ABSTRACT The objective of the present study was to evaluate the VITEK 2 antimicrobial susceptibility test (AST) for Gram-negative (GN) plazomicin performance using the VITEK 2 and VITEK 2 Compact Systems in clinical settings and to demonstrate its equivalence to the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) technique. The clinical study conducted at four external sites followed the requirements detailed in the US Food and Drug Administration (FDA) and International Standards Organization (ISO) guidance documents and included clinical, challenge, quality, and reproducibility studies. In this multisite study, a total of 979 Enterobacterales isolates were tested. The VITEK 2 card minimum inhibitory concentration (MIC) results were compared with the reference BMD MIC results. The performance following ISO criteria indicated Essential Agreement (EA) = 97.8% and showed that VITEK 2 plazomicin MIC results for Enterobacterales tend to be in exact agreement when compared with the CLSI BMD reference method, except for Escherichia coli, when MICs tend to be in exact agreement or at least one doubling dilution lower. The analysis was also performed following the FDA criteria using the breakpoints defined by the FDA: ≤2 susceptible (S), 4 intermediate (I), and ≥8 resistant (R) for Enterobacterales. The analysis showed the following performance: EA = 98.7%, category agreement (CA) = 99.4%, and major errors (ME) = 0.1%, with no very major errors (VME) present. There are three species, Klebsiella pneumoniae , Escherichia coli, and Serratia marcescens, for which the trend is ≥ 30% and therefore addressed as a note in the US label. The plazomicin test met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. IMPORTANCE The VITEK 2 AST-GN plazomicin test is a new, automated alternative to the BMD reference method for determining minimum inhibitory concentrations (MIC) of Enterobacterales, expanding the range of automatic AST testing.

Using a nasopharyngeal (NP) or anterior nasal (NS) swab from prospectively collected or retrospective specimens, we assessed the clinical performance of the BD Respiratory Viral Panel (BD RVP) for BD MAX System against FDA-cleared or authorized comparators. Across prospective and retrospective specimens, positive percent agreement (PPA) was ≥ 98.4% for SARS-CoV-2, ≥ 96.7% for influenza (flu) A, ≥ 91.7% for respiratory syncytial virus (RSV), and 100% for flu B (retrospective only) while negative percent agreement (NPA) was ≥ 97.7% across all targets, leading to the assay FDA clearance. A head-to-head comparison of NS versus NP results with BD RVP was also performed; PPA was ≥ 90% and NPA ≥ 98.2% for SARS-CoV-2, flu A and RSV. These findings confirm that the BD MAX RVP assay performs well for detection and differentiation of the three viruses in NP and NS specimens, with strong interrater agreements for NS versus NP comparisons.

