Evaluation of CDC-recommended approaches for confirmatory testing of positive Neisseria gonorrhoeae nucleic acid amplification test results

Pooling Pharyngeal, Anorectal, and Urogenital Samples for Screening Asymptomatic Men Who Have Sex with Men for Chlamydia trachomatis and Neisseria gonorrhoeae

Screening for Chlamydia trachomatis and Neisseria gonorrhoeae at the pharyngeal, urogenital, and anorectal sites is recommended for men who have sex with men (MSM). Combining the three individual-site samples into a single pooled sample could result in significant cost savings, provided there is no significant sensitivity reduction. The aim of this study was to examine the sensitivity of pooled samples for detecting chlamydia and gonorrhea in asymptomatic MSM using a nucleic acid amplification test. Asymptomatic MSM who tested positive for chlamydia or gonorrhoea were invited to participate. Paired samples were obtained from participants prior to administration of treatment. To form the pooled sample, the anorectal swab was agitated in the urine specimen transport tube and then discarded. The pharyngeal swab and 2 ml of urine sample were then added to the tube. The difference in sensitivity between testing of pooled samples and individual-site testing was calculated against an expanded gold standard, where an individual is considered positive if either pooled-sample or individual-site testing returns a positive result. All samples were tested using the Aptima Combo 2 assay. A total of 162 MSM were enrolled in the study. Sensitivities of pooled-sample testing were 86% (94/109; 95% confidence interval [CI], 79 to 92%]) for chlamydia and 91% (73/80; 95% CI, 83 to 96%) for gonorrhea. The sensitivity reduction was significant for chlamydia (P = 0.02) but not for gonorrhea (P = 0.34). Pooling caused 22 infections (15 chlamydia and 7 gonorrhoea) to be missed, and the majority were single-site infections (19/22). Pooling urogenital and extragenital samples from asymptomatic MSM reduced the sensitivity of detection by approximately 10% for chlamydia but not for gonorrhea.

Use of the mtrR Gene for Rapid Molecular Diagnosis of Neisseria gonorrhoeae and Identification of the Reduction of Susceptibility to Antibiotics in Endocervical Swabs

BACKGROUND

Neisseria gonorrhoeae is one of the main etiological agents of sexually transmitted diseases. The asymptomatic course of the infection and its resistance to antibiotics can lead to pelvic inflammatory disease and infertility.

OBJECTIVES

We developed a polymerase chain reaction (PCR) test using the methyltetrahydrofolate homocysteine methyltransferase reductase (mtrR) gene to identify N. gonorrhoeae and detect reduced susceptibility to antibiotics.

MATERIAL AND METHODS

We analysed 250 samples of endocervical exudate from infertile women with a negative diagnosis of N. gonorrhoeae. We designed NGmtr primers to detect N. gonorrhoeae and identify the antibiotic-resistant strain.

RESULTS

Of the 250 samples, 60 (24%) tested positive for N. gonorrhoeae using real-time PCR. Our study was validated using the HO primers and the Seeplex STD6 ACE System, with a 100% correlation. Furthermore, the NGmtr primers are specific for N. gonorrhoeae and not for other species. Additionally, the curves generated by real-time PCR differed between wild and variant strains (10.93%). The dissociation temperatures for the wild and variant strains were 86.5 and 89 °C, respectively.

CONCLUSIONS

The NGmtr primers enabled us to identify N. gonorrhoeae strains with or without reduction of susceptibility to antibiotics. Therefore, this work constitutes a tool that will facilitate the diagnosis of this infection for a low cost and improve patient quality of life.

Genital and Extragenital Gonorrhea and Chlamydia in Children and Adolescents Evaluated for Sexual Abuse

OBJECTIVE

The aim of this study was to describe the use of a nucleic acid amplification test in detecting genital and extragenital Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) in children and adolescents assessed for sexual abuse/assault.

METHODS

The charts of children aged 0 to 17 years, consecutively evaluated for sexual victimization, in emergency department and outpatient settings were reviewed. Data extracted included age, sex, type of sexual contact, anogenital findings, previous sexual contact, toxicology results, and sites tested for NG and CT.

