVES Screening tests for detection of Chlamydia trachomatis include those processed in laboratories and those designed to be processed at the point of care. The latter tests can yield results at the time of the initial patient visit, but most available lab-processed tests have greater sensitivity. In settings where a proportion of patients do not return for treatment after positive test results, the less sensitive rapid tests could lead to the treatment of more patients and be more cost-effective. GOAL OF THIS STUDY To determine the situations, if any, in which a rapid test might be more cost-effective and treat more infections than lab-based tests. STUDY DESIGN A decision analysis framework was used to compare one point-of-care test (the BioStar Chlamydia OIA) with two lab-based tests (cell culture and the polymerase chain reaction [PCR] assay). It was assumed that all women in the model would be screened. Variables included in the analysis were the prevalence, test sensitivity and specificity, the probability of developing pelvic inflammatory disease after treated and untreated chlamydial infections, and the likelihood that patients would wait for rapid test results or return to the facility for treatment. RESULTS The rapid test treated more cases of infection than the PCR alone if the return rate was less than 65%. A two-test algorithm of the rapid test followed by a PCR test on those initially testing negative identified and treated the greatest number of chlamydial infections and was the most cost-effective at all prevalences above 9%, but this finding was sensitive to the cost estimate for pelvic inflammatory disease. CONCLUSION In settings where patient return for treatment is a problem, point-of-care tests contribute significantly to the detection and treatment of chlamydial infections among women.

Human Male Genital Tract Secretions: Both Mucosal and Systemic Immune Compartments Contribute to the Humoral Immunity

In contrast to numerous studies of female genital tract secretions, the molecular properties of Abs and the magnitude of humoral responses in human male genital tract secretions to naturally occurring Ags and to mucosal and systemic immunizations have not been extensively investigated. Therefore, seminal plasma (SP) collected from healthy individuals was analyzed with respect to Ig levels, their isotypes, molecular forms of IgA, and for the presence of Abs to naturally occurring Ags, or induced by systemic or mucosal immunizations with viral and bacterial vaccines. The results indicated that in SP, IgG and not IgA, is the dominant Ig isotype, and that IgM is present at low levels. IgA is represented by secretory IgA, polymeric IgA, and monomeric IgA. In contrast to the female genital tract secretions in which IgA2 occurs in slight excess, the distribution of IgA subclasses in SP resembles that in plasma with a pronounced preponderance of IgA1. The IgG subclass profiles in SP are also similar to those in serum. Thus, SP is an external secretion that shares common features with both typical external secretions and plasma. Specifically, SP contains naturally occurring secretory IgA Abs to environmental Ags of microbial origin and to an orally administered bacterial vaccine, and plasma-derived IgG Abs to systemically injected vaccines. Therefore, both mucosal and systemic immunization with various types of Ags can induce humoral responses in SP. These findings should be considered in immunization strategies to induce humoral responses against sexually transmitted infections, including HIV-1.

Epigenetic regulation of human telomerase reverse transcriptase promoter activity during cellular differentiation

The human telomerase reverse transcriptase (TERT) gene is transcriptionally inactivated in most differentiated cells but is reactivated in the majority of cancer cells. To elucidate how TERT is inactivated during differentiation, we applied all‐trans retinoic acid (ATRA) to induce the differentiation of human teratocarcinoma (HT) cells and human acute myeloid leukemia (HL60) cells. We first showed that TERT promoter activity decreased rapidly, which preceded a gradual loss of endogenous telomerase activity following ATRA induction. To elucidate the underlying mechanisms of the reduced TERT promoter activity during differentiation, we performed epigenetic studies on the TERT promoter and found a progressive histone hypoacetylation coupled with a gradual accumulation of methylated cytosines in the TERT promoter. We also observed that the TERT promoter was less methylated in pluripotent HT cells than in multipotent HL60 cells throughout a 12‐day differentiation process. This origin‐dependent epigenetic change was also confirmed in histone acetylation studies, indicating that the TERT promoter was more resistant to deacetylation in HT cells than in HL60 cells. Taken together, our results demonstrate synergistic involvement of DNA methylation and histone deacetylation in the down‐regulation of TERT promoter activity that may be dependent on the origin of the cell types, and they add new insight into the way telomerase activity may be regulated during differentiation.