Abstract Background Some shared clinical features of SARS-CoV-2, influenza (flu), and respiratory syncytial virus (RSV) infection often pose a diagnostic challenge for clinicians. In that context, the use of molecular diagnostic systems multiplex assays, using a nasopharyngeal or nasal swab, facilitates the detection of the causing virus by differentiating between the RNA of each disease. Our study evaluated the clinical accuracy of one such multiplex PCR assay, the BD Respiratory Viral Panel for BD MAX™ System (BD MAX RVP). Methods Symptomatic patients that had a nasopharyngeal and nasal specimen prospectively collected from 6 geographical locations in the US were enrolled in the study between January and April 2022 along with nasopharyngeal swabs retrospectively collected between December 2019 and January 2022. All specimen testing was performed using the BD MAX System. Hologic® Flu A/B/RSV assay on Panther Fusion™ System was the comparator for flu A, flu B, and RSV while a composite of two out of three assays authorized under FDA Emergency Use Authorization (Roche cobas® SARS-CoV-2 on cobas® 6800 System, Hologic® Aptima® SARS-CoV-2 on Panther® System, and Quidel Lyra® SARS-CoV-2 on Applied Biosystems® 7500 Fast Dx) was used as comparator for SARS-CoV-2. Positive and negative percentage agreements (PPA and NPA, respectively) were calculated to determine performance. Reproducibility and precision assessments were also performed as part of the study. Results Tested specimens included 252 nasopharyngeal and 254 nasal swabs, prospectively collected, and 240 retrospectively acquired nasopharyngeal specimens. For prospectively collected SARS-CoV-2 nasopharyngeal specimens, PPA of 98.8% (95% CI 93.6, 99.8) and NPA of 98.2% (95% CI 94.9, 99.4) were observed while for flu A, PPA was 100% (95% CI 61.0, 100) and NPA 99.6% (95% CI 97.7, 99.9). PPA and NPA for prospectively collected SARS-CoV-2 anterior nasal specimens were 98.8% (95% CI 93.3, 99.8) and 98.3 (95% CI 95.1, 99.4), respectively. For flu A, PPA of 100% (95% CI 61.0, 100) and NPA of 99.6% (95% CI 97.8, 99.9) were observed. Lack of enrolled positive patients with flu B or RSV precluded the PPA calculation for those viruses. However, NPA for both flu B and RSV was 100% for the two specimen types. In retrospectively obtained nasopharyngeal specimens, PPA was 100% (95% CI 93.7, 100) for flu A, 100% (95% CI 93.8, 100) for flu B, and 98.4% (95% CI 91.5, 99.7) for RSV while NPA was 98.9% (95% CI 96.1, 99.7) for flu A, 98.9% (95% CI 96.1, 99.7) for flu B, and 100% (95% CI 97.9, 100) for RSV. Conclusion The BD MAX RVP assay showed a strong clinical performance in detecting and differentiating between the RNA of SARS-CoV-2, flu A and B, and RSV.

We present the first performance evaluation results for omadacycline on the VITEK 2 and VITEK 2 Compact Systems (bioMérieux, Inc.). The trial was conducted at four external sites and one internal site.

BACKGROUND:Diagnostic options to combat the increasing rates of sexually transmitted infections recorded throughout the world increasingly include multiplex assays. Here we describe the estimated sensitivity and specificity of a triplex molecular assay that simultaneously detects Chlamydia trachomatis (CT), Neisseria gonorrhoeae (or gonococci [GC]), and Trichomonas vaginalis (TV).METHODS:Participants (2547 women and 1159 men) were recruited from 12 clinics in the United States. BD CTGCTV2 for BD MAX System assay (CTGCTV2) results were obtained from vaginal and endocervical swabs, endocervical samples in cytology medium, and female and male urine. Results were compared with infection standards that were sample type and pathogen dependent.RESULTS:Female specimen sensitivity estimates ranged from 92.7% to 98.4%, 92.9% to 100%, and 86.6% to 100% for CT, GC and TV, respectively. Male urine sensitivity estimates were 96.7%, 99.2%, and 97.9% for CT, GC, and TV, respectively. Specificity estimates were >98.7% for all sample types.CONCLUSIONS:BD CTGCTV2 performed well using a variety of sample types. As a true triplex assay, performed using a benchtop instrument, BD CTGCTV2 may be useful in settings where no testing is currently performed and in settings, such as reference laboratories, where testing turnaround time may be several days. Use of this assay at local laboratories may result in greater access to testing and a shorter time to result, which are important steps for improving our ability to combat sexually transmitted infections.

