Search

The American Sexually Transmitted Diseases Association has, for several years, been conducting a cross-sector workshop to bring together a variety of stakeholders to develop ideas for collaboratively improving the sexually transmitted infection control efforts in the United States. In this summary, we share the content of discussions and ideas of the fourth annual workshop for future research and potential changes to practice with a focus on diagnostic capacity.

Our laboratory system tests sera for herpes simplex virus type 2 (HSV-2) IgG using the DiaSorin Liaison chemiluminescent immunoassay (CIA), with the option to confirm positive samples by a laboratory-developed HerpeSelect inhibition assay. As part of the confirmation process, the HerpeSelect HSV-2 IgG enzyme immunoassay (EIA) is performed. This study investigated the relationship between DiaSorin HSV-2 IgG CIA-positive indices and HerpeSelect HSV-2 IgG EIA results.HerpeSelect HSV-2 IgG EIA results were compiled for a cohort of consecutive DiaSorin HSV-2 IgG CIA-positive (index ≥1.10) samples. To further characterize DiaSorin CIA-positive samples that were positive (concordant) or negative (discordant) by the HerpeSelect EIA, a separate composite reference study panel was constructed and also tested using the Biokit HSV-2 IgG assay and an HSV-2 IgG inhibition assay developed for the DiaSorin instrument. Samples were classified as DiaSorin HSV-2 IgG true positive or false positive based on a composite reference using HerpeSelect EIA, Biokit, and DiaSorin inhibition results.Of 2305 consecutive DiaSorin HSV-2 IgG CIA-positive samples, 411 (17.8%) were HerpeSelect HSV-2 IgG EIA negative; 343 of 411 (83%) had DiaSorin indices of 1.10 to 3.00. For the composite reference study panel (N = 120), 59 of 60 discordant samples were classified as DiaSorin HSV-2 IgG false positive based on the composite reference, whereas 58 of 60 concordant samples were classified as true positive.Nearly all DiaSorin HSV-2 IgG CIA-positive but HerpeSelect HSV-2 IgG EIA-negative sera are falsely positive in the DiaSorin CIA. Furthermore, most DiaSorin false-positive samples exhibit low-positive indices, suggesting that guidelines for confirmatory testing should include low-positive samples by CIA and EIA.

BackgroundGenomic surveillance efforts for SARS-CoV-2 are needed to understand the epidemiology of the COVID-19 pandemic. Viral variants may impact routine diagnostic testing, increase viral transmissibility, cause differences in disease severity, have decreased susceptibility to therapeutics, and/or confer the ability to evade host immunity. While viral whole-genome sequencing (WGS) has played a leading role in surveillance programs, many laboratories lack the expertise and resources for performing WGS. This study describes the performance of multiplexed real-time reverse transcription-PCR (RT-PCR) assays for identification of SARS-CoV-2 variants.MethodsSARS-CoV-2 specimens were tested for spike-gene variants using a combination of allele-specific primer and allele-specific detection technology (PlexPrime® and PlexZyme®). Targeted detection of spike gene mutations by RT-PCR was compared to variant detection in positive specimens by WGS, including the recently emerged SARS-CoV-2 Omicron variant.ResultsA total of 398 SAR-CoV-2 RT-PCR positive and 39 negative specimens previously tested by WGS were re-tested by RT-PCR genotyping. PCR detection of spike gene mutations N501Y, E484K, and S982A correlated 100% with WGS for the 29 lineages represented, including Alpha (B.1.1.7), Beta (B.1.351), and Gamma (P.1). Incorporating the P681R spike gene mutation also allowed screening for the SARS-CoV-2 Delta variant (B.1.617.2 and AY sublineages). Further sampling of 664 specimens that were screened by WGS between June and August 2021 and then re-tested by RT-PCR showed strong agreement for Delta variant positivity: 34.5% for WGS vs 32.9% for RT-PCR in June; 100% vs 97.8% in August. In a blinded panel of 16 Omicron and 16 Delta specimens, results of RT-PCR were 100% concordant with WGS results.ConclusionsThese data demonstrate that multiplexed real-time RT-PCR genotyping has strong agreement with WGS and may provide additional SARS-CoV-2 variant screening capabilities when WGS is unavailable or cost-prohibitive. RT-PCR genotyping assays may also supplement existing sequencing efforts while providing rapid results at or near the time of diagnosis to help guide patient management.

