Max Chernesky

Vaginal swabs are the specimens of choice when screening for chlamydia trachomatis and Neisseria gonorrhoeae : Results from a multicenter evaluation of the APTIMA assays for both infections

Background: Vaginal swabs were recently U.S. Food and Drug Administration-cleared for detecting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) using Gen-Probe Incorporated’s APTIMA COMBO2 Assay (AC2). We assessed the APTIMA CT Assay (ACT) for CT, APTIMA GC Assay (AGC) for GC, and AC2 for both organisms using patient- and clinician-collected vaginal swabs. Method: Women attending family planning, obstetrics and gynecology, or sexually transmitted disease (STD) clinics had first-catch urines (FCUs), patient-collected vaginal swabs, clinician-collected vaginal swabs, and endocervical swabs tested by ACT, AGC, and AC2. A second endocervical swab and FCU were tested using BD ProbeTec (Becton Dickinson) for CT and GC. We calculated sensitivity and specificity using vaginal swabs to detect CT and GC. Results: Of 1464 subjects enrolled, 180 had CT and 78 GC. ACT sensitivities and specificities for patient-collected vaginal swabs were 98.3% and 96.5%, respectively; for clinician-collected vaginal swabs, 97.2% and 95.2%, respectively. AGC sensitivities and specificities for patient-collected vaginal swabs were 96.1% and 99.3%, respectively; for clinician-collected vaginal swabs, 96.2% and 99.3%, respectively. AC2 results were similar. If an FCU tested positive for CT or GC, >94% of matching vaginal swabs were positive. Positive endocervical swabs showed slightly less concordance (>90% and >88%, respectively). More infected patients were identified using vaginal swabs than FCUs. With AC2, 171 CT-infected patients were identified using FCUs and 196 using patient-collected vaginal swabs. This difference was more pronounced for CT than for GC. Conclusions: Vaginal swab specimens allowed sensitive and specific detection of CT and GC in the APTIMA assays. Vaginal swabs identified as many infected patients as endocervical swabs and more than FCUs, and may well be the specimen of choice for screening.

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.

Women find it easy and prefer to collect their own vaginal swabs to diagnose Chlamydia trachomatis or Neisseria gonorrhoeae infections.

Background: Self-collected specimens can be used to screen asymptomatic women for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC). We surveyed women’s opinions on ease and preferences as to sampling after collecting their own vaginal swab and urine and a physician collection of vaginal swab and cervical swab. Methods: In 7 North American cities, a questionnaire was used for women after they participated in a clinical trial of nucleic acid amplification testing of various specimens. A total of 1090 women consenting to gynecologic sampling for CT and GC (82% of those sampled) volunteered to complete the survey. We analyzed the data for ease of self-collection and preferences for a vaginal swab, urine, or cervical swab. Results: The average age was 26.6 years; 59.6% were black, 25.5% white, 11% Hispanic, 1.9% Asian, and 2% unknown. Thirty-five percent had more than one sex partner in the past 6 months, 84.9% had been previously tested for a sexually transmitted infection (STI), and 49.2% had experienced an STI. A total of 90.4% found it very easy to self-collect a vaginal swab. This was not influenced by age, education, or study site. Seventy-six percent preferred a vaginal swab over a pelvic examination, 60% over a urine collection, and 94% indicated that they would be tested more often if a vaginal swab was available. Conclusion: Self-collected vaginal swabs were easy to collect and patients preferred them over urine and cervical swabs.

A Randomized, Controlled Trial of Doxycycline and Rifampin for Patients with Alzheimer's Disease

Objectives: To assess whether doxycycline and rifampin have a therapeutic role in patients with Alzheimers disease (AD).