Background: Postoperative shoulder infection is a significant complication requiring timely identification and treatment. Indolent infections such as those involving Cutibacterium acnes (formerly Propionibacterium acnes) provide a diagnostic dilemma as they present differently, without the acute symptoms associated with most postoperative bone and joint infections. Furthermore, C acnes is thought to be a common contaminant isolated from intraoperative cultures. With no consensus algorithm, long-held cultures play a major role in guiding management decisions in potential postoperative shoulder infection. Our study sought to determine the incidence of positive culture results in both open and arthroscopic procedures in noninfected patients, as well as to clarify whether an increase in the incubation time frame leads to an increased rate of culture growth. Methods: One hundred patients were prospectively enrolled into either the open or arthroscopic procedure group. Patients with abnormal inflammatory laboratory findings, a history of shoulder surgery, or corticosteroid injection within 6 months of surgery were excluded from the study. Three cultures were obtained for each patient: superficial tissue culture, tissue culture, and "sterile"control swab. Cultures were held for 28 days and checked at regular intervals. All patients were followed up clinically for 6 months to ensure no signs of postoperative infection occurred. Results: Ultimately, 95 patients were included in the final analysis. The false-positive rate was 17.0% in those who underwent open shoulder surgery and 10.4% in those who underwent arthroscopic shoulder surgery. The incidence of positive C acnes culture results was 6.4% in the open group, whereas C acnes was not isolated in the arthroscopic group. All positive bacterial culture results were reported within 7 days of collection. One culture result was positive for mold at 26 days. Conclusion: A relatively high false-positive culture rate occurred in both open and arthroscopic shoulder surgery. C acnes was the most commonly identified bacterium in cultures in the open surgery group. Knowledge of one's institutional false-positive culture rate could be important in avoiding potentially inappropriate treatment. Additionally, we found that holding cultures longer than 14 days did not lead to an increased rate of false-positive culture results. (C) 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

In this multisite study, Vitek 2 AST-Gram-Negative Ceftazidime/Avibactam test results for 1,073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa ) were compared to the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (sensitive [S], ≤8/4 μg/ml; resistant [R], ≥16/4 μg/ml).