RESULTS

Of the 1319 patients who were tested, 579 were tested at more than 1 site, and 120 had at least 1 infected site. Chlamydia trachomatis was identified in 104 patients, and NG was found in 33. In bivariate analysis, a positive test was associated with female sex, age older than 11 years, previous sexual contact, acute or healed genital injury, drug/alcohol intoxication, and examination within 72 hours of sexual contact. Fifty-one patients had positive anal tests, and 24 had positive oral tests. More than 75% of patients with positive extragenital tests had additional positive tests or anogenital injury. Most with a positive anal (59%) or oral (77%) test did not report that the assailant's genitals came into contact with that site.

CONCLUSIONS

Positive tests for NG and CT in patients evaluated for sexual victimization may represent infection from sexual contact, contiguous spread of infection, or the presence of infected assailant secretions. Relying on patient reports of symptoms, or types of sexual contact, to determine need for testing may miss NG and CT infections in patients evaluated for sexual victimization.

Stability Studies on Dry Swabs and Wet Mailed Swabs for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Aptima Assays

The Aptima Combo 2 (AC2) and Aptima CT (ACT) (Hologic Inc., San Diego, CA) are nucleic acid amplification tests (NAATs) that detect Chlamydia trachomatis AC2 also detects Neisseria gonorrhoeae Storage and temperature conditions may impact the utility of NAATs in some settings and screening programs. We evaluated specimen stability for use beyond the Aptima package insert specifications for temperature and duration of storage (between 2°C and 30°C and 60 days, respectively) in two studies: (i) dry C. trachomatis-seeded swabs were used with ACT after storage at 4°C, 23°C, or 36°C for up to 84 days and (ii) swabs seeded with C. trachomatis and N. gonorrhoeae and then placed in transport medium were tested with AC2, after being mailed via the U.S. Postal Service to three different sites. Prolonged storage of samples had no effect, and samples stored at 4°C, 23°C, and 36°C for up to 84 days yielded comparable ACT positivities, although there was a drop in signal intensity for virtually all specimens under all storage/shipping conditions after day 21. In the mailing study, 80%, 52% and 29% of seeded swabs were exposed to temperatures of >30°C during three rounds in transit, and 2% reached temperatures of >40°C. No evidence of signal degradation in the AC2 assay for detection of C. trachomatis or N. gonorrhoeae was observed, although some mailed swabs took more than 5 weeks to reach the laboratory site. These two studies support the potential use of swabs at temperatures above 36°C and storage beyond 60 days and provide confidence regarding this commercially available NAAT for testing of specimens after mailing.

Expansion of Comprehensive Screening of Male Sexually Transmitted Infection Clinic Attendees with Mycoplasma genitalium and Trichomonas vaginalis Molecular Assessment: a Retrospective Analysis

Of 1,493 encounters of males at a sexually transmitted infection (STI) clinic in a community with a high prevalence of STI, Chlamydia trachomatis was detected in 8.7% and Neisseria gonorrhoeae was detected in 6.6%. Additional Trichomonas vaginalis and Mycoplasma genitalium screening found 17.4% and 23.9% of the encounters, respectively, to be positive for STI. STI agents were detected in 13.7% of urine specimens; addition of pharyngeal and rectal collections to the analysis resulted in detection of STI agents in 19.0% and 23.9% of encounters, respectively. A total of 101 (23.8%) encounters of identified STI involved sole detection of M. genitalium Expansion of the STI analyte panel (including M. genitalium) and additional specimen source sampling within a comprehensive STI screening program increase identification of male STI carriers.