Trichomonas vaginalis is a prevalent sexually transmitted infection (STI). Diagnosis has historically relied on either microscopic analysis or culture, the latter being the previous gold standard. However, these tests are not readily available for male diagnosis, generally only perform well for symptomatic women, and are not as sensitive as nucleic acid amplification tests (NAATs). Men are largely asymptomatic but carry the organism and transmit to their sexual partners. This multicenter, prospective study evaluated the performance of the cobas T. vaginalis/Mycoplasma genitalium (TV/MG) assay for detection of T. vaginalis DNA compared with patient infection status (PIS) defined by a combination of commercially available NAATs and culture using urogenital specimens. A total of 2,064 subjects (984 men and 1,080 women, 940 [45.5%] symptomatic, 1,124 [54.5%] asymptomatic) were evaluable. In women, sensitivity ranged from 99.4% (95% confidence interval [CI] 96.8 to 99.9%) using vaginal samples to 94.7% (95% CI 90.2 to 97.2%) in PreservCyt samples. Specificity ranged from 98.9 to 96.8% (95% CI 95.4 to 97.8%). In men, the cobas TV/MG assay was 100% sensitive for the detection of T. vaginalis in both male urine samples and meatal swabs, with specificity of 98.4% in urine samples and 92.5% in meatal swabs. The cobas TV/MG is a suitable diagnostic test for the detection of T. vaginalis, which could support public health efforts toward infection control and complement existing STI programs.

Clinical microbiology is a dynamic field that offers many licensed professionals rewarding careers that have a direct impact on patient care. Alternative careers include numerous opportunities for bachelors, masters, and doctoral level scientists in the biotechnology industry, which also impacts human health. Understanding if you are interested in an industry position or where you can apply your skill set outside the routine laboratory is important for deciding a future career path. This article explores the diagnostic life cycle of a commercial product and its stakeholders, as well as providing insight into some of the roles a career in industry can offer those looking to take their clinical microbiology experience outside the clinical laboratory.

Technology continues to have a major impact on the way that laboratory medicine is practiced. Automation, culture-independent pathogen detection methods, and rapid antimicrobial susceptibility testing are all influencing practice in the clinical microbiology laboratory and treatment of patients in the clinical practice arena. The mining of big data and its ability to guide clinical decisions through artificial intelligence and machine learning will continue to alter the value assigned to laboratory medicine. This editorial explores these changes and the challenges they pose to investigate the skill set that will be required from this and the next generation of laboratory leaders to successfully leverage the role of the clinical microbiology laboratory in a post-technology world.

Some sera tested for 1-3-beta-D-glucan to identify invasive fungal infections exhibit interference. To assess interference transience, we evaluated results for 426 patients with an interference sample followed by a later sample. Interference was transient for 73% of patients (later sample negative or positive); median time between samples was 8 days.

Serologic methods are an important part of a clinical laboratory’s portfolio of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tests and are essential to the broader response to coronavirus infectious disease 2019 (COVID-19), including epidemiological studies and vaccine development. There are currently a number of commercial SARS-CoV-2 antibody tests with emergency use authorization (EUA) from the U.S. Food and Drug Administration. In this issue of the Journal of Clinical Microbiology, H., Serologic methods are an important part of a clinical laboratory’s portfolio of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tests and are essential to the broader response to coronavirus infectious disease 2019 (COVID-19), including epidemiological studies and vaccine development. There are currently a number of commercial SARS-CoV-2 antibody tests with emergency use authorization (EUA) from the U.S. Food and Drug Administration. In this issue of the Journal of Clinical Microbiology, H. E. Prince, T. S. Givens, M. Lapé-Nixon, N. J. Clarke, et al. (J Clin Microbiol 58:e01742-20, https://doi.org/10.1128/JCM.01742-20, 2020) report the results of their evaluation of the agreement of 4 high-throughput EUA tests for SARS-CoV-2 IgG: Abbott Architect, DiaSorin Liaison, Euroimmun, and Ortho Vitros. They showed excellent agreement between the tests and rare false-positive reactivity for all tests.

