Joan M. Chow

Vaginal Swabs Are Appropriate Specimens for Diagnosis of Genital Tract Infection with Chlamydia trachomatis

ABSTRACT 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.

Evidence of Human Papillomavirus Vaccine Effectiveness in Reducing Genital Warts: An Analysis of California Public Family Planning Administrative Claims Data, 2007–2010

Because of the rapid development of genital warts (GW) after infection, monitoring GW trends may provide early evidence of population-level human papillomavirus (HPV) vaccine effectiveness. Trends in GW diagnoses were assessed using public family planning administrative data. Between 2007 and 2010, among females younger than 21 years, these diagnoses decreased 35% from 0.94% to 0.61% (P(trend) < .001). Decreases were also observed among males younger than 21 years (19%); and among females and males ages 21-25 (10% and 11%, respectively). The diagnoses stabilized or increased among older age groups. HPV vaccine may be preventing GW among young people.

Chlamydia trachomatis and neisseria gonorrhoeae prevalence and coinfection in adolescents entering selected US Juvenile Detention Centers, 1997-2002

Background: Juvenile detention centers offer public health practitioners an opportunity to gain access to large numbers of adolescents at risk for chlamydia and gonorrhea. Goal: To describe the prevalence and coinfection of chlamydia and gonorrhea among adolescents in 14 US juvenile detention centers from 1997 to 2002. Study: We calculated the prevalence of chlamydia and gonorrhea in males and females, stratified by race/ethnicity, age group, and site. We also calculated the proportion of adolescents with chlamydia that were coinfected with gonorrhea and the proportion of those with gonorrhea that were coinfected with chlamydia. Results: The prevalence of chlamydia was 15.6% in 33,619 females and 5.9% in 98,296 males; gonorrhea prevalence was 5.1% in females and 1.3% in males. Of females with gonorrhea, 54% were coinfected with chlamydia, and 51% of males with gonorrhea were coinfected with chlamydia. Conclusions: Chlamydia and gonorrhea prevalence was very high in females in all project sites. In males, chlamydia prevalence was high in some areas; however, gonorrhea prevalence was substantially lower. These prevalence data justify screening for chlamydia and gonorrhea among female adolescents in juvenile detention centers nationally.

Detection of Chlamydia trachomatis by Nucleic Acid Amplification Testing: Our Evaluation Suggests that CDC-Recommended Approaches for Confirmatory Testing Are Ill-Advised

ABSTRACT We evaluated three CDC-suggested approaches for confirming positive nucleic acid amplification tests (NAATs) for Chlamydia trachomatis: (i) repeat the original test on the original specimen, (ii) retest the original specimen with a different test, and (iii) perform a different test on a duplicate specimen. For approach 1, specimens (genital swabs or first-catch urine [FCU]) initially positive by the Abbott LCx Probe System Chlamydia trachomatis Assay (LCx; Abbott Laboratories), the APTIMA Combo 2 Assay (AC2; Gen-Probe Inc.), the Amplicor CT/NG Assay (PCR; Roche Diagnostics Corp.), or the BD ProbeTec ET System C. trachomatis amplified-DNA assay (SDA; Becton Dickinson Diagnostic Systems) were retested by the same NAAT. In several evaluations, multiple efforts were made to confirm the original positive result. For approach 2, specimens initially positive by SDA and the Hybrid Capture 2 CT-ID DNA Test (HC2; Digene Corp.) were retested by different NAATs (SDA, PCR, AC2, and the APTIMA assay for C. trachomatis [ACT]). For approach 3, duplicate male urethral or cervical swabs were tested by SDA or by both AC2 and ACT. FCU specimens were tested by all three tests. We found that 84 to 98% of SDA, LCx, PCR, and AC2 positive results were confirmed by a repeat test and that 89 to 99% of SDA and AC2 and 93% of HC2 positive results were confirmed by different NAATs, but that some NAATs cannot be used to confirm other NAATs. The use of repeat testing did not confirm 11% of C. trachomatis SDA positive results that could be confirmed by more extensive testing. Doing more testing confirms more positive results; >90% of all positive NAATs could be confirmed.

