BD ProbeTec ET Research Articles

Performance of the BD ProbeTec ET direct detection assay for the analysis of Mycobacterium tuberculosis in respiratory and non-respiratory clinical specimens.

ObjectivesEarly detection of Mycobacterial tuberculosis infection (MTB) is pivotal for the treatment of tuberculosis (TB).BackgroundThis study was performed to evaluate the performance of BD ProbeTec ET direct detection assay (DTB) against the gold standard culture technique for confirmation of MTB infection.MethodsA total of 266 consecutive and non-duplicate clinical specimens for detection of MTB were included in this study. There were 118 respiratory and 148 non-respiratory samples. All samples were tested by microscopy for acid-fast bacillus (AFB), MTB culture and biochemical identification with simultaneous testing by DTB.ResultsA total of 88 samples (33%) were culture-positive for MTB including 39/118 respiratory, 29/99 fluid and 20/49 tissue samples. DTB sensitivity for respiratory samples was 97% and specificity was 96% with a positive predictive value (PPV) of 93% and negative predictive value (NPV) of 99%. Sensitivity of DTB in fluid samples was 80%, specificity 88%, PPV 69% and NPV 93% whereas sensitivity of DTB for tissue samples was 25%, specificity 90%, PPV 63% and NPV 63%. Of the 50 (56.8%) smear-positive samples, DTB sensitivity was 100% for respiratory, 85% for fluid and 100% for tissue samples.ConclusionDTB performed within acceptable limits for the rapid detection of MTB in respiratory samples compared to fluid and tissue specimens.

Poor Performance of the Chlamydia Rapid Test Device for the Detection of Asymptomatic Infections in South African Men: A Pilot Study

Background. To the best of our knowledge, there have been no published reports on the diagnostic performance of the Chlamydia Rapid Test (CRT) Device for male urine samples. We evaluated the performance of the CRT Device when compared with that of the BD ProbeTec ET PCR Assay in a population of asymptomatic men. Methods. The study enrolled 100 men between June and July 2015. From each consenting male, 20–30 mL of urine was collected. Sensitivity and specificity of the rapid test compared to PCR were calculated. All analysis was performed in STATA version 13. Results. All men had valid rapid and PCR test results. The test showed a low sensitivity against PCR (20%) (95% CI 3.7–6.2%); however, an excellent specificity was observed (100%) (one sided 97.5% CI: 96.0–100). Conclusions. This test was not found to be suitable as a screening tool for genital Chlamydia infections in men. Our findings emphasize the need for more sensitive POC tests to be developed since the current approach for the management of STIs in Africa is confounded by poor sensitivity and specificity resulting in many infected individuals not being treated.

Five Years' Evaluation of the BD ProbeTec System for the Direct Molecular Detection of Mycobacterium tuberculosis Complex in Respiratory and Nonrespiratory Clinical Samples.

In this study, Mycobacterium tuberculosis complex was detected by BD ProbeTec ET system in 4716 respiratory and 167 nonrespiratory samples [mostly (98%) smear negative). Sensitivity, specificity, positive and negative predictive values were 81.8%, 98.3, 85.1 and 97.9 for respiratory and 100%, 96.2, 64.7 and 100, for nonrespiratory samples, respectively. Among 149 (3.1%) ProbeTec DTB positive and culture negative samples, 72 (65 respiratory and seven nonrespiratory) (48.3%) were recovered from the patients who were evaluated as having TB infection. The system has been found as useful in early diagnosis of tuberculosis infection in association with the clinical, radiological and histopathological findings.

Comparison of Culture, Real-Time DNA Amplification Assay and Ehrlich-Ziehl-Neelsen for Detection of Mycobacterium tuberculosis.