High-sensitivity cardiac troponin (hs-cTn) assays facilitate early decision making in acute myocardial infarction (AMI).1 The accuracy of these assays now allow sex-specific differences in levels to be detected within healthy populations. It is thought that differences in plasma levels of cardiac troponin (cTn) are due to sex-specific variations in body composition and cardiac physiology2 and that estrogen may also play a part.3 However, the clinical relevance of this remains unclear.4 Women presenting with suspected acute coronary syndrome (ACS) are less frequently diagnosed, have poorer outcomes,5 and are more likely to have atypical symptoms than men.6 The requirement for sex-specific cutoffs may vary depending on the troponin assay, intended use, AMI type, and clinical performance estimate being assessed. Previously proposed sex-specific hs-cTnT assay cutoffs (females, 14 ng/L; males, 22 ng/L) did not alter sensitivity for AMI versus the overall cutoff (19 ng/L), but resulted in slightly lower specificity for AMI in females and higher specificity in males.4 However, it is uncertain whether sex-specific cutoffs improve hs-cTnT assay diagnostic performance. We investigated the impact of sex-specific cutoffs on performance of the Elecsys® Troponin T Gen 5 (Roche Diagnostics GmbH, Mannheim, Germany) hs-cTnT assay for diagnosing AMI and predicting 30-day major adverse cardiac events (MACE). Exploratory analyses were performed using data from two patient cohorts enrolled in prospective U.S. studies:4, 7 an ACS cohort of 1,679 patients (median age = 55 years; 48.4% females), enrolled at 15 U.S. EDs from 2011 to 2015,4 and a reference range study7 of 1,301 healthy volunteers. For our analyses, inclusion criteria included age ≥ 21 years, emergency department presentation with ACS symptoms, and provision of a baseline blood sample within 24 hours of symptom onset. Exclusion criteria included AMI in the healthy cohort, transfer from another medical facility, surgery or hospitalization within prior 3 months, cardioversion or defibrillation within prior 3 months, cardiogenic shock, and self-declared pregnancy in the ACS cohort. Following application of these criteria, our ACS cohort analyses included 1,600 patients with an initial hs-cTnT result and 1,415 with a 3-hour hs-cTnT result. All patients were adjudicated by a clinical events committee using all available clinical information according to the third universal definition of AMI.8 To assess the impact of sex-specific versus overall cutoffs on hs-cTnT assay performance, we evaluated the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of AMI diagnosis. We also calculated rates of 30-day MACE (any post-discharge death, AMI, or urgent revascularization) in patients with a 3-hour hs-cTnT result above the overall and sex-specific cutoffs by sex and AMI diagnosis. Conditional random forest modeling was used to assess which of the following factors were associated with elevated 3-hour hs-cTnT results: AMI diagnosis, age, sex, body mass index (BMI), systolic/diastolic blood pressure, race, ethnicity, current smoker, and other cardiovascular risk factors and that may predict AMI diagnosis—initial hs-cTnT result, 3-hour hs-cTnT result, percent and absolute difference between initial and 3-hour hs-cTnT results, age, sex, BMI, current smoker, and other cardiovascular risk factors. Analyses were performed using R (version 3.4.0, R Foundation for statistical computing, Vienna, Austria) and SAS (version 9.4, SAS Institute, Cary, NC) software. Our findings suggested that using sex-specific versus overall cutoffs did not influence the sensitivity or NPV of the assay; however, specificity and PPV were decreased in females and increased in males (Figure 1). In females, sensitivity and specificity, respectively, were 91.8 and 86.9% with the 14 ng/L cutoff and 91.8 and 90.2% with the 19 ng/L cutoff. In males, sensitivity and specificity, respectively, were 95.6 and 86.3% with the 22 ng/L cutoff and 95.6 and 83.0% with the 19 ng/L cutoff. Two of 63 females diagnosed with AMI had an initial hs-cTnT result between the female-specific and overall cutoffs; thus, using the lower sex-specific cutoff would increase the early/baseline AMI diagnosis rate by an absolute 3.2% in females. Three of 101 males diagnosed with AMI had an initial hs-cTnT result between the overall and male-specific cutoffs; thus, using the higher sex-specific cutoff would decrease the early AMI diagnosis rate by an absolute 3.0% in males. No patient diagnosed with AMI had a 3-hour hs-cTnT result between the respective sex-specific and overall cutoffs; thus, sex-specific cutoffs would have no impact on sensitivity by that time point. Among patients not diagnosed with AMI, 21 females and 21 males had a 3-hour hs-cTnT result between the respective sex-specific and overall cutoffs, highlighting the potential impact of sex-specific cutoffs on specificity. Three of these 21 females had a 30-day adverse cardiac event (one death 19 days after enrollment and two non-MI cardiac events on days 2 and 12 after enrollment), 15 had no further cardiac events, and three