Gonorrhoea Diagnostic and Treatment Uncertainties: Risk Factors for Culture Negative Confirmation after Positive Nucleic Acid Amplification Tests

Gonorrhoea incidence has increased substantially in Stockholm during the past years. These increases have coincided with changes in testing practice from solely culture-based to nucleic acid amplification tests (NAAT). Gonorrhoea NAAT is integrated with Chlamydia trachomatis testing and due to opportunistic screening for chlamydia, testing prevalence for gonorrhoea has increased substantially in the Stockholm population. The aim of this study was to examine epidemiological risk-factors for discordant case which are NAAT positive but culture negative. These discordant cases are especially problematic as they give rise to diagnostic and treatment uncertainties with risk for subsequent sequelae. All gonorrhoea cases from Stockholm county during 2011-2012 with at least one positive N. gonorrhoea NAAT test and follow-up cultures were included (N = 874). Data were analysed using multivariate and stratified logistic regression models. Results showed that women were 4-times more likely (OR 4.9; 95% CI 2.4-6.7) than men to have discordant cultures. Individuals tested for gonorrhoea without symptoms were 2.3 times more likely (95% CI 1.5-3.5) than those with symptoms to be discordant. NAAT method and having one week or more between NAAT and culture testing were also indicative of an increased likelihood for discordance. Using NAAT should be based on proper clinical or epidemiological indications and, when positive, followed-up with a culture-based test within one week if possible. Routine gonorrhoea testing is not recommended in low prevalence populations.

Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systemic Review and Meta-Analysis

BACKGROUND

The increases in STI rates since the late 1990s in Canada have occurred despite widespread primary care and targeted public health programs and in the setting of universal health care. More innovative interventions are required that would eliminate barriers to STI testing such as internet-based or mail-in home and community service testing for patients that are hard to reach, who refuse to go for clinician-based testing, or who decline an examination. Jurisdictions such as New Zealand and some American states currently use self-collected sampling, but without the required evidence to determine whether self-collected specimens are as accurate as clinician-collected specimens in terms of chlamydia and gonorrhea diagnostic accuracy. The objective of the review is to compare self-collected vaginal, urine, pharyngeal and rectal samples to our reference standard - clinician-collected cervical, urethral, pharyngeal and rectal sampling techniques to identify a positive specimen using nucleic acid amplification test assays.

METHODS

The hierarchical summary receiver operating characteristic and the fixed effect models were used to assess the accuracy of comparable specimens that were collected by patients compared to clinicians. Sensitivity and specificity estimates with 95% confidence intervals (CI) were reported as our main outcome measures.

FINDINGS

We included 21 studies based on over 6100 paired samples. Fourteen included studies examined chlamydia only, 6 compared both gonorrhea and chlamydia separately in the same study, and one examined gonorrhea. The six chlamydia studies comparing self-collection by vaginal swab to a clinician-collected cervical swab had the highest sensitivity (92%, 95% CI 87-95) and specificity (98%, 95% CI 97-99), compared to other specimen-types (urine/urethra or urine/cervix). Six studies compared urine self-samples to urethra clinician-collected samples in males and produced a sensitivity of 88% (95% CI 83-93) and a specificity of 99% (95% CI 0.94-0.99). Taking into account that urine samples may be less sensitive than cervical samples, eight chlamydia studies that compared urine self-collected verses clinician-collected cervical samples had a sensitivity of 87% (95% CI 81-91) and high specificity of 99% (95% CI 0.98-1.00). For gonorrhea testing, self-collected urine samples compared to clinician-collected urethra samples in males produced a sensitivity of 92% (95% CI 83-97) and specificity of 99% (95% CI 0.98-1.00).

CONCLUSION

The sensitivity and specificity of vaginal self-collected swabs compared to swabs collected by clinicians supports the use of vaginal swab as the recommended specimen of choice in home-based screening for chlamydia and gonorrhea. Urine samples for gonorrhea collected by men had comparably high sensitivity and specificity, so could be recommended as they can be left at room temperature for several days, allowing for the possibility of mail-in home-based testing. In populations that may not go for testing at all, do not have the option of clinical testing, or who refuse a clinical examination, self-collected screening would be a good alternative. We recommend that guidelines on how to self-collect gonorrhea and chlamydia urine, vaginal, rectal and pharyngeal specimens be published.