Mycobacterium tuberculosis is still a substantial health problem universally. Although culture is the gold standard method, reliable, rapid and new methods are required for effective struggle with disease. We retrospectively compared the results of Ehrlich-Ziehl-Neelsen (EZN) stain and real-time DNA amplification assay (BD ProbeTec ET system) with culture. Retrospective study. A total of 703 samples, 182 pulmonary and 521 extra pulmonary, collected from 630 patients between May 2008 and February 2011 were evaluated. Culture was considered the gold standard. For pulmonary specimens, sensitivity, specificity, positive predictive and negative predictive values of BD ProbeTec ET and EZN were calculated to be 100%, 98.8%, 87.5%, 100% and 71.4%, 98.8%, 83.3%, 97.6%, respectively. For extra pulmonary specimens, sensitivity, specificity, positive predictive and negative predictive values of BD ProbeTec ET and EZN were calculated to be 80%, 98.7%, 76.9%, 98.9% and 24%, 98.3%, 42.8%, 96.2%, respectively. According to these results, we suggest that the BD ProbeTec ET system is more reliable than EZN. In addition, the BD ProbeTec ET system produces faster results. Based upon these results, we consider that the BD ProbeTec ET system may be employed in the diagnosis of M. tuberculosis.

Bacterial infections of the lower genital tract in fertile and infertile women from the southeastern Poland

The objective of the study was to investigate the detection rates of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Gardnerella vaginalis, Escherichia coli, Streptococcus agalactiae and Enterococcus faecalis, showing no clinical signs of an ongoing, acute inflammatory state of the vagina and/or the cenrvix, in fertile and infertile women. The study encompassed 161 women, including 101 women treated for infertility and 60 fertile women who had already given birth to healthy children. The material for the presence of C. trachomatis, N. gonorrhoeae, M. genitalium, M. hominis and U. urealyticum was collected from the cervical canal and analyzed by PCR. Furthermore, BD ProbeTec ET system was used to detect C. trachomatis infection. Vaginal swabs were collected for classification of bacterial vaginosis and aerobic vaginitis and assessed according to the Nugent score, as well as by traditional culture methods. U. urealyticum was identified in 9% of the infertile women and in 8% of controls. Presence of M. hominis was demonstrated only in the former (4%) and C. trachomatis only in latter (3%). N. gonorrhoeae and M. genitalium were not found in any of the examined women. The frequency of aerobic vaginitis in both groups was estimated at 12%. There were 7% bacterial vaginosis cases in the study group, and none in the control group (p=0.0096). Despite having no symptoms of an ongoing acute inflammation of the reproductive tract, many women may experience permanent or periodic shifts of equilibrium of the vaginal and/or cervical microflora. BV develops more frequently in infertile patients when compared to the fertile women.

Chlamydia trachomatis in fallopian tubes of women undergoing laparoscopy for ectopic pregnancy

To study whether Chlamydia trachomatis is absent or persists in a latent state in the fallopian tube at the time of laparoscopic salpingectomy for tubal ectopic pregnancy (EP). We examined tissue of the fallopian tubes for the presence of C. trachomatis from women who underwent laparoscopic salpingectomy for EP. Presence or absence of C. trachomatis was assessed using both Probe Tec ET (define Tec and ET please) and real-time polymerase chain reaction (PCR) (Ausdiagnositic STD 6 assays) DNA amplification. Fresh tubal tissue from 17 women with histological confirmation of EP was examined in a hospital setting for the presence of C. trachomatis. The presence of C. trachomatis DNA was confirmed by PCR using a commercial test (BD ProbeTec ET System), and a real-time enhanced PCR able to detect few copies of the organism. Chlamydia DNA was detected in 0/16 tubal specimens, and in one case, the PCR analysis was not possible for presence of inhibitors. We did not find any evidence of latent infection of C. trachomatis in the fallopian tube at the time of laparoscopic salpingectomy for EP in our study. Although the numbers are small, our results suggest that EP can be considered a late complication of the tubal damage resulted from a previous acute Chlamydia infection and that EP may not be related to a latent persistence of Chlamydia in the fallopian tube.