Centers for Disease Control guidelines recommend hepatitis C virus (HCV) RNA testing of all HCV IgG-reactive samples, although earlier studies found that IgG-reactive samples with low indices were negative in qualitative RNA assays. To determine if previous study results could be confirmed using current real-time RT-PCR technology, we investigated the relationship between HCV IgG index (Ortho VITROS) and quantitative HCV RNA results (cobas HCV) for 2368 consecutive IgG-reactive sera. Results were segregated into Low (1.00–16.0), Medium (16.1–30.0), and High (>30.0) IgG index groups. Although median viral load (VL) of RNA-positive samples was similar in all 3 groups, the percentage with low VL (1.18–4.16 log IU/mL) was increased for the Low group. Further analysis of the Low group revealed that 23 of 370 (6%) samples with IgG indices ≤8.00 were RNA-positive, and 13/23 (57%) had low VL. Our analysis supports the Centers for Disease Control recommendation to test all HCV IgG-reactive sera for HCV RNA.

The global coronavirus (CoV) disease 2019 (COVID-19) pandemic has resulted in a worldwide shortage of viral transport media and raised questions about specimen stability. The objective of this study was to determine the stability of severe acute respiratory syndrome CoV 2 (SARS-CoV-2) RNA in specimen transport media under various storage conditions. Transport media tested included UTM, UTM-RT, ESwab, M4, and saline (0.9% NaCl). Specimen types tested included nasopharyngeal/oropharyngeal swabs in the above-named transport media, bronchoalveolar lavage (BAL) fluid, and sputum., The global coronavirus (CoV) disease 2019 (COVID-19) pandemic has resulted in a worldwide shortage of viral transport media and raised questions about specimen stability. The objective of this study was to determine the stability of severe acute respiratory syndrome CoV 2 (SARS-CoV-2) RNA in specimen transport media under various storage conditions. Transport media tested included UTM, UTM-RT, ESwab, M4, and saline (0.9% NaCl). Specimen types tested included nasopharyngeal/oropharyngeal swabs in the above-named transport media, bronchoalveolar lavage (BAL) fluid, and sputum. A high-titer SARS-CoV-2 remnant patient specimen was spiked into pooled SARS-CoV-2 RNA-negative specimen remnants for the various medium types. Aliquots of samples were stored at 18°C to 26°C, 2°C to 8°C, and −10°C to −30°C and then tested at time points up to 14 days. Specimens consistently yielded amplifiable RNA with mean cycle threshold differences of

Mycoplasma genitalium (MG) infections are a growing concern within the field of sexually transmitted infections. However, diagnostic assays for M. genitalium have been limited in the United States. As most infections are asymptomatic, individuals can unknowingly pass the infection on, and the prevalence is likely to be underestimated. Diagnosis of M. genitalium infection is recommended using a nucleic acid test. This multicenter study assessed the performance of the cobas Trichomonas vaginalis (TV)/MG assay (cobas) for the detection of M. genitalium, using 22,150 urogenital specimens from both symptomatic and asymptomatic men and women collected at geographically diverse sites across the United States., Mycoplasma genitalium (MG) infections are a growing concern within the field of sexually transmitted infections. However, diagnostic assays for M. genitalium have been limited in the United States. As most infections are asymptomatic, individuals can unknowingly pass the infection on, and the prevalence is likely to be underestimated. Diagnosis of M. genitalium infection is recommended using a nucleic acid test. This multicenter study assessed the performance of the cobas Trichomonas vaginalis (TV)/MG assay (cobas) for the detection of M. genitalium, using 22,150 urogenital specimens from both symptomatic and asymptomatic men and women collected at geographically diverse sites across the United States. The performance was compared to a reference standard of three laboratory-developed tests (LDTs). The specificity of the cobas assay for M. genitalium ranged from 96.0% to 99.8% across symptomatic and asymptomatic men and women. The sensitivities in female vaginal swabs and urine samples were 96.6% (95% confidence interval [CI], 88.5 to 99.1%) and 86.4% (95% CI, 75.5 to 93.0%), respectively. The sensitivities in male urine and meatal swab samples were 100% (95% CI, 94.0 to 100%) and 85.0% (95% CI, 73.9 to 91.9%), respectively. This study demonstrated that the cobas assay was highly sensitive and specific in all relevant clinical samples for the detection of M. genitalium.