The accuracy of clinical findings and laparoscopy in pelvic inflammatory disease

The accuracy of clinical diagnosis for pelvic inflammatory disease was determined in 95 women who presented with pelvic pain to primary care physicians and then were referred to gynecologists. Laparoscopy or laparotomy with endometrial biopsy and fimbrial minibiopsy revealed that prevalence of pelvic inflammatory was 46% (44/95) and positive and negative predictive values of gynecologists were 74% (23/31) and 67% (43/64) (p = 0.0002). If histopathologic diagnosis was the standard, clinical accuracies of the gynecologists were no better than chance (p = 0.43), suggesting an expectation bias for visual diagnosis. Laparoscopy had a sensitivity of 50% (12/24) and a specificity of 80% (40/50) for salpingitis if the standard was fimbrial histopathologic diagnosis (p = 0.01). These results support the routine use of laparoscopy, supplemented when negative by endometrial and fimbrial minibiopsy, to accurately diagnose pelvic inflammatory disease.

Tubal factor infertility: an association with prior chlamydial infection and asymptomatic salpingitis.

In 265 Canadian women, with and without tubal factor infertility (TFI), we compared Chlamydia trachomatis cultures of endocervical swabs, endotubal swabs and biopsies, serology, and past history. A history of pelvic inflammatory disease (PID) was absent in 69.2% of TFI women, despite visual evidence of tubal damage. C. trachomatis was not isolated in any of 52 patients with TFI (TFI group), 114 having tubal ligation (STER group), or 99 patients having hysterectomy (HYST group). However, chlamydial antigen was detected with an immunochemical method in 1 of 16 tubal biopsy specimens from TFI women. The prevalence of chlamydial IgM or IgG antibody in serum was significantly higher (P less than 0.0001) in the TFI group (79.1%) than in the other two groups (relative odds, 6.3; 95% confidence interval: 2.5, 16.8). In seropositive (IgG or IgM) subjects, there was a significant (P = 0.003) and strong (relative odds, 5.1; 95% confidence interval: 1.5, 18.1) association between chlamydial IgA antibody and TFI. In women with TFI, there was no significant association between IgM or IgG seropositivity (P = 0.56). or IgA seropositivity (P = 0.53), and a negative history for PID. These findings are consistent with the hypothesis that C. trachomatis is a major cause of TFI following PID, which may or may not be asymptomatic.

Comparison of Flocked and Rayon Swabs for Collection of Respiratory Epithelial Cells from Uninfected Volunteers and Symptomatic Patients

ABSTRACT Significantly more epithelial cells were collected by flocked swabs than by rayon swabs in parallel nasopharyngeal and nasal swabs taken from 16 volunteers. Nasopharyngeal sampling of 61 symptomatic patients also yielded more cells by flocked than rayon swabs, providing better clinical specimens for diagnosis.

Replicate PCR Testing and Probit Analysis for Detection and Quantitation of Chlamydia pneumoniae in Clinical Specimens

ABSTRACT Nucleic acid amplification of clinical specimens with low target concentration has variable sensitivity. We examined whether testing multiple aliquots of extracted DNA increased the sensitivity and reproducibility of Chlamydia pneumoniae detection by PCR. Nested and non-nested C. pneumoniae PCR assays were compared using 10 replicates of 16 serial dilutions of C. pneumoniae ATCC VR-1310. The proportion positive versus theC. pneumoniae concentration was modeled by probit regression analysis. To validate the model, 10 replicates of 26 previously positive patient specimens of peripheral blood mononuclear cells (PBMC), sputum, or nasopharyngeal swabs (NPS) were tested. The proportion of replicates that were positive varied with the concentration of C. pneumoniae in the sample. At concentrations above 5 infection-forming units (IFU)/ml, both nested and non-nested PCR assay sensitivities were 90% or greater. The nested PCR was more sensitive (median detection, 0.35 versus 0.61 IFU/ml; relative median detection, 0.58; 95% confidence interval, 0.31 to 0.99; P = 0.04). In clinical specimens, replicate PCR detected 15 of 26 (nested) versus 1 of 26 (non-nested,P < 0.001). For PBMC specimens, testing 1, 3, or 5 replicates detected 3, 5, or 9 of 10 positive specimens, respectively. Median C. pneumoniae concentrations were estimated at 0.07 IFU/ml for PBMC and at <0.03 IFU/ml for NPS specimens. We conclude that performing 5 or 10 replicates considerably increased the sensitivity and reproducibility of C. pneumoniae PCR and enabled quantitation for clinical specimens. Due to sampling variability, PCR tests done without replication may miss a large proportion of positive specimens, particularly for specimens with small amounts of target C. pneumoniae DNA present.

