William D. LeBar

The daily dynamics of cystic fibrosis airway microbiota during clinical stability and at exacerbation.

BackgroundRecent work indicates that the airways of persons with cystic fibrosis (CF) typically harbor complex bacterial communities. However, the day-to-day stability of these communities is unknown. Further, airway community dynamics during the days corresponding to the onset of symptoms of respiratory exacerbation have not been studied.ResultsUsing 16S rRNA amplicon sequencing of 95 daily sputum specimens collected from four adults with CF, we observed varying degrees of day-to-day stability in airway bacterial community structures during periods of clinical stability. Differences were observed between study subjects with respect to the degree of community changes at the onset of exacerbation. Decreases in the relative abundance of dominant taxa were observed in three subjects at exacerbation. We observed no relationship between total bacterial load and clinical status and detected no viruses by multiplex PCR.ConclusionCF airway microbial communities are relatively stable during periods of clinical stability. Changes in microbial community structure are associated with some, but not all, pulmonary exacerbations, supporting previous observations suggesting that distinct types of exacerbations occur in CF. Decreased abundance of species that are dominant at baseline suggests a role for less abundant taxa in some exacerbations. Daily sampling revealed patterns of change in microbial community structures that may prove useful in the prediction and management of CF pulmonary exacerbations.

Clostridium difficile Ribotype 027: Relationship to Age, Detectability of Toxins A or B in Stool With Rapid Testing, Severe Infection, and Mortality

BACKGROUND Clostridium difficile infection (CDI) can cause severe disease and death, especially in older adults. A better understanding of risk factors for adverse outcomes is needed. This study tests the hypotheses that infection with specific ribotypes and presence of stool toxins independently associate with severity and constructs predictive models of adverse outcomes. METHODS Cases of non-recurrent CDI were prospectively included after positive stool tests for toxins A and/or B by enzyme immunoassay (EIA) or tcdB by polymerase chain reaction. Outcomes included severe CDI (intensive care unit admission, colectomy, or death attributable to CDI within 30 days of diagnosis) and 30-day all-cause mortality. Adjusted models were developed to test hypotheses and predict outcomes. RESULTS In total, 1144 cases were included. The toxin EIA was positive in 37.2% and 35.6% of patients were of age >65 years. One of the 137 unique ribotypes was ribotype 027 (16.2%). Detectable stool toxin did not associate with outcomes. Adjusting for covariates, including age, Ribotype 027 was a significant predictor of severe CDI (90 cases; odds ratio [OR], 1.73; 95% confidence interval [CI], 1.03-2.89; P = .037) and mortality (89 cases; OR, 2.02; 95% CI, 1.19-3.43; P = .009). Concurrent antibiotic use associated with both outcomes. Both multivariable predictive models had excellent performance (area under the curve >0.8). CONCLUSIONS Detection of stool toxin A and/or B by EIA does not predict severe CDI or mortality. Infection with ribotype 027 independently predicts severe CDI and mortality. Use of concurrent antibiotics is a potentially modifiable risk factor for severe CDI.

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

Background: This study evaluated the performance of the BD ProbeTec Chlamydia trachomatis Qx (CTQ) Amplified DNA Assay on the BD Viper System with XTR Technology in a multicenter study. Methods: 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. Results: 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. Conclusions: 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.

Multicenter Evaluation of the BD Max GBS Assay for Detection of Group B Streptococci in Prenatal Vaginal and Rectal Screening Swab Specimens from Pregnant Women

ABSTRACT A new integrated extraction and real-time PCR-based system for the detection of group B streptococci in antepartum screening samples enriched in Lim broth was compared to the CDC-recommended culture method. The BD Max GBS assay exhibited acceptable sensitivity (95%) and specificity (96.7%) compared to those of the culture method in this multisite evaluation.

The Effects of a Single Cervical Inoculation of Chlamydia trachomatis on the Female Reproductive Tract of the Baboon (Papio anubis)

BACKGROUND The baboon (Papio hamadryas anubis) can be transcervically instrumented, facilitating studies of intrauterine contraception and reproductive tract infection. We sought to determine if the baboon could become infected with a single cervical inoculation of Chlamydia trachomatis. METHODS Ten female baboons were randomized and inoculated cervically with C. trachomatis serovar E (or buffer alone). Animals underwent weekly clinical and laparoscopic evaluations for four weeks and at post-inoculation week 8, to monitor upper tract infection. Cervical culture and nucleic acid amplification testing (NAAT) were completed weekly throughout the study. Animals were euthanized at week 16 and the reproductive tracts were examined histologically. RESULTS All inoculated animals developed cervical infection. The average duration of positive NAAT results was 6.8 weeks (range 2-16). Two of eight (25%) animals tested positive from fallopian tube samples. Infected animals showed histological findings consistent with chlamydial infection, such as germinal centers. Five of ten animals seroconverted to C. trachomatis. CONCLUSIONS Baboons cervically inoculated once with C. trachomatis develop infection similar to humans, with a low incidence of upper tract infection. This novel model of Chlamydia infection closely resembles human disease and opens new avenues for studying the pathogenesis of sexually transmitted infections and contraceptive safety.

Clinical evaluation of the BD ProbeTec™ Neisseria gonorrhoeae Qx amplified DNA assay on the BD Viper™ system with XTR™ technology.