Technology for modern clinical and public health microbiology laboratories has evolved at an impressive rate over the last two decades. Contemporary diagnostics can rapidly provide powerful data that can impact patient lives and support infectious disease outbreak investigations. At the same time, dramatic changes to health care delivery are putting new pressures on a system that is now focusing on patient-centric, value-driven, convenient care. For laboratories, balancing all these demands in a cost-contained environment remains a challenge. This article explores the current and future directions of diagnostics in our dynamic health care environment.

The evidence base for the optimal laboratory diagnosis of Clostridioides (Clostridium) difficile in adults is currently unresolved due to the uncertain performance characteristics and various combinations of tests. This systematic review evaluates the diagnostic accuracy of laboratory testing algorithms that include nucleic acid amplification tests (NAATs) to detect the presence of C. difficile., SUMMARY The evidence base for the optimal laboratory diagnosis of Clostridioides (Clostridium) difficile in adults is currently unresolved due to the uncertain performance characteristics and various combinations of tests. This systematic review evaluates the diagnostic accuracy of laboratory testing algorithms that include nucleic acid amplification tests (NAATs) to detect the presence of C. difficile. The systematic review and meta-analysis included eligible studies (those that had PICO [population, intervention, comparison, outcome] elements) that assessed the diagnostic accuracy of NAAT alone or following glutamate dehydrogenase (GDH) enzyme immunoassays (EIAs) or GDH EIAs plus C. difficile toxin EIAs (toxin). The diagnostic yield of NAAT for repeat testing after an initial negative result was also assessed. Two hundred thirty-eight studies met inclusion criteria. Seventy-two of these studies had sufficient data for meta-analysis. The strength of evidence ranged from high to insufficient. The uses of NAAT only, GDH-positive EIA followed by NAAT, and GDH-positive/toxin-negative EIA followed by NAAT are all recommended as American Society for Microbiology (ASM) best practices for the detection of the C. difficile toxin gene or organism. Meta-analysis of published evidence supports the use of testing algorithms that use NAAT alone or in combination with GDH or GDH plus toxin EIA to detect the presence of C. difficile in adults. There is insufficient evidence to recommend against repeat testing of the sample using NAAT after an initial negative result due to a lack of evidence of harm (i.e., financial, length of stay, or delay of treatment) as specified by the Laboratory Medicine Best Practices (LMBP) systematic review method in making such an assessment. Findings from this systematic review provide clarity to diagnostic testing strategies and highlight gaps, such as low numbers of GDH/toxin/PCR studies, in existing evidence on diagnostic performance, which can be used to guide future clinical research studies.

The clinical performance of the Cobas CT/NG assay on the Cobas 6800/8800 systems (Cobas) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae was established in a multisite, prospective collection study using male and female urogenital specimens; supportive data from archived specimens were also included. The results obtained with the Cobas assay were compared with the patient infected status derived from a combination of U.S., The clinical performance of the Cobas CT/NG assay on the Cobas 6800/8800 systems (Cobas) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae was established in a multisite, prospective collection study using male and female urogenital specimens; supportive data from archived specimens were also included. The results obtained with the Cobas assay were compared with the patient infected status derived from a combination of U.S. Food and Drug Administration-approved nucleic acid amplification tests to determine the sensitivity and specificity of detection from each sample type. The sensitivity of Cobas for the detection of C. trachomatis in female specimens was 95.6% (95% confidence interval [CI], 92.4% to 97.4%) for urine; 98.6% (95% CI, 95.2% to 99.6%) and 99.2% (95% CI, 95.4% to 99.9%) for clinician- and self-collected vaginal swab specimens, respectively; 93.3% (95% CI, 89.6% to 95.7%) for endocervical swabs; and 92.5% (95% CI, 88.7% to 95.1%) for cervical swab samples in PreservCyt. The specificity for the detection of C. trachomatis was ≥98.8% for all female sample types. Sensitivity and specificity estimates of Cobas for the detection of C. trachomatis in male urine samples were 100% (96.8% to 100.0%) and 99.7% (95% CI, 99.2% to 99.9%), respectively. The sensitivity of Cobas for the detection of N. gonorrhoeae in female specimens was 94.8% (95% CI, 89.6% to 97.4%) for urine; 100.0% (95% CI, 87.9% to 100.0%) and 100.0% (95% CI, 87.9% to 100.0%) for clinician- and self-collected vaginal swab specimens, respectively; 97.0% (95% CI, 91.5% to 99.0%) for endocervical swabs; and 96.6% (95% CI, 90.6% to 98.8%) for cervical samples in PreservCyt; the specificity for all female sample types was >99.0%. The sensitivity and specificity of Cobas for detecting N. gonorrhoeae in male urine were 100.0% (95% CI, 95.8% to 100.0%) and 99.5% (95% CI, 98.8% to 99.8%), respectively. Fully automated assays help fill the clinical need for a sensitive, high-throughput screening tool to aid public health efforts to control C. trachomatis and N. gonorrhoeae infections.