Effectiveness of the BDProbeTec ET system for detection of Mycobacterium tuberculosis complex in sputum and bronchoalveolar lavage specimens

OBJECTIVE: The diagnostic efficacy of the BDProbeTEC ET Mycobacterium tuberculosis (MTB) complex direct detection assay (DTB) performed on bronchoalveolar lavage (BAL) specimens and sputum smears was compared with acid-fast bacilli (AFB) smear microscopy. METHOD: AFB smear microscopy, DTB and culture results of 286 patients with pulmonary tuberculosis were retrospectively reviewed. A total of 120 patients provided expectorated sputum samples, and 166 patients provided BAL specimens. Culture results and clinical diagnosis were used as gold standards. RESULTS: The sensitivity and specificity of the DTB assay in detecting MTB in sputum specimens was significantly higher compared to AFB smear microscopy (83.7% and 82.4%, vs. 75.6%, and 41.2%, respectively). The sensitivity and specificity of the DTB assay in detecting MTB in sputum samples was 77.2% and 100% compared to clinical diagnosis, while AFB smear had a sensitivity and specificity of 70.3% and 26.3%, respectively. Compared to culture, DTB had a sensitivity and specificity of 82.8% and 93.2%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 41.9% and 87.7%, respectively. Compared to clinical diagnosis, DTB had a sensitivity and specificity of 67.2% and 100%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 34.8% and 79.5%, respectively. CONCLUSIONS: The superior performance of the DTB assay relative to AFB smear microscopy makes it a valuable tool to enable early diagnosis of MTB, thereby improving patient care and reducing transmission.

Effectiveness of the BDProbeTec ET system for detection of Mycobacterium tuberculosis complex in sputum and bronchoalveolar lavage specimens

ObjectiveThe diagnostic efficacy of the BDProbeTEC ET Mycobacterium tuberculosis (MTB) complex direct detection assay (DTB) performed on bronchoalveolar lavage (BAL) specimens and sputum smears was compared with acid-fast bacilli (AFB) smear microscopy. MethodAFB smear microscopy, DTB and culture results of 286 patients with pulmonary tuberculosis were retrospectively reviewed. A total of 120 patients provided expectorated sputum samples, and 166 patients provided BAL specimens. Culture results and clinical diagnosis were used as gold standards. ResultsThe sensitivity and specificity of the DTB assay in detecting MTB in sputum specimens was significantly higher compared to AFB smear microscopy (83.7% and 82.4%, vs. 75.6%, and 41.2%, respectively). The sensitivity and specificity of the DTB assay in detecting MTB in sputum samples was 77.2% and 100% compared to clinical diagnosis, while AFB smear had a sensitivity and specificity of 70.3% and 26.3%, respectively. Compared to culture, DTB had a sensitivity and specificity of 82.8% and 93.2%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 41.9% and 87.7%, respectively. Compared to clinical diagnosis, DTB had a sensitivity and specificity of 67.2% and 100%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 34.8% and 79.5%, respectively. ConclusionsThe superior performance of the DTB assay relative to AFB smear microscopy makes it a valuable tool to enable early diagnosis of MTB, thereby improving patient care and reducing transmission.

Comparison of Sputum and Nasopharyngeal Swab Specimens for Molecular Diagnosis of Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila

BackgroundDifferentiation of atypical pathogens is important for community-acquired pneumonia (CAP). In this study, we compared sputum and nasopharyngeal swabs (NPS) for use in detection of Mycoplasma pneumoniae (MP), Chlamydophila pneumoniae (CP), and Legionella pneumophila (LP), using Seeplex PneumoBacter ACE Detection Assay (PneumoBacter; Seegene).MethodsSputum and NPS specimens were collected from patients in 15 hospitals. DNA was extracted from sputum using QIAamp DNA Stool Mini Kit (Qiagen) and from NPS using easyMAG (bioMérieux). Both types of specimens were evaluated by multiplex PCR using PneumoBacter. To determine the diagnostic performance of this assay, sputum samples were also tested using BD ProbeTec ET Atypical Pneumonia Assay (APA; Becton Dickinson).ResultsAmong 217 sputum and NPS, 20 (9.2%), 2 (0.9%), and 0 sputum were positive for MP, LP, and CP, respectively, whereas 8 (3.7%) NPS were positive for MP. The sputum APA test yielded 186, 206, and 204 interpretable results for MP, LP, and CP, respectively. Of these, 21 (11.3%) were positive for MP, 2 (1.0%) were positive for LP, and 0 samples were positive for CP. Compared to APA, the sensitivity and specificity of the sputum assay for MP were 95.2% and 100.0%, respectively, whereas for the NPS assay, these were 38.1% and 93.9%. Sputum testing was more sensitive than NPS testing (P=0.002). For LP and CP diagnosis, PneumoBacter and APA tests agreed 100%.ConclusionsSpecimen type is crucial and sputum is preferred over NPS for simultaneous detection of MP, LP, and CP using multiplex PCR in CAP.