Forensic medical evaluations of child maltreatment: a proposed research agenda

Physicians play an important role in the forensic evaluation of suspected child abuse and neglect. There has been considerable progress in the medical field, helping distinguish findings related to maltreatment from other conditions or circumstances. Nevertheless, important questions remain. This article covers several of these questions and proposes a research agenda concerning five main topics: sexual abuse, neglect, fractures, abusive head trauma, and physicians work in interdisciplinary settings. The suggestions are hardly inclusive, but offer suggestions the authors think are priorities, and ones that research could reasonably address. By providing some background to gaps in our knowledge, this paper should be of interest to a broader audience than just medical professionals.

Recommendations for the laboratory-based detection of Chlamydia trachomatis and Neisseria gonorrhoeae--2014

This report updates CDC's 2002 recommendations regarding screening tests to detect Chlamydia trachomatis and Neisseria gonorrhoeae infections (CDC. Screening tests to detect Chlamydia trachomatis and Neisseria gonorrhoeae infections-2002. MMWR 2002;51[No. RR-15]) and provides new recommendations regarding optimal specimen types, the use of tests to detect rectal and oropharyngeal C. trachomatis and N. gonorrhoeae infections, and circumstances when supplemental testing is indicated. The recommendations in this report are intended for use by clinical laboratory directors, laboratory staff, clinicians, and disease control personnel who must choose among the multiple available tests, establish standard operating procedures for collecting and processing specimens, interpret test results for laboratory reporting, and counsel and treat patients. The performance of nucleic acid amplification tests (NAATs) with respect to overall sensitivity, specificity, and ease of specimen transport is better than that of any of the other tests available for the diagnosis of chlamydial and gonococcal infections. Laboratories should use NAATs to detect chlamydia and gonorrhea except in cases of child sexual assault involving boys and rectal and oropharyngeal infections in prepubescent girls and when evaluating a potential gonorrhea treatment failure, in which case culture and susceptibility testing might be required. NAATs that have been cleared by the Food and Drug Administration (FDA) for the detection of C. trachomatis and N. gonorrhoeae infections are recommended as screening or diagnostic tests because they have been evaluated in patients with and without symptoms. Maintaining the capability to culture for both N. gonorrhoeae and C. trachomatis in laboratories throughout the country is important because data are insufficient to recommend nonculture tests in cases of sexual assault in prepubescent boys and extragenital anatomic site exposure in prepubescent girls. N. gonorrhoeae culture is required to evaluate suspected cases of gonorrhea treatment failure and to monitor developing resistance to current treatment regimens. Chlamydia culture also should be maintained in some laboratories to monitor future changes in antibiotic susceptibility and to support surveillance and research activities such as detection of lymphogranuloma venereum or rare infections caused by variant or mutated C. trachomatis.

Self-collected versus clinician-collected sampling for sexually transmitted infections: a systematic review and meta-analysis protocol

BACKGROUND

Three meta-analyses and one systematic review have been conducted on the question of whether self-collected specimens are as accurate as clinician-collected specimens for STI screening. However, these reviews predate 2007 and did not analyze rectal or pharyngeal collection sites. Currently, there is no consensus on which sampling method is the most effective for the diagnosis of genital chlamydia (CT), gonorrhea (GC) or human papillomavirus (HPV) infection. Our meta-analysis aims to be comprehensive in that it will examine the evidence of whether self-collected vaginal, urine, pharyngeal and rectal specimens provide as accurate a clinical diagnosis as clinician-collected samples (reference standard).

INCLUSION AND EXCLUSION CRITERIA

Eligible studies include both randomized and non-randomized controlled trials, pre- and post-test designs, and controlled observational studies.

SEARCH STRATEGY

The databases that will be searched include the Cochrane Database of Systematic Reviews, Web of Science, Database of Abstracts of Reviews of Effects (DARE), EMBASE and PubMed/Medline.

DATA COLLECTION AND ANALYSIS

Data will be abstracted independently by two reviewers using a standardized pre-tested data abstraction form. Heterogeneity will be assessed using the Q2 test. Sensitivity and specificity estimates with 95% confidence intervals as well as negative and positive likelihood ratios will be pooled and weighted using random effects meta-analysis, if appropriate. A hierarchical summary receiver operating characteristics curve for self-collected specimens will be generated.