Published studies show that >99% of sera reactive in the reverse syphilis testing algorithm (RSTA) screening assay with an index above an assay-specific threshold confirm as reactive, with either a rapid plasma reagin-reactive (RPRR) or RPR-nonreactive/Treponema pallidum particle agglutination-reactive (TPPAR) result. However, the relationship between screen indices and confirmatory patterns has not been characterized. We thus assessed confirmatory testing results for 577 sera submitted for RSTA testing and a screen-reactive result in the DiaSorin Liaison assay. The median screen index was significantly higher for RPRR samples than TPPAR samples (55.6 versus 10.4), and the proportion with indices >28.3 (median for all 577 samples) was significantly higher for RPRR versus TPPAR samples (82% versus 26%). However, RPRR titers did not significantly correlate with screen indices (R2 = 0.02). These findings demonstrate a significant relationship between RSTA screen indices and confirmatory assay results. The clinical utility of this relationship requires further study.

In today's health care environment, laboratories are increasingly being asked to justify the acquisition of new technology. Justification is often done through a formal business case analysis. One important component of the business case is being able to show outcomes and impacts on patient care. Patient outcomes are becoming a focus of investigation following implementation of new technology and a key component to building a strong business case for that technology. Given that new technology is often more expensive than an add-on test to traditional work-ups, its true value is not fully appreciated unless it is evaluated over the continuum of care. This article discusses how to prepare a business case for the administration and key strategic considerations to create a value-driven laboratory.

Background Human rhinovirus (HRV) is a common cause of respiratory illness in children. The impact of HRV infection on 1- to 90-day-old infants is unclear. We hypothesized that HRV infection would be clinically similar to respiratory syncytial virus (RSV) infection in the hospitalized infants. Methods We conducted a retrospective study of hospitalized infants, who were 1–90 days old, with HRV or RSV within the Southern California Kaiser Permanente network over a 1-year period (August 2010 to October 2011). Results We identified 245 hospitalized infants who underwent respiratory virus testing. HRV was found in 52 infants (21%) compared to 79 infants (32%) with RSV (P = 0.008). Infants with HRV infection experienced longer hospital stays compared to those with RSV (median length of stay 4 days vs. 3 days, P = 0.009) and had fewer short hospital stays ≤3 days (P = 0.029). There was a trend in infants with HRV infection to be younger (P = 0.071) and have more fevers (P = 0.052). Conclusions Recent advances in diagnostics allow for identification of a broad range of viral pathogens in infants. Compared to RSV, HRV was associated with longer hospital stays. Additional studies and improved, more specific testing, methods are needed to further define the effects of HRV infection in infants 1–90 days old.

The impact of rapid polymerase chain reaction (PCR) technology on infectious-disease testing is continuing to evolve outside the realm of a centralized laboratory. The GeneXpert Dx system is the first unit dose, near-point-of-care, molecular device commercially available. Part I of this two-part article addressed the use of the GeneXpert system for the detection of group B Streptococcus, enterovirus, and methicillin-resistant and methicillin-susceptible Staphylococcus aureus in various clinical specimens. Part II of this article will review the advantages and disadvantages of conventional culture methods and alternative molecular technologies along with the GeneXpert system, for the detection of these microorganisms in clinical specimens.

rRNA gene sequences were used for identification and target adequacy controls in a DNA probe assay to identify isolates as Staphylococcus and, more specifically, as S. aureus within 1 hour. mecA status was simultaneously determined using a specific DNA probe. The target adequacy control guarded against false-negative mecA results.