were lost to follow-up. One of the 21 males had an adverse cardiac event, 19 had no further cardiac events, and one was lost to follow-up. Among patients with 3-hour hs-cTnT results above the overall and sex-specific cutoffs, rates of 30-day MACE for patients with AMI were 13% to 14% for females (all AMI diagnosis 7/49 [14%]; overall and sex-specific cutoffs 6/45 [13%]) and 7% for males (all AMI diagnosis 6/91 [7%]; overall and sex-specific cutoffs 6/87 [7%]). For patients without AMI, rates were 6% to 7% for females (overall cutoff 4/62 [6%]; sex-specific cutoff 6/83 [7%]) and 1% for males (overall cutoff 1/109 [1%]; sex-specific cutoff 1/88 [1%]). Reviewing the association between patient characteristics by random forest modeling, AMI diagnosis, age, sex, and history of congestive heart failure were determined to have the highest importance scores for 3-hour hs-cTnT result (mean scores = 0.913, 0.117, 0.055, and 0.043, respectively). Initial and 3-hour hs-cTnT results were determined to have the highest importance scores for AMI diagnosis (0.134 and 0.114, respectively), followed by the percentage difference between initial and 3-hour hs-cTnT results (0.033). Recent controversies surrounding sex-specific cTn assay cutoffs and the underdiagnosis of AMI in females9 highlight the need for more data, a broader understanding of assay users’ requirements, and well-defined acceptance criteria. Our analysis found the diagnostic performance of the hs-cTnT assay was not substantially impacted when sex-specific cutoffs were applied to serial results: sensitivity was not altered, and specificity was slightly lower in females but higher in males. We observed clinically relevant sex-specific differences in hs-cTnT results in healthy participants, suggesting a potential role in long-term prognosis. Yet, we observed no age- or sex-specific hs-cTnT differences in patients diagnosed with AMI. However, the difference in distribution of results between patients with/without an AMI was greater in females versus males. It should be noted that patient management was based on AMI diagnosis using the U.S.-specific hs-cTnT overall 19 ng/L cutoff; a lower hs-cTnT overall cutoff of 14 ng/L is used in the rest of the world. These findings suggest that sex-specific cutoffs for hs-cTnT are not required for AMI diagnosis in patients with suspected ACS. Using sex-specific cutoffs did not substantially impact hs-cTnT assay diagnostic performance; however, among the 42 patients not diagnosed with AMI who had a 3-hour hs-cTnT result between the sex-specific and overall cutoffs, 14% of females had a 30-day MACE compared with 5% of males. Although based on a small number of events, and potentially influenced by selection bias, this finding is of some concern and its clinical significance should be explored. The magnitude of our findings is less than those of the much-cited study by Shah et al.,10 on which the call for sex-specific cutoffs is principally based. In that study, 80 (16%) and 111 (22%) females were classified as having an AMI using overall and sex-specific cutoffs for hs-cTnI, respectively, compared with 55 (11%) females using a contemporary troponin I assay. In contrast, there was only a slight increase in the number of males classified as having an AMI using a hs-cTnI (overall cutoff, n = 142 [23%]; sex-specific cutoff, n = 131 [21%]) versus a contemporary cTnI assay (n = 117 [19%]) troponin I assay. These findings may be due to the greater difference between the sex-specific (female, 16 ng/L; male, 34 ng/L) and overall (26 ng/L) cutoffs for hs-cTnI, compared with hs-cTnT. Our analysis included data concurrently collected from a large U.S. reference cohort, enabling us to account for multiple confounding factors. Study limitations included the non-standardized workup used for AMI diagnosis (although reflective of real-world practice) and the low number of AMIs observed in females (n = 49 at the 3-hour draw). Our results are specific to the Elecsys Troponin T gen 5 assay, and the analysis included only U.S. participants; these findings will need to be validated across different troponin assays and countries. It is unclear what impact clinician judgment or factors such as ECG interpretation would have on AMI diagnosis rates. When using serial hs-cTnT testing at admission and 3 hours later, sex-specific cutoffs did not change the rate of AMI diagnosis at initial presentation. However, based on serial results at 3 hours, 30-day MACE rates showed sex-specific differences. Efforts to prevent underdiagnosis of AMI in females should ensure the use of good clinical judgment, serial hs-cTnT measurements, and appropriate use of the 99th-percentile upper reference limit, which is still not used in many U.S. centers. We thank the individuals who participated in this study as well as the study investigators and their staff. Medical writing support was provided by David Evans, PhD, and Thomas Burton, BMBS (Gardiner-Caldwell Communications, Macclesfield, UK) and was funded by Roche Diagnostics International Ltd, Rotkreuz, Switzerland. COBAS, COBAS E, and ELECSYS are trademarks of Roche.