DISCUSSION

This synthesis involves a meta-analysis of self-collected samples (urine, vaginal, pharyngeal and rectal swabs) versus clinician-collected samples for the diagnosis of CT, GC and HPV, the most prevalent STIs. Our systematic review will allow patients, clinicians and researchers to determine the diagnostic accuracy of specimens collected by patients compared to those collected by clinicians in the detection of chlamydia, gonorrhea and HPV.

Retrospective assessment of transcription-mediated amplification-based screening for Trichomonas vaginalis in male sexually transmitted infection clinic patients

Transcription-mediated amplification (TMA) enhances detection of Neisseria gonorrhoeae and Chlamydia trachomatis from rectal and pharyngeal sources. The utility of TMA for detection of Trichomonas vaginalis has recently been described. We report on the performance of TMA for detection of sexually transmitted infection (STI) agents from extraurogenital sources, with a focus on T. vaginalis. Within a 21-month interval, 1,314 consecutive male patient encounters at an STI clinic resulted in collection of 2,408 specimens for C. trachomatis, N. gonorrhoeae, and T. vaginalis TMA screening. A total of 471 encounters were managed with a single specimen collection (94.9% urine), with 12.7% positive for at least one STI agent. This detection percentage increased to 14.4% with collection of specimens from two sources and to 20.3% with collection from three sources (P = 0.03 versus single-source sampling). A total of 44.4% of encounters were managed by collection of urine and pharyngeal specimens and 19.1% by the addition of a third (rectal) collection. While procurement of urine and rectal specimens resulted in greater detection of C. trachomatis (6.1% and 11.3% rates, respectively) than of other STI agents, 858 pharyngeal specimens yielded a 2.9% T. vaginalis detection rate compared with 2.1% for N. gonorrhoeae and 1.6% for C. trachomatis. All T. vaginalis pharyngeal detections were confirmed by TMA-based alternative target testing. A total of 38.1% of T. vaginalis-positive pharyngeal specimens were derived from symptomatic patient encounters. A total of 85.7% of males with T. vaginalis-positive pharyngeal collections indicated strictly heterosexual preference. Additional specimen source sampling is necessary to make STI screening comprehensive. Incorporation of extraurogenital sources into assessment for T. vaginalis detection may identify additional symptomatic and asymptomatic male STI carriers.

Use of APTIMA Combo 2: the experience of a child advocacy center

The Centers for Disease Control and Prevention recommends nucleic acid amplification testing for chlamydia and gonorrhea in sexually abused girls. No studies describe performance of APTIMA Combo 2 Assay with second target confirmation on the same testing platform. This nucleic acid amplification testing is evaluated within a large child advocacy center. Girls 3 to 18 years, 35% of whom reported consensual sexual activity, were prospectively tested by APTIMA Combo 2 on urine/vaginal swabs and by vaginal culture. A case of infection was defined as positive culture or positive urine or vaginal swab nucleic acid amplification testing with second target confirmation. Sensitivity of APTIMA Combo 2 on urine was found to be superior to vaginal culture and comparable to APTIMA Combo 2 on vaginal swabs for both infections. APTIMA Combo 2 on urine is less invasive, and its use may be preferred in this traumatized population.

Comparison of the BD Viper System with XTR Technology to the Gen-Probe APTIMA COMBO 2 Assay using the TIGRIS DTS system for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens

BACKGROUND

Performances of the BD ProbeTec Chlamydia trachomatis (CT)/Neisseria Gonorrhoeae (GC) Q(x) Amplified DNA Assay reagents on a BD Viper System with XTR Technology and APTIMA COMBO 2 Assay reagents on a TIGRIS DTS platform, for detection of both CT and GC were compared.

METHODS

A total of 1018 first-void urine specimens were tested for the presence of CT and GC DNA using the 2 assays.