Genital and Extra-genital Screening for Gonorrhoea using the BD Probetec ET System with an In-house PCR Method Targeting the porA Pseudogene as Confirmatory Test

Diagnosing gonorrhoea from extra-genital as well as genital sites is important in managing this sexually transmitted disease. In this study we evaluated a screening procedure for Neisseria gonorrhoeae (GC) from all sample sites in a low-prevalence setting. A total of 69,252 specimens submitted for Chlamydia trachomatis testing were also examined for GC on the BD Viper™ platform using the BD Probetec ET system. In order to avoid false-positive results all GC BD reactive samples were re-tested using a PCR method with the porA pseudogene as target. Using this method we screened 170% more samples for GC than in the previous year, in the same population, and diagnosed more than twice as many GC-positive episodes. The BD system can be used successfully to screen extra-genital as well as genital specimen types for GC in a low-prevalence area if it is combined with a validated confirmatory PCR test.

A Two-Site Analytical Evaluation of the BD Viper System with XTR Technology in Nonextracted Mode and Extracted Mode with Seeded Simulated Specimens

The BD ProbeTec CT Q(x) Amplified DNA Assay and the BD ProbeTec GC Q(x) Amplified DNA Assay (both BD Diagnostics, Sparks, MD) represent two new assays developed for use with the BD Viper System with XTR Technology (BD Diagnostics). These assays were built on the foundation of the former BD ProbeTec ET assays (BD Diagnostics) and its accompanying instrumentation. The study described below compared the new assay format, Extracted Mode, to the former assay format, Nonextracted Mode, with the primary objective of examining and measuring overall time expenditures and efficiency of operation. An 80-142-min reduction in "hands-on" total processing time was observed for the Extracted Mode whether testing urines or swabs. The second objective was to assess the accuracy of performance at low simulated analytical loads for the pathogens Chlamydia trachomatis and Neisseria gonorrhoeae. Performance accuracies for simulated positive and negative urine or swab specimens were calculated to be 99.97% for Extracted Mode and 99.76% for Nonextracted Mode.

P3-S1.30 Successful use of non-invasive self obtained glans/meatal dry FLOQSwabs (COPAN) for CT/NG detection with the BD ProbeTec ET assay in Northern Italy

BackgroundIncreasing Chlamydia trachomatis (CT) rates and ever-present Neisseria gonorrhoeae (NG) infections worldwide in women have led to the consideration of targeted male CT/NG screening programs in order to address the...

P3-S1.31 Comparison of Copan UriSwab with BD ProbeTec urine preservative transport kit for preservation and detection of CT and NG in the ProbeTec assay

BackgroundUrine specimen collection is better accepted by the patients than invasive collection techniques for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG). Self-collection is useful for Sexually Transmitted Infection...

Clinical Evaluation of the BD ProbeTec™ Chlamydia trachomatis Qx Amplified DNA Assay on the BD Viper™ System With XTR™ Technology

This study evaluated the performance of the BD ProbeTec Chlamydia trachomatis Q (CTQ) Amplified DNA Assay on the BD Viper System with XTR Technology in a multicenter study. Specimens were collected at 7 geographically diverse clinical sites from 1538 women and men attending sexually transmitted disease, family planning, and obstetrics and gynecology clinics. There were 1465 evaluable participants, 993 women and 472 men. CTQ assay results from female endocervical, self-collected vaginal, male urethral swab specimens, and male and female neat (unpreserved) urine specimens as well as those obtained using the Urine Preservative Transport (UPT) tube for the CTQ assay were compared with patient-infected status (PIS). PIS was determined based on the combined results from Aptima Combo 2 and BD ProbeTec ET CT Amplified DNA Assay. The sensitivity versus PIS for endocervical, vaginal, and both female urine samples was 91.3%, 96.5%, and 93.0%, respectively. The specificity for the same specimen types was 98.3%, 99.2%, and 99.4% (urine neat) and 99.2% (UPT), respectively. The sensitivity versus PIS for male urethral swabs and both male neat and UPT urine were 92.1% and 98%, respectively, with specificities of 98.4%, 99.2%, and 98.1%, respectively. The CTQ assay demonstrated performance characteristics comparable with other commercially available nucleic acid-based tests such as Aptima Combo 2 and BD ProbeTec ET CT-Amplified DNA assay. Vaginal swabs and male urine specimens, the sample types recommended by the Centers for Disease Control for chlamydia screening, both performed at least as well as other sample types evaluated.