Background: The excellent sensitivity and specificity of commercially available nucleic acid amplification tests (NAATs) for the identification of Neisseria gonorrhoeae have been demonstrated. This study evaluated the performance of the BD ProbeTec™ N. gonorrhoeae Qx (GCQ) Amplified DNA Assay on the BD Viper™ System with XTR™ Technology in a multicenter study. Methods: Specimens were collected at 7 geographically diverse clinical sites from 1846 women and men attending sexually transmitted disease, family planning, and obstetrics and gynecology clinics. There were 1768 evaluable participants, 994 women and 774 men. GCQ 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 GCQ assay were compared with patient infected status (PIS). For each participant, PIS was determined based on the combined results from the reference assays Aptima Combo 2® (AC2) and BD ProbeTec™ ET GC Amplified DNA Assay (PT). Results: The sensitivity versus PIS for endocervical, vaginal, and female UPT urine, and female neat urine samples was 98.5%, 100.0%, 98.5%, and 96.9%, respectively; the specificity was 99.7%, 99.1%, 99.7%, and 99.5%, respectively. The sensitivity versus PIS for male urethral swabs and both male UPT and neat urine was 100.0%, with specificities of 99.1% for the urethral swab and UPT urine and 98.9% for the neat urine. The overall GCQ assay performance was not statistically different from that of AC2 or PT. Conclusions: The GCQ assay demonstrated performance characteristics comparable with other commercially available nucleic acid–based tests such as AC2 and PT. Vaginal swabs, endocervical swabs, urethral swabs, and urine specimens may all be used for gonorrhea screening.

Diagnosis of Clostridium difficile infection: Comparison of four methods on specimens collected in Cary-Blair transport medium and tcdB PCR on fresh versus frozen samples

Clostridium difficile infection (CDI) caused by toxigenic strains of C. difficile is primarily a nosocomial infection with increasing prevalence. Stool specimens are typically collected in Cary-Blair transport medium to maximize culture-based detection of common stool pathogens. The goal of this study was to establish an analytically accurate and efficient algorithm for the detection of CDI in our patient population using samples collected in Cary-Blair transport medium. In addition, we wished to determine whether the sensitivity and specificity of PCR was affected by freezing samples before testing. Using 357 specimens, we compared four methods: enzyme immunoassay for the antigen glutamate dehydrogenase (Wampole™ C. DIFF CHEK-60 Assay, GDH), toxin A and B enzyme immunoassay (Remel ProSpecT™ C. difficile Toxin A/B Microplate Assay, Toxin EIA), cell culture cytotoxicity neutralization assay (Bartels™ Cytotoxicity Assay, CT), and real-time PCR targeting the toxin B gene (BD GeneOhm™ Cdiff Assay, PCR). The analytic sensitivity and specificity of each as determined using a combined gold standard were as follows: GDH, 100% and 93.2%; Toxin EIA, 82.9% and 82.9%; CT, 100% and 100%; PCR (performed on frozen specimens) 74.3% and 96.6%; respectively. However, the sensitivity and specificity of PCR improved to 100% when performed on 50 fresh stool samples collected in Cary-Blair. While CT remains a sensitive method for the detection of CDI, GDH offers an excellent initial screening method to rule out CDI. While the performance of each assay did not appear to be affected by collection in Cary-Blair medium, PCR performed better using fresh specimens.

Comparison of a rapid latex agglutination assay and a fluorescent-antibody technique for the detection of herpes simplex antibody

A total of 202 serum specimens was tested for the presence of herpes simplex virus antibody using a premarket latex agglutination kit (Wampole) and an indirect fluorescent antibody (IFA) technique (electronucleonics). Discrepant results between the two assays were resolved using an Enzyme-linked immunosorbent assay (ELISA) procedure. The overall sensitivity of the latex was 99.2% with a specificity of 98.5%. The latex agglutination test evaluated is a viable alternative to indirect immunofluorescence for the detection of herpes simplex virus antibody in serum samples.

Antimicrobial Susceptibilities of Group B Streptococcus Isolates from Prenatal Screening Samples

Previous published reports have shown that group B Streptococcus (GBS) isolates were 100% susceptible to both penicillin ([1][1], [2][2]) and vancomycin ([1][1]); however, reduced susceptibilities to penicillin have been documented ([3][3][–][4][8][5]). GBS susceptibilities to clindamycin and

Impact of the Levonorgestrel-Releasing Intrauterine System on the Progression of Chlamydia trachomatis Infection to Pelvic Inflammatory Disease in a Baboon Model

Background Understanding the relationship between the levonorgestrel (LNG)-releasing intrauterine system (IUS) and sexually transmitted infections (STIs) is increasingly important as use of the LNG-IUS grows to include women at higher risk for STIs. This study assessed the impact of the LNG-IUS on development of Chlamydia trachomatis pelvic inflammatory disease, using a baboon model. Methods Baboons with and those without the LNG-IUS were cervically inoculated with C. trachomatis and monitored daily, and cervical and fallopian tube swab specimens were collected weekly for C. trachomatis quantitation by nucleic acid amplification testing and culture. Vaginal swab specimens were collected for cytokine analysis, and serum samples were obtained for detection of C. trachomatis antibodies. Results The LNG-IUS resulted in an increased C. trachomatis burden in the cervix, with the bacterial burden in the LNG-IUS group diverging from that in the non-LNG-IUS group by 6 weeks after infection. One of 7 baboons in the non-LNG-IUS group and 2 of 6 in the LNG-IUS group developed pelvic inflammatory disease, while 3 animals in each group met criteria suggestive of pelvic inflammatory disease. LNG-IUS increased baseline interleukin 8 levels but failed to further upregulate interleukin 8 during infection. In LNG-IUS recipients, early perturbations in the interleukin 1β axis corresponded to decreased C. trachomatis clearance and increased T-helper type 2 immune responses. Conclusion LNG-IUS use results in delayed clearance of C. trachomatis and might alter the reproductive tract immune environment.