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory's SOC, which included matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

Infection with Histoplasma capsulatum typically manifests as a self-limiting pulmonary disease in immunocompetent patients. Systemic symptoms such as cutaneous lesions are associated with immunodeficient states. Our patient was an immunocompetent 68-year-old male who presented with a plaque on his left infraorbital area that was concerning for malignancy. Histological examination of the lesion revealed granulomatous inflammation and small yeast forms suggestive of H. capsulatum. The lesion resolved spontaneously and recurred 1 year later. On recurrence, histological examination again revealed yeast forms consistent with H. capsulatum. Serum and urine testing for H. capsulatum antigen were negative. Next-generation sequencing detected H. capsulatum, which supported the diagnosis of a cutaneous infection. The patient was prescribed and started treatment with itraconazole for 1 year after recurrence of the lesion, and he has not reported further disease recurrence to date. This case is unique because of the presentation of a primary cutaneous recurrent H. capsulatum lesion, and it demonstrated the utility of laboratory testing in its diagnosis.

Fungal peritonitis in the peritoneal dialysis population is difficult to diagnose promptly due to the inherently slow cultivation-based methods currently required for identification of peritonitis pathogens. Because of the moderate risk for severe complications, the need for rapid diagnostics is considerable. One possible solution to this unmet need is the T2Candida Panel, a new technology designed to detect the most common pathogenic Candida spp. directly from whole blood specimens in as little as a few hours. We hypothesized that this technology could be applied to the detection of Candida in peritoneal dialysate, a matrix not currently approved by the Food and Drug Administration for testing by this system. Remnant dialysate samples from three healthy (noninfected) pediatric peritoneal dialysis patients were spiked with Candida glabrata, serially diluted, and tested in triplicate with unaltered dialysate specimens. The assay detected C. glabrata in 100% of spiked dialysate samples across the full spectrum of dilutions tested, and no assay inhibition or cross-reactivity was noted. These findings suggest one of possibly more applications of this technology. The positive clinical implications of this test will continue to be realized as its use is validated in peritoneal dialysate and other patient specimen types.

Abstract Objectives We evaluated the performance and time to result for pathogen identification (ID) and antimicrobial susceptibility testing (AST) of the Accelerate Pheno™ system (AXDX) compared with standard of care (SOC) methods. We also assessed the hypothetical improvement in antibiotic utilization if AXDX had been implemented. Methods Clinical samples from patients with monomicrobial Gram-negative bacteraemia were tested and compared between AXDX and the SOC methods of the VERIGENE® and Bruker MALDI Biotyper® systems for ID and the VITEK® 2 system for AST. Additionally, charts were reviewed to calculate theoretical times to antibiotic de-escalation, escalation and active and optimal therapy Results ID mean time was 21 h for MALDI-TOF MS, 4.4 h for VERIGENE® and 3.7 h for AXDX. AST mean time was 35 h for VITEK® 2 and 9.0 h for AXDX. For ID, positive percentage agreement was 95.9% and negative percentage agreement was 99.9%. For AST, essential agreement was 94.5% and categorical agreement was 93.5%. If AXDX results had been available to inform patient care, 25% of patients could have been put on active therapy sooner, while 78% of patients who had therapy optimized during hospitalization could have had therapy optimized sooner. Additionally, AXDX could have reduced time to de-escalation (16 versus 31 h) and escalation (19 versus 31 h) compared with SOC. Conclusions By providing fast and reliable ID and AST results, AXDX has the potential to improve antimicrobial utilization and enhance antimicrobial stewardship.

BACKGROUND/OBJECTIVES:Antibody detection is commonly used for diagnosis of histoplasmosis, and cross-reactions have been recognised due to endemic mycoses but not cryptococcosis. We observed cross-reactions in an anti-Histoplasma antibody enzyme immunoassay (EIA) in the cerebrospinal fluid (CSF) from a patient with cryptococcal meningitis and sought to assess the risk of cross-reactive anti-Histoplasma antibodies in persons with cryptococcal meningitis. METHODS:An anti-cryptococcal antibody EIA was developed to measure CSF antibody response in HIV-infected subjects from Kampala, Uganda and previously healthy, HIV-negative subjects at the National Institutes of Health (NIH) with cryptococcal meningitis. Specimens were tested for cross-reactivity in assays for IgG anti-Histoplasma, anti-Blastomyces and anti-Coccidioides antibodies. RESULTS:Among 61 subjects with cryptococcal meningitis (44 Kampala cohort, 17 NIH cohort), elevated CSF anti-cryptococcal antibody levels existed in 38% (23/61). Of the 23 CSF specimens containing elevated anti-cryptococcal antibodies, falsely positive results were detected in antibody EIAs for histoplasmosis (8/23, 35%), coccidioidomycosis (6/23, 26%) and blastomycosis (1/23, 4%). Overall, 2% (2/81) of control CSF specimens had elevated anti-cryptococcal antibody detected, both from Indiana. CONCLUSIONS:Cryptococcal meningitis may cause false-positive results in the CSF for antibodies against Histoplasma, Blastomyces and Coccidioides. Fungal antigen testing should be performed to aid in differentiating true- and false-positive antibody results in the CSF.