One of the most important functions of the clinical microbiology laboratory is the identification of the etiology of sepsis. For this study, aliquots from 405 positive blood cultures were tested against a unique array of DNA probes directed against rRNA subsequences of bacteria and fungi for identification. Another 280 samples that were negative after 5 days of incubation were also tested. Blood culture bottles were incubated in a BacT/Alert3D instrument. For the rRNA assay, a 0.4-ml aliquot was removed, and the cells were pelleted by centrifugation. The pellet was washed and frozen at −70°C. Analysis of the pellet involved a lysis step and then the addition of samples to the reaction wells containing the probes in a microtiter plate format. Analysis was performed by using a hybridization protection assay. Results were taken through a series of deductive steps to obtain species, or in some cases genus, identification. Batch sample preparation required approximately 15 min, and sample analysis required another 60 min. Probe results were compared to conventional biochemical identifications. The probe test was negative for the 280 samples that were negative by the BacT/Alert 3D system and for another 21 samples that were false positive (the instrument signaled, but there was no growth). Microorganisms from the remaining 384 signal-positive samples included 60 Enterobacteriaceae , 10 Pseudomonas aeruginosa , 10 other gram-negative bacteria, 40 Staphylococcus aureus , 152 coagulase-negative staphylococci, 28 streptococci, 22 enterococci, 21 other gram-positive bacteria, 8 anaerobes, and 16 yeast organisms. Seventeen cultures were polymicrobial, and one was gram positive and culture negative. Discordance between probe and conventional identification results was noted for only 12 (1.75%) samples. This novel rapid molecular approach to the identification of bacteria and yeast in blood cultures was highly sensitive (100%) and specific (96%).

A strategy comparing molecular and conventional methods for verification of the BacT/Alert nonvent blood culture bottles (Organon Teknika, Durham, N.C.) was performed with seeded isolates. The bottles were evaluated with 12 common organisms from bloodstream infections. Overall, the bottles were equivalent as determined by conventional and molecular methods.

A shortened protocol for two peptide nucleic acid fluorescence in situ hybridization (PNA FISH) assays for the detection of Gram-negative bacilli from positive blood cultures was evaluated in a multicenter trial. There was 100% concordance between the two protocols for each assay (368 of 368 and 370 of 370 results) and 99.7% (367 of 368 and 369 of 370 results) agreement with routine laboratory techniques.

This study describes methodology for the detection and quantitation of PCR amplified DNA. Specifically we report the estimation of the prevalence of E. coli in marine waters and other environmental samples from Mamala Bay, Hawaii. High performance liquid chromatography (HPLC) was used to quantitate PCR products containing between 1 and 250 ng DNA. PCR was used to amplify E. coli DNA through the use of lamB primers. A standard curve was generated that related initial cell template concentrations to amplified product DNA concentrations within a template range of 520 to 5.2×107 cells. The standard curve was used to determine initial template concentrations of the lamB gene sequence present within 11 different environmental samples. Quantified PCR analyses were most useful when samples contained only low numbers of target organisms, and when environmental samples contained few PCR inhibitory substances, as for example in marine water samples. Quantitation of amplified DNA and comparison with culture data also suggested the presence of viable but nonculturable organisms in some environmental samples. Overall these data are unique in that they indicate the successful use of HPLC to quantitate PCR amplifications with concomitant estimation of PCR template within environmental samples.

Methicillin-resistant Staphylococcus aureus (MRSA) infections constitute a worldwide pandemic ([20][1]). There is no shortage of literature that documents the burden of disease both in the United States and globally. A recent review of the literature by Harbarth et al. ([7][2]) outlines the problem

A total of 217 specimens submitted for routine smear and culture from three different sites within the western United States were used to evaluate the GeneXpert MTB/RIF assay (for research use only) (Cepheid, Sunnyvale, CA). Overall agreement compared to culture was 89% (98% for smear positives and 72% for smear negatives) for detection of Mycobacterium tuberculosis .