RESULTS

CT was detected in 143 specimens (14%). Eight specimens exhibited discordant results, and they were divided equally between the 2 assays. Based on the original results, the overall agreement for CT was 99.2%, with 97.1% and 99.5% in agreement with positive and negative specimens, respectively. Cohen's Kappa was 0.967. GC was detected in 27 specimens (2.6%). Two specimens exhibited discordant results, and they were divided equally between the 2 assays. Based on the original results, the overall agreement was 99.8%, with 96.2% and 99.9% in agreement for positive and negative specimens, respectively. Cohen's Kappa was 0.961.

CONCLUSIONS

There was a high level of agreement between the systems for both CT and GC detection.

Self-collection of specimens for nucleic acid-based diagnosis of pharyngeal, cervicovaginal, urethral, and rectal Neisseria gonorrhoeae and Chlamydia trachomatis infections

Commercially available nucleic acid amplification tests (NAATs) for Neisseria gonorrhoeae and Chlamydia trachomatis detection allow for self-collection including home-based collection from multiple anatomic sites such as the urethra, cervicovagina, rectum, and pharynx. Verification studies need to be done prior to processing pharyngeal and rectal specimens. We review specimen collection and test characteristics of NAATs at different anatomical sites.

Molecular Diagnosis of Sexually Transmitted Chlamydia trachomatis in the United States

Chlamydia, with its Chlamydia trachomatis etiology, is the most common bacterial sexually transmitted infection in the United States and is often transmitted via asymptomatic individuals. This review summarizes traditional and molecular-based diagnostic modalities specific to C. trachomatis. Several commercially available, FDA-approved molecular methods to diagnose urogenital C. trachomatis infection include nucleic acid hybridization, signal amplification, polymerase chain reaction, strand displacement amplification, and transcription-mediated amplification. Molecular-based methods are rapid and reliable genital specimen screening measures, especially when applied to areas of high disease prevalence. However, clinical and analytical sensitivity for some commercial systems decreases dramatically when testing urine samples. In vitro experiments and clinical data suggest that transcription-mediated amplification has greater analytical sensitivity than the other molecular-based methods currently available. This difference may be further exhibited in testing of extragenital specimens from at-risk patient demographics. The development of future molecular testing could address conundrums associated with confirmatory testing, medicolegal testing, and test of cure.

Trichomonas vaginalis transcription-mediated amplification-based analyte-specific reagent and alternative target testing of primary clinical vaginal saline suspensions

Following wet mount analysis, 255 vaginal saline suspensions were aliquoted to lysis medium for transcription-mediated amplification (TMA)-based Trichomonas vaginalis analyte-specific reagent testing (ASR) (Gen-Probe, San Diego, CA). Specimens with visible T. vaginalis were then refrigerated, with additional aliquoting at later intervals. Twenty-four wet mount-positive specimens (9.4%) yielded a median luminescent value (x1000, relative light unit [RLU]) of 4736. In contrast, RLU ranged from 1 to 21 following ASR of 204 wet mount-negative specimens. Twenty-seven wet mount-negative specimens (10.5%) were positive by ASR and subsequently positive via T. vaginalis alternative target TMA (Gen-Probe). Discrepancies were additionally resolved by demonstration of T. vaginalis nucleic acid from a separate endocervical collection. T. vaginalis nucleic acid was detectable following prolonged storage, following minimal incubation in lysis medium, and from low-volume aliquots of sparsely populated specimens. T. vaginalis ASR adequately detects T. vaginalis from vaginal saline suspension aliquots, providing a simple specimen alternative for a highly sensitive laboratory diagnosis of trichomoniasis.