Association of circulating Chlamydia pneumoniae DNA with cardiovascular disease: a systematic review.

BackgroundChlamydia pneumoniae antigens, nucleic acids, or intact organisms have been detected in human atheroma. However, the presence of antibody does not predict subsequent cardiovascular (CV) events. We performed a systematic review to determine whether the detection of C. pneumoniae DNA in peripheral blood mononuclear cells (PBMC) was associated with CV disease.MethodsWe sought studies of C. pneumoniae DNA detection in PBMC by polymerase chain reaction (PCR) among patients with CV disease or other clinical conditions. We pooled studies in which CV patients were compared with non-diseased controls. We analyzed differences between studies by meta-regression, to determine which epidemiological and technical characteristics were associated with higher prevalence.ResultsEighteen relevant studies were identified. In nine CV studies with control subjects, the prevalence of circulating C. pneumoniae DNA was 252 of 1763 (14.3%) CV patients and 74 of 874 (8.5%) controls, for a pooled odds ratio of 2.03 (95% CI: 1.34, 3.08, P < 0.001). Prevalence was not adjusted for CV risk factors. Current smoking status, season, and age were associated with C. pneumoniae DNA detection. High prevalence (>40%) was found in patients with cardiac, vascular, chronic respiratory, or renal disease, and in blood donors. Substantial differences between studies were identified in methods of sampling, extraction, and PCR targets.ConclusionsC. pneumoniae DNA detection was associated with CV disease in unadjusted case-control studies. However, adjustment for potentially confounding measures such as smoking or season, and standardization of laboratory methods, are needed to confirm this association.

High Analytical Sensitivity and Low Rates of Inhibition May Contribute to Detection of Chlamydia trachomatis in Significantly More Women by the APTIMA Combo 2 Assay

ABSTRACT The clinical sensitivity of nucleic acid amplification tests may be determined by analytical sensitivity and inhibitors in patient samples. We established endpoints for detection of propagated Chlamydia trachomatis L2 434, diluted according to swab and urine protocols for APTIMA Combo 2 (AC2), ProbeTec ET (PT), and Amplicor (AMP) assays. AC2 was 1,000-fold more sensitive than PT and 10-fold more sensitive than AMP on mock swab specimens. For urine, AC2 analytical sensitivity was 100-fold greater than those of the other assays. Spiking an aliquot of each clinical-trial sample from 298 women demonstrated inhibition rates in first-void urine (FVU), cervical swabs (CS), and vaginal swabs (VS) of 12.1%, 12.8%, and 10.4% for AMP; 27.2%, 2%, and 2%, for PT; and 0.3%, 1.7%, and 1.3% for AC2. Inhibition of our C. trachomatis spike and the PT or AMP amplification controls from the manufacturers showed less than 50% correlation. Using an infected-patient reference standard (a specimen positive in at least two tests or a single test positive in two of three samples) in AC2, the VS identified 68/69 (98.6%) infected women compared to CS (89.9%) or FVU (81.2%). Significantly fewer women were identified by PT (65.2%, 63.8%, and 66.7%) or AMP (65.2%, 59.4%, and 56.5%) with the three specimens. By individual specimen type, AC2 confirmed virtually all PT- and AMP-positive specimens, but rates of AC2 confirmation by AMP or PT ranged from 62.9 to 80.3%. The AC2 test identified significantly more women infected with C. trachomatis (P = 0.001). Vaginal swabs appear to be the specimen of choice for screening.