Screening for Syphilis With the Treponemal Immunoassay: Analysis of Discordant Serology Results and Implications for Clinical Management

BACKGROUND Screening for syphilis with treponemal chemiluminescence immunoassays (CIA) identifies patients with discordant serology who are not identified with traditional screening methods (eg, CIA-positive, rapid plasma regain (RPR)-negative). We sought to describe the clinical characteristics and management of patients with discordant syphilis serology. METHODS From August 2007-October 2007, patients with CIA-positive, RPR-negative serology were tested with the Treponema pallidum particle agglutination assay (TP-PA) at Kaiser Permanente Northern California. Clinical and demographic characteristics, prior syphilis history and CIA index values were compared for CIA-positive, RPR-negative patients according to TP-PA status. RESULTS Of 21,623 assays, 439 (2%) were CIA-positive and 255/439 (58%) were RPR-negative; subsequently, 184 (72%) were TP-PA-positive and 71 (28%) were TP-PA--negative. TP-PA--positive patients were more likely to be male, HIV-positive, homosexual, previously treated for syphilis (57% versus 9%), with higher median CIA index values (9.8 versus 1.6) (all P < .0001). After repeat testing, 7/31 (23%) CIA-positive, RPR-negative, TP-PA--negative patients seroreverted to CIA-negative. CONCLUSIONS TP-PA results in conjunction with clinical/behavioral assessment helped guide the management of patients with CIA-positive, RPR-negative serology. TP-PA-positive patients were both highly likely to have prior syphilis and major epidemiologic risk factors for syphilis. CIA-positive, RPR-negative, TP-PA-negative serology may represent a false-positive CIA in low-prevalence populations.

An observational cohort study of Chlamydia trachomatis treatment in pregnancy

Background and Objectives: Currently, azithromycin is not considered a first-line treatment for Chlamydia trachomatis in pregnant women. We evaluated the use, efficacy, and safety of azithromycin compared with erythromycin and amoxicillin in the treatment of genital chlamydial infection during pregnancy. Methods: This was a retrospective cohort study of pregnant women with genital chlamydial infection. Data on antibiotics prescribed, test-of-cure (TOC) results, and maternal and infant complications were collected from medical records. Results: Of the 277 women in the study sample, 69% were initially prescribed azithromycin, 9% amoxicillin, and 19% erythromycin. Eight-one percent of subjects had a TOC 7 or more days after diagnosis and before delivery. Treatment efficacy, as defined by a negative TOC, was 97% (95% confidence interval [CI], 92.9–99.2) for azithromycin, 95% (95% CI, 76.2–99.9) for amoxicillin, and 64% (95% CI, 44.1–81.4) for erythromycin. The efficacy of azithromycin was significantly higher than erythromycin (P <0.0001). There were no significant differences in efficacy by age, race/ethnicity, concurrent sexually transmitted disease diagnosis, partner treatment, or substance use. Furthermore, there was no difference in complications for women or infants exposed to azithromycin compared with those treated with other regimens. Conclusion: Clinical outcome data from this study population of women and infants support both efficacy and safety of azithromycin for treatment of C. trachomatis in pregnancy.

The fallibility of diagnostic tests for sexually transmitted diseases: the impact on behavioral and epidemiologic studies

Objectives Analysis of sexually transmitted disease (STD) data to identify specific behaviors and risk factors often fails to take into account the misclassification of disease by a less than perfect diagnostic test. The authors consider here how a diagnostic tests performance profile can introduce misclassification and thereby bias measures of association. Methods The authors used hypothetical data relating to diagnostic tests for Chlamydia trachomatis infections and oral contraceptive use to determine odds ratio estimates given a range of sensitivity, specificity, prevalence of infection, and sample size. Results Lower specificity in a diagnostic test can result in an underestimation of a risk factors association with an infection. This bias is particularly severe in low prevalence populations. Use of a diagnostic test with low specificity also will increase the sample size needed to demonstrate the association and, thus, the cost of such surveys. Conclusions Diagnostics tests for sexually transmitted diseases have less than perfect sensitivity and specificity, which affects the validity of analyses of factors associated with sexually transmitted diseases. Analyses done using low prevalence populations and/or small sample sizes may underestimate the magnitude of effect in retrospective studies and clinical trials of behavioral interventions aimed at reducing sexually transmitted disease risk.

Chlamydia trachomatis and Neisseria gonorrhoeae infections among men and women entering California prisons.