Diagnosis, management and prevalence estimation of gonorrhoea: influences of Aptima Combo 2 assay with alternative target confirmation

Case-notes and laboratory data were retrospectively reviewed for influences of dual testing by Aptima Combo 2 (AC2) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) on the diagnosis, management and prevalence estimation of gonorrhoea in the genitourinary (GU) medicine clinic and community. NG positives by AC2 were confirmed by Aptima Gonococcus assay. Unconfirmed positives were rare. Our study showed that in the GU medicine clinic, AC2 detected about 20% extra cases of NG beyond culture. For best standard of care, NG culture and microscopy are still required in some patients to ensure that treatment is rapid and appropriate. Compared to self-referral at the GU medicine clinic, community tests made a substantial contribution to the overall number of NG cases found (40 community versus 35 Macclesfield GU medicine clinic). The ratio of female to male NG cases found was significantly higher (P = 0.002) in the community (13 M, 27 F) than at the GU medicine clinic (25 M, 10 F). In the community, over 60% of NG infections occurred in chlamydia-negative patients. The overall prevalence of NG in the GU medicine clinic was 1.3%, the true prevalence being much lower at 0.9% on primary test. Prevalence in the community was 0.4%. Data from dual testing in the community can clarify NG prevalence beyond the existing KC60 (sexually transmitted infections) reports.

Performance of three nucleic acid amplification tests for detection of Chlamydia trachomatis and Neisseria gonorrhoeae by use of self-collected vaginal swabs obtained via an Internet-based screening program

Use of self-obtained vaginal specimens processed by nucleic acid amplification tests (NAATs) has significantly increased the utilization of nontraditional locations for Chlamydia trachomatis and Neisseria gonorrhoeae screening programs. One important emerging source of such venues includes home-based self-sampling kits available via the Internet. The objective of our study was to evaluate the performance of three commercially available NAATs (Becton-Dickinson ProbeTec SDA, Gen-Probe Aptima Combo2 TMA, and Roche Amplicor PCR) for detection of C. trachomatis and N. gonorrhoeae in vaginal samples obtained via an Internet-based screening program. From July 2004 to August 2005, 500 self-collected vaginal swabs were tested for C. trachomatis and N. gonorrhoeae by using all three NAATs. Another 500 samples were collected between August 2005 and November 2007 and tested by ProbeTec and Combo2; PCR testing was discontinued due to low specificity for N. gonorrhoeae. All tests were conducted according to the manufacturers' procedures; the "gold standard" for an infected C. trachomatis or N. gonorrhoeae patient was defined as > or = 2 positive NAAT results. Of the first 500 swabs submitted, 46 were C. trachomatis infected (9.2%) and 5 were N. gonorrhoeae infected (1.0%), and 3 of these were coinfected (0.6%). All C. trachomatis and N. gonorrhoeae Combo2-positive/ProbeTec-negative samples were confirmed as true positives by an alternative NAAT. For C. trachomatis, ProbeTec, Combo2, and PCR had sensitivities of 82.6%, 100%, and 100%, with specificities of 100%, 100%, and 99.3%, respectively. For N. gonorrhoeae, ProbeTec, Combo2, and PCR had sensitivities of 80%, 100%, and 100%, with specificities of 100%, 100%, and 98.8%, respectively. Of the total 1,000 swabs submitted, 92 were C. trachomatis infected (9.2%) and 15 were N. gonorrhoeae infected (1.5%), and 7 of these were coinfected (0.7%). There were no ProbeTec-positive/Combo2-negative samples. For C. trachomatis, ProbeTec and Combo2 had sensitivities of 81.5% and 100%, with specificities of 100% and 100%, respectively. For N. gonorrhoeae, ProbeTec and Combo2 had sensitivities of 80% and 100%, with specificities of 100% and 100%, respectively. Overall, ProbeTec had 17 C. trachomatis false-negative results (1.7%) and 3 N. gonorrhoeae false-negative results (0.3%), while Combo2 had none. Our results were consistent with the sensitivities and specificities stated by the manufacturers. NAATs perform well for detection of chlamydia and gonorrhea with self-obtained vaginal swabs shipped in a dry state to a laboratory. For 1,000 self-collected vaginal swabs tested by NAATs, the sensitivities for C. trachomatis and N. gonorrhoeae for Combo2 were 100% and 100%, while they were 81.5% and 80%, respectively, for ProbeTec. For 500 PCR samples, the C. trachomatis sensitivity was 100% and the N. gonorrhoeae sensitivity was 100%, with specificities of 99.3% and 98.8%, respectively.