OBJECTIVES:To compare the performance and time-to-result (TTR) for antimicrobial susceptibility testing (AST) of positive blood cultures (PBC) using the Accelerate Pheno™ system (AXDX) and both a direct VITEK® 2 card inoculation workflow (DV2) and traditional FDA-approved VITEK® 2 workflow using subcultured isolates (V2). METHODS:Patient samples with monomicrobial Gram-negative rod bacteremia were tested on AXDX and DV2 in tandem and compared to V2 AST results. Categorical agreement (CA) errors were adjudicated using broth microdilution. Instrumentation times and AST TTR were compared. RESULTS:AXDX and DV2 had a CA of 93.4% and 97.4%, respectively, compared to V2. Postadjudication, AXDX, DV2, and V2 had CA of 94.7%, 95.7%, and 96.5%, respectively. Instrument run times were 6.6 h, 9.4 h, and 9.2 h, and AST TTR were 8.9 h, 12.9 h and 35.5 h, respectively. CONCLUSIONS:AXDX and DV2 ASTs are fast and reliable, which may have significant antimicrobial stewardship implications.

Background. Central nervous system (CNS) histoplasmosis is a life-threatening condition and represents a diagnostic and therapeutic challenge. Isolation of Histoplasma capsulatum from cerebrospinal fluid (CSF) or brain tissue is diagnostic; however, culture is insensitive and slow growth may result in significant treatment delay. We performed a retrospective multicenter study to evaluate the sensitivity and specificity of a new anti-Histoplasma antibody enzyme immunoassay (EIA) for the detection of IgG and IgM antibody in the CSF for diagnosis of CNS histoplasmosis, the primary objective of the study. The secondary objective was to determine the effect of improvements in the Histoplasma galactomannan antigen detection EIA on the diagnosis of Histoplasma meningitis. Methods. Residual CSF specimens from patients with Histoplasma meningitis and controls were tested for Histoplasma antigen and anti-Histoplasma immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody using assays developed at MiraVista Diagnostics. Results. A total of 50 cases and 157 controls were evaluated. Fifty percent of patients with CNS histoplasmosis were immuno-compromised, 14% had other medical conditions, and 36% were healthy. Histoplasma antigen was detected in CSF in 78% of cases and the specificity was 97%. Anti-Histoplasma IgG or IgM antibody was detected in 82% of cases and the specificity was 93%. The sensitivity of detection of antibody by currently available serologic testing including immunodiffusion and complement fixation was 51% and the specificity was 96%. Testing for both CSF antigen and antibody by EIA was the most sensitive approach, detecting 98% of cases. Conclusions. Testing CSF for anti-Histoplasma IgG and IgM antibody complements antigen detection and improves the sensitivity for diagnosis of Histoplasma meningitis.

The diagnosis of central nervous system (CNS) histoplasmosis is often difficult. Although cerebrospinal fluid (CSF) (1,3)-β-d-glucan (BDG) is available as a biological marker for the diagnosis of fungal meningitis, there are limited data on its use for the diagnosis of Histoplasma meningitis. We evaluated CSF BDG detection, using the Fungitell assay, in patients with CNS histoplasmosis and controls. A total of 47 cases and 153 controls were identified. The control group included 13 patients with a CNS fungal infection other than histoplasmosis. Forty-nine percent of patients with CNS histoplasmosis and 43.8% of controls were immunocompromised. The median CSF BDG level was 85 pg/ml for cases, compared to <31 pg/ml for all controls (P < 0.05) and 82 pg/ml for controls with other causes of fungal meningitis (P = 0.27). The sensitivity for detection of BDG in CSF was 53.2%, whereas the specificity was 86.9% versus all controls and 46% versus other CNS fungal infections. CSF BDG levels of ≥80 pg/ml are neither sensitive nor specific to support a diagnosis of Histoplasma meningitis.