P2-S4.03 Prevalence and risk factors for Chlamydia trachomatis infection among female medical students and women attending family planning clinics in Northern Italy

BackgroundPrevalence and risk data concerning Chlamydia trachomatis CT in Italy is scare. We present a study of the prevalence and predictive risk factors for CT infection by comparing two different...

Performance of a commercial nucleic acid amplification test with extrapulmonary specimens for the diagnosis of tuberculosis

The laboratory diagnosis of tuberculosis (TB) on extrapulmonary specimens is particularly challenging. A number of commercial nucleic acid amplification tests able to detect and identify Mycobacterium tuberculosis (MTB) complex directly from respiratory secretions have been developed, but their use on extrapulmonary samples still calls for validation. The BDProbeTec ET Mycobacterium tuberculosis Complex Direct Detection Assay (DTB) was applied to 918 consecutive extrapulmonary specimens (collected from 863 patients), including 84 gastric aspirates, 145 urine, 136 sterile body fluids, 83 cerebrospinal (CSF) fluids, 237 fine-needle aspirates, 175 pus, 56 biopsies, and two stool specimens. The results were compared with those of acid-fast staining and culture (solid plus liquid media), setting the combination of culture and clinical diagnosis as the gold standard. Ninety-two specimens yielded culture positive for MTB and 24 (smear- and culture-negative) were from patients with TB clinical diagnosis. Of these, 96 were DTB-positive, including all of those from culture-negative TB cases. From 26 specimens, nontuberculous mycobacteria were grown. Two of these specimens were positive by the DTB assay. Finally, of the 776 samples that were smear- and culture-negative for acid-fast bacilli (AFB), collected from patients for whom the diagnosis of TB was excluded, six were DTB-positive. The overall sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of extrapulmonary samples were 82.7, 99.0, 92.3, and 97.8%, respectively. Although, at present, amplification assays cannot replace culture techniques, DTB proved to be rapid and specific for the detection of MTB in extrapulmonary samples.

Abdominal Tuberculosis in Adult: 10-Year Experience in a Teaching Hospital in Central Taiwan

Tuberculosis (TB) is an important communicable disease worldwide. The clinical presentation of abdominal TB often mimics various gastrointestinal disorders and may delay accurate diagnosis. In this study, we conducted a 10-year retrospective study to investigate the clinical manifestations, treatment responses and outcomes of abdominal TB. This retrospective study recruited patients presenting between January 1998 and December 2007; all patients ≥ 18 years of age with a diagnosis of abdominal TB were enrolled. Patient charts were thoroughly reviewed and clinical specimens were processed in the laboratory using the BBL MycoPrep System and BACTEC MGIT 960 Mycobacterial Detection System. Mycobacterium tuberculosis complex was confirmed by acid fast stain and the BD ProbeTec ET System. During the study period, 34 patients were diagnosed with abdominal TB. The mean age was 55+18 years. Fourteen patients (41%) had no risk factors; however, 20 patients (59%) had at least one risk factor. Abdominal pain (94.1%), abdominal fullness (91.2%), anorexia (88.2%) and ascites (76.5%) were the most common presenting symptoms. The peritoneum (88%) was the most commonly involved site. Patients with risk factors such as liver cirrhosis, end-stage renal disease and diabetes mellitus had a higher positive rate of acid-fast stain and mycobacterial culture from abdominal specimens (p = 0.02 and 0.05, respectively). The crude mortality rate was 9% and the attributed mortality rate was 3%. In an endemic area like Taiwan, regardless of whether a patient has risk factors for TB, abdominal TB should be seriously considered as a differential diagnosis when a patient presents with gastrointestinal symptoms and unexplained ascites.

The prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in the endocervical swab specimens of symptomatic, asymptomatic and infertile women in Turkey

To investigate C. trachomatis and N. gonorrhoeae prevalence in three different female populations in Turkey. A total of 370 women, 170 symptomatic, 100 asymptomatic, and 100 infertile, were included. Of the endocervical specimens collected from all women using a Dacron swab, the first one was taken to Stuart's transport medium to culture, while the second one was transferred onto slides to perform direct fluorescent antibody test (DFA) and Gram staining, and the third specimen was used for Becton Dickinson BDProbeTec ET system (BDPT). C. trachomatis was detected in 5.16% of symptomatic, 1.11% of asymptomatic, and 2.15% of infertile women with BDPT. Sensitivity and specificity of the DFA test were 72.73 and 97.85%, respectively. N. gonorrhoeae was detected in 2.42% of symptomatic and in 1.02% of infertile women. N. gonorrhoeae was not detected in any asymptomatic women. In N. gonorrhoeae-positive patients, sensitivity and specificity of culture were 60 and 100%, respectively, while they were 80 and 100% for BDPT. Prevalence of N. gonorrhoeae and C. trachomatis was detected to be low in Turkish women, and the difference between the groups was not significant. Both agents were more prevalent in subjects over 25 years of age.

Distribution of Chlamydia trachomatis ompA genovars and the new variant of C. trachomatis in the Göteborg area, Sweden

The aims of this study were to assess the proportion of the new variant of Chlamydia trachomatis (nvCT) and the distribution of ompA genovars among C. trachomatis-positive patients in the Göteborg area, Sweden. Consecutive urine samples positive for C. trachomatis using BD ProbeTec ET (177 patients, 88 men and 89 women) were collected. An nvCT-specific real-time polymerase chain reaction (PCR) assay was used to investigate the nvCT prevalence. To identify the genovars, a 990-bp ompA DNA segment from 105 specimens was sequenced. Seventeen percent (30/177) of all specimens contained nvCT. Nine different genovars were identified. About 50% were of genovar E, followed by F 16%, G 11%, K 8%, and D 5%, representing about 90% of the specimens in Göteborg. The occurrence of nvCT and the dominance of genovar E in Göteborg is similar to those in other areas of Sweden. To cover about 90% of the C. trachomatis infections in Sweden, the serovars D, E, F, G, and K should be included in future vaccines based on the major outer membrane protein.

Chlamydia Prevalence Among Women and Men Entering the National Job Training Program: United States, 2003–2007

To analyze 5-year prevalence trends in Chlamydia trachomatis infections among high-risk young men and women aged 16 to 24 years entering the National Job Training Program, where universal screening is required. Entrance exams conducted in over 100 National Job Training Program centers from 2003 to 2007 were considered. Women provided cervical specimens tested using either a DNA hybridization probe (PACE 2, Gen-Probe, San Diego, CA) or a strand displacement amplification test (SDA, BD ProbeTec ET, Becton-Dickinson, Sparks, MD). In the absence of a pelvic exam, urine specimens were tested using SDA. PACE 2 testing was performed predominately from 2002 to 2005; from 2005 to 2007, SDA was used. All male testing was conducted using SDA on urine specimens. Chlamydia prevalence trends were assessed for women and men, using logistic regression models. Adjusted odds ratios (AOR), 95% confidence intervals (CI), and P-values were calculated. Approximately 15,000 women and 30,000 men were screened annually for chlamydia. Among both sexes, adjusted prevalence declined significantly from 2003 to 2007. In 2003, crude prevalence among women was 9.9%; in 2007, prevalence was 13.7%. However, after controlling for covariates, including increasingly sensitive tests, the model indicated a significant declining prevalence trend (AOR: 0.95, CI: 0.93-0.97, 4.6% decrease in odds per year). Among men, crude prevalence in 2003 was 8.4%; in 2007, prevalence was 8.3%; after controlling for possible confounding, a significant decline in prevalence was also detected (AOR: 0.98, CI: 0.96-0.99, 1.9% decrease in odds per year). In a relatively stable, high-risk population of young women and men, adjusted chlamydia prevalence declined from 2003 to 2007. Test technology plays a critical role in interpreting rates and should be considered whenever chlamydia rates are examined.