The clinical microbiology laboratory plays a critical role in the detection of Staphylococcus aureus with decreased susceptibility to vancomycin. Staff education and rapid laboratory response are of utmost importance. We report on our laboratory's experience and provide recommendations for the identification and confirmation of vancomycin-intermediate S. aureus .

A multicenter clinical trial assessed the performance of the Cepheid Xpert C. difficile assay on stool specimens collected from patients suspected of having Clostridium difficile infection (CDI). A total of 2,296 unformed stool specimens, collected from seven study sites, were tested by Xpert C. difficile enrichment culture followed by cell culture cytotoxicity testing of the isolates (i.e., toxigenic culture with enrichment) and the study sites' standard C. difficile test methods. The methods included enzyme immunoassay (EIA), direct cytotoxin testing, and two- and three-step algorithms using glutamate dehydrogenase (GDH) screening followed by either EIA or EIA and an in-house PCR assay. All C. difficile strains were typed by PCR-ribotyping. Compared to results for toxigenic culture with enrichment, the sensitivity, specificity, and positive and negative predictive values of the Xpert assay were 93.5, 94.0, 73.0, and 98.8%, respectively. The overall sensitivity of the EIAs compared to that of enrichment culture was 60.0%, and the sensitivity of combined GDH algorithms was 72.9%; both were significantly lower than that of Xpert C. difficile ( P < 0.001 and P = 0.03, respectively). The sensitivity of the EIA was significantly lower than that of the Xpert C. difficile assay for detection of ribotypes 002, 027, and 106 ( P < 0.0001, P < 0.0001, and P = 0.004, respectively, Fisher's exact test), and the sensitivity of GDH algorithms for ribotypes other than 027 was lower than that for Xpert C. difficile ( P < 0.001). The Xpert C. difficile assay is a simple, rapid, and accurate method for detection of toxigenic C. difficile in unformed stool specimens and is minimally affected by strain type compared to EIA and GDH-based methods.

The incidence of Clostridium difficile infection (CDI) has risen almost 3-fold in the United States over the past decade, emphasizing the need for rapid and accurate tests for CDI. The Cepheid Xpert C. difficile assay is an integrated, closed, nucleic acid amplification system that automates sample preparation and real-time PCR detection of the toxin B gene ( tcdB ). A total of 432 stool specimens from symptomatic patients were tested by a glutamate dehydrogenase (GDH) assay, a toxin A and B enzyme immunoassay (EIA), the Xpert C. difficile assay, and a cell culture cytotoxicity neutralization assay (CCCN). The results of these methods, used individually and in combination, were compared to those of toxigenic culture. Results for the Xpert C. difficile assay alone showed a sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 94.4, 96.3, 84.0, and 98.8%, while the EIA alone gave corresponding values of 58.3, 94.7, 68.9, and 91.9%, respectively. An algorithm using the GDH assay and the EIA (plus the CCCN if the EIA was negative) showed corresponding values of 83.1, 96.7, 83.1, and 96.1%. The Xpert C. difficile assay was statistically superior to the EIA ( P , P , 0.0363). Combining the GDH and Xpert C. difficile assays lowered both the sensitivity and the NPV of the Xpert assay. The GDH-EIA-CCCN procedure required, on average, 2 days to complete testing on GDH-positive results, while testing by the Xpert C. difficile assay was completed, on average, in less than 1 h. Xpert C. difficile testing yielded the highest sensitivity and NPV, in the least amount of time, of the individual- and multiple-test algorithms evaluated in this study.

Some cases of late-onset (regressive) autism may involve abnormal flora because oral vancomycin, which is poorly absorbed, may lead to significant improvement in these children. Fecal flora of children with regressive autism was compared with that of control children, and clostridial counts were higher. The number of clostridial species found in the stools of children with autism was greater than in the stools of control children. Children with autism had 9 species of Clostridium not found in controls, whereas controls yielded only 3 species not found in children with autism. In all, there were 25 different clostridial species found. In gastric and duodenal specimens, the most striking finding was total absence of non-spore-forming anaerobes and microaerophilic bacteria from control children and significant numbers of such bacteria from children with autism. These studies demonstrate significant alterations in the upper and lower intestinal flora of children with late-onset autism and may provide insights into the nature of this disorder.