ABSTRACT Trichomoniasis is the most prevalent curable sexually transmitted disease (STD). It has been associated with preterm birth and the acquisition and transmission of HIV. Recently, nucleic acid amplification tests (NAAT) have been FDA cleared in the United States for detection of Trichomonas vaginalis in specimens from both women and men. This study reports the results of a multicenter study recently conducted using the Xpert TV ( T. vaginalis ) assay to test specimens from both men and women. On-demand results were available in as little as 40 min for positive specimens. A total of 1,867 women and 4,791 men were eligible for inclusion in the analysis. In women, the performance of the Xpert TV assay was compared to the patient infected status (PIS) derived from the results of InPouch TV broth culture and Aptima NAAT for T. vaginalis . The diagnostic sensitivities and specificities of the Xpert TV assay for the combined female specimens (urine samples, self-collected vaginal swabs, and endocervical swabs) ranged from 99.5 to 100% and 99.4 to 99.9%, respectively. For male urine samples, the diagnostic sensitivity and specificity were 97.2% and 99.9%, respectively, compared to PIS results derived from the results of broth culture for T. vaginalis and bidirectional gene sequencing of amplicons. Excellent performance characteristics were seen using both female and male specimens. The ease of using the Xpert TV assay should result in opportunities for enhanced screening for T. vaginalis in both men and women and, hopefully, improved control of this infection.

The incidence of neonatal Group B streptococcal (GBS) disease has significantly declined since the widespread implementation of prenatal screening of expectant mothers for urogenital and gastrointestinal tract GBS colonization. Screening methods have evolved from exclusively culture-based approaches to more rapid and highly sensitive molecular methods. We chose to evaluate the performance of 4 commercially available GBS molecular tests for detection of GBS colonization using 299 antepartum rectal–vaginal specimens submitted to our laboratory for routine GBS screening. In 97% of instances, there was agreement between all 3 systems. When testing 1, 6, and 12 samples simultaneously, all methods performed comparably, but the ARIES® GBS assay required the least total hands-on time and the illumigene® Group B Streptococcus assay required the most hands-on time.

OBJECTIVES:Health care-associated methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (SA) infections are continuing problems. Rapidly determining the MRSA colonization status of a patient facilitates practice to reduce spread of MRSA clinical disease. Sensitive detection of all SA prior to surgery, followed by decolonization, can significantly reduce postoperative infection from this pathogen. Our goal was to validate a new automated assay for this testing.METHODS:We compared performance of the cobas MRSA/SA Test on the cobas 4800 System to direct and enriched chromogenic culture using nasal swabs collected from patients at six United States sites.RESULTS:Compared to direct and enriched culture, the sensitivity for MRSA and SA was 93.1% and 93.9%, and the specificity was 97.5% and 94.2%, respectively. After discrepancy analysis, the sensitivity for MRSA and SA was 97.1% and 98.6%, and the specificity was 98.3% and 95.5%, respectively. Compared to direct culture, sensitivity for detecting any SA was 99.6%.CONCLUSIONS:The cobas MRSA/SA Test is an effective tool to simultaneously perform surveillance testing for nasal colonization of both MRSA and MSSA.

ABSTRACT Nucleic acid amplification tests (NAATs) are reliable tools for the detection of toxigenic Clostridium difficile from unformed (liquid or soft) stool samples. The objective of this study was to evaluate performance of the cobas Cdiff test on the cobas 4800 system using prospectively collected stool specimens from patients suspected of having C. difficile infection (CDI). The performance of the cobas Cdiff test was compared to the results of combined direct and broth-enriched toxigenic culture methods in a large, multicenter clinical trial. Additional discrepancy analysis was performed by using the Xpert C. difficile Epi test. Sample storage was evaluated by using contrived and fresh samples before and after storage at −20°C. Testing was performed on samples from 683 subjects (306 males and 377 females); 113 (16.5%) of 683 subjects were positive for toxigenic C. difficile by direct toxigenic culture, and 141 of 682 subjects were positive by using the combined direct and enriched toxigenic culture method (reference method), for a prevalence rate of 20.7%. The sensitivity and specificity of the cobas Cdiff test compared to the combined direct and enriched culture method were 92.9% (131/141; 95% confidence interval [CI], 87.4% to 96.1%) and 98.7% (534/541; 95% CI, 97.4% to 99.4%), respectively. Discrepancy analysis using results for retested samples from a second NAAT (Xpert C. difficile/Epi test; Cepheid, Sunnyvale, CA) found no false-negative and 4 false-positive cobas Cdiff test results. There was no difference in positive and negative results in comparisons of fresh and stored samples. These results support the use of the cobas Cdiff test as a robust aid in the diagnosis of CDI.