Urethral cytokine and immune responses in Chlamydia trachomatis-infected males.

ABSTRACT Penile urethral swabs collected from PCR-confirmed Chlamydia trachomatis-infected, C. trachomatis-uninfected, and non-C. trachomatis-infected, nongonococcal urethritis-infected males were analyzed for cytokine, total immunoglobulin (Ig), and specific antibody levels by enzyme-linked immunosorbent assay. Differential cellular components of the swab transport medium were also enumerated for the same groups. Although low, the levels of C. trachomatis-specific IgA and IgG antibodies and interleukin 8 cytokine were significantly higher inC. trachomatis-infected individuals. There were no significant differences in the levels of seven additional cytokines evaluated.

High prevalence of Chlamydia trachomatis infections in adolescent females not having pelvic examinations: Utility of PCR-based urine screening in urban adolescent clinic setting

PURPOSE To determine utility of polymerase chain reaction (PCR)-based urine screening for Chlamydia trachomatis in the care of adolescent females in an urban clinic. METHODS Females > or = 15 years of age attending an adolescent clinic were approached consecutively. Each enrollee was interviewed to determine the primary reason(s) for the clinic visit and was queried about genitourinary symptoms. Nonsterile voided urine specimens were tested for C. trachomatis using PCR-based analysis. Endocervical C. trachomatis cultures were obtained from the subjects who had a pelvic examination. Main outcome measures were chlamydia infection rates in clinic attendees whether a pelvic examination was performed or not. RESULTS A total of 315 (99.4%) of 317 patients approached agreed to participate. Overall, 47 (14.9%) patients had positive urine PCR tests. The chlamydia infection rate detected by urine PCR was 22.1% (19 of 86) among those who had pelvic examinations performed and 12.2% (28 of 229) among those who did not (p = .03; odds ratio 2.04; 95% confidence interval 1.02, 4.06). Sixty percent (28 of 47) of chlamydia infections identified during the study period were identified by the urine screening test. CONCLUSION Urine screening was accepted by vast majority of female adolescents attending the clinic irrespective of reason for the clinic visit, and was highly effective in identifying unsuspected C. trachomatis infections, particularly among girls attending the clinic for reasons unrelated to reproductive health care and as an interim screening tool for adolescent family-planning clients.

Laboratory to laboratory variation in Chlamydia trachomatis culture practices

Goal of this Study: To compare laboratory to laboratory variability in methods of cell culture for Chlamydia trachomatis performed by North American research laboratories. Study Design: The authors administered a standardized 54-question survey to laboratories that had published articles in any of three medical journals reporting on the use of cell culture to identify individuals with C. trachomatis infection. Laboratory to laboratory variability in specimen collection, specimen transport conditions, culture methodologies, and criteria for evaluation of culture outcomes was examined. Results: Twenty-five (93%) of 27 laboratories responded to the survey. Only two of 54 questions were answered uniformly by all responding laboratories. All laboratories reported vortexing or sonication of specimens before culture inoculation and centrifugation of inoculated cultures prior to incubation. In contrast, substantial variation was noted in specimen collection devices, specimen transport conditions and times, culture format, culture procedures, and criteria for identifying positive cultures. Conclusion: Although this study did not evaluate the sensitivity of chlamydia cell cultures performed in different laboratories, there was substantial laboratory to laboratory variation in nearly every facet of culture evaluated. Laboratory to laboratory variation in chlamydia cell culture sensitivity likely accounts for part of the substantial variability in published evaluations of the sensitivity of nonculture chlamydia diagnostic tests.

UTILITY OF PCR-BASED URINE SCREENING FOR CHLAMYDIA IN ADOLESCENT CLINIC SETTING: PREVALENCE AMONG FEMALES NOT HAVING INDICATION FOR A PELVIC EXAMINATION: 29

OBJECTIVE: To determine utility of a polymerase chain reaction(PCR) based urine screening for C. trachomatis (CT) in the care of females in an urban adolescent clinic.