OBJECTIVE We estimated the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae infection among newly arriving inmates at 6 California prisons. METHODS In this cross-sectional study in 1999, urine specimens collected from 698 men aged 18 to 25 years and 572 women aged 18 years or older were tested at intake for C trachomatis and N gonorrhoeae using ligase chain reaction. An analysis of demographic and arrest-related correlates of C trachomatis and N gonorrhoeae infection was performed. RESULTS The overall C trachomatis prevalence was 9.9% (95% CI=7.8%, 12.3%) among men aged 18 to 25 years, 8.9% (95% CI = 2.9%, 22.1%) among women aged 18 to 25 years, and 3.3% (95% CI=2.0%, 5.1%) among women overall. Three N gonorrhoeae cases were detected with an overall prevalence of 0.24% (95% CI=0.05%, 0.69%). CONCLUSIONS The prevalence of C trachomatis infection at entry to California prisons, especially among young female and male inmates, was high, which supports routine screening at entry into prison. In addition, screening in a jail setting where most detainees are incarcerated before entry into the prison setting may provide an excellent earlier opportunity to identify these infections and treat disease to prevent complications and burden of infection in this high-risk population.

Patient-delivered partner therapy for chlamydial infections: attitudes and practices of California physicians and nurse practitioners.

Objective: The objective of this study was to examine California clinicians’ use of and attitudes toward patient-delivered partner therapy (PDPT) to treat sexual partners of patients infected with chlamydia. Study Design: In 2002, a stratified random sample of primary care physicians and nurse practitioners completed a mailed, self-administered survey. Weighted frequencies were calculated to assess partner management practices, including PDPT, and attitudes toward PDPT. Multivariate models were constructed to determine independent predictors of PDPT use. Results: Of 708 physicians and 895 nurse practitioners, approximately half (47% and 48%, respectively) reported that they use PDPT usually or always. Over 90% agreed that PDPT protects patients from reinfection and provides better care for patients with chlamydia. However, providers reported concerns that PDPT may result in incomplete care for the partner, may be dangerous without knowing the partner’s medical or allergy history, is an activity the practice may not get paid for, and may get them sued. Obstetrics/gynecology and family practice physicians were more likely than internal medicine physicians to report routine use of PDPT. Concerns about adverse outcomes of PDPT were associated with less PDPT use. Conclusions: Although the proportion of California healthcare providers routinely using PDPT is comparatively high, further study is warranted to examine the circumstances under which this partner management strategy is used.

Sex and age correlates of Chlamydia prevalence in adolescents and adults entering correctional facilities, 2005: implications for screening policy.

Objectives: To evaluate sex and age correlates of chlamydia prevalence in incarcerated populations. Methods: Cross-sectional analysis of chlamydia prevalence by demographic characteristics from incarcerated females and males entering selected juvenile and adult correctional facilities (jails) in the United States in 2005. Results: A total of 97,681 and 52,485 incarcerated persons aged ≥12 years were screened for chlamydia in 141 juvenile and 22 adult correctional facilities, respectively. Overall, chlamydia prevalence was high in females (14.3% and 7.5%) in both juvenile and adult facilities when compared with that in males (6.0% and 4.6%). The chlamydia prevalence was higher in incarcerated females than in incarcerated males for persons ≤35 years, and prevalence was highest among females aged ≤25 years (range, 11.3%–15.6%). In juvenile facilities, prevalence did not steadily increase with age in females (12.8% in 12–14 years, 15.1% in 15–17 years, and 14.3% in 18–20 years) whereas in males prevalence steadily increased with age (2.4% in 12–14 years to 8.7% in 18–20 years). In females and males the highest prevalence in juvenile facilities was in incarcerated blacks (18.4% and 9.6%, respectively). In adult facilities, the prevalence was consistently highest in younger detainees: in females it was 15.6% in 18- to 20-year olds compared with 1.5% in those >40 years; in males it was 8.8% in 18- to 20-year olds compared with 1.4% in those >40 years. Conclusions: The consistently high chlamydia prevalence among females in juvenile facilities and females (≤25 years) in adult facilities supports a screening policy in correctional settings consistent with Centers for Disease Control and Prevention and US Preventive Services Task Force guidelines. Although the prevalence of chlamydia in males is substantial, chlamydia prevalence in females exceeds that of males ≤35 years, and thus screening females for chlamydia in these facilities should take priority over screening males.