Evaluation of self-collected glans and rectal swabs from men who have sex with men for detection of Chlamydia trachomatis and Neisseria gonorrhoeae by use of nucleic acid amplification tests

Self-collected glans and rectal swab specimens from men who have sex with men (MSM) may be appropriate, convenient specimens for testing. We evaluated the use of self-collected swabs for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by a transcription-mediated amplification test (AC2; Aptima Combo 2; Gen-Probe Inc.) and a strand displacement amplification test (SDA; ProbeTec; Becton Dickinson Co.) in MSM seen at the city sexually transmitted disease clinic in San Francisco, CA. For the glans swab specimen, subjects enrolled early in the study rolled a Dacron swab across the meatus three times (method 1). A slightly more invasive procedure was performed later in the study: the subjects inserted the swab 1/4 in. into the urethra, rotated the swab, and then withdrew the swab (method 2). MSM self-collected a rectal swab specimen and also provided first-catch urine (FCU). Additional rectal swab samples were then obtained by the clinician. For the detection of C. trachomatis and N. gonorrhoeae, all swabs were evaluated by AC2 and SDA, FCU was tested by AC2, and the clinician-collected rectal swabs were cultured. A rectal true-positive (TP) result was defined as a culture-positive result for C. trachomatis or N. gonorrhoeae, two or more positive nucleic acid amplification test (NAAT) results, or a single NAAT-positive result confirmed by an alternate amplification method (the Aptima C. trachomatis or N. gonorrhoeae test). A glans TP result was defined as a positive result for FCU, positive results for both glans specimens (one tested by AC2 and one tested by SDA), or a positive result for a single glans specimen confirmed by an alternate amplification method. The prevalence rates of C. trachomatis and N. gonorrhoeae by testing of FCU were 6.8% (60/882 specimens) and 12.2% (108/882 specimens), respectively. Mixed results were obtained with the glans swab: N. gonorrhoeae detection by AC2 and SDA (method 1) had the best performance (sensitivities, >92%) with samples from a population with a higher prevalence of infection, but their performance for the detection of C. trachomatis was poor and varied by collection method (sensitivities, 56 to 68%). The prevalence rates of C. trachomatis and N. gonorrhoeae in the rectum were 7.3% (66/907 specimens) and 9.4% (83/882 specimens), respectively. The sensitivities of the tests with self-collected and clinician-collected rectal swab specimens were comparable (for C. trachomatis, 41% and 44%, respectively, by SDA and 82% and 71%, respectively, by AC2; for N. gonorrhoeae, 77% and 68%, respectively, by SDA and 84% and 78%, respectively, by AC2). AC2 and SDA were far superior to culture for the detection of C. trachomatis and N. gonorrhoeae in the rectum, with both tests detecting at least twice as many infections. While we found self-collected rectal swabs from MSM to be valid specimens for testing, the sensitivities of the tests with glans swab specimens were disappointing except for those from patients with symptomatic N. gonorrhoeae infections. Self-collected glans swab specimens may not be appropriate for the detection of C. trachomatis or for the detection of N. gonorrhoeae in low-risk or asymptomatic patients by AC2 and SDA, and we would not recommend their use on the basis of our results. Further studies are needed.

[Update on the epidemiology, diagnosis and treatment of sexually-transmitted infections]

In the last decade, cases of sexually-transmitted infections (STIs) have progressively increased in Europe. The reasons for this increase are unclear, but may involve changes in social behavior, migration and international travel, coupled with the emergence of risk groups that have not been taken into sufficient consideration to date. The routine use of molecular diagnostic techniques for many of these infections has solved many problems of sensitivity and the suitability of samples for microbiological diagnosis: non-invasive samples can be used, which has undoubtedly contributed to the increase in the number of cases. Moreover, molecular methods have also been introduced for antibiotic and antiviral susceptibility testing, as well as for molecular characterization of clinical isolates. All of these factors, together with the approval of the vaccine against the human papillomavirus, have changed the landscape of STIs across Europe.