Risk of bias and limits of reporting in diagnostic accuracy studies for commercial point-of-care tests for respiratory pathogens.

Commercial point-of-care (POC) diagnostic tests for Group A Streptococcus, Streptococcus pneumoniae, and influenza virus have large potential diagnostic and financial impact. Many published reports on test performance, often funded by diagnostics companies, are prone to bias. The Standards for Reporting of Diagnostic Accuracy (STARD 2015) are a protocol to encourage accurate, transparent reporting. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool evaluates risk of bias and transportability of results. We used these tools to evaluate diagnostic test accuracy studies of POC studies for three respiratory pathogens. For the 96 studies analysed, compliance was <25% for 14/34 STARD 2015 standards, and 3/7 QUADAS-2 domains showed a high risk of bias. All reports lacked reporting of at least one criterion. These biases should be considered in the interpretation of study results.

Surotomycin versus vancomycin in adults with Clostridium difficile infection: primary clinical outcomes from the second pivotal, randomized, double-blind, Phase 3 trial.

BACKGROUND: The available treatment options for Clostridium difficile infection (CDI) are limited by high recurrence rates. Surotomycin was a novel bactericidal cyclic lipopeptide in development to treat CDI that demonstrated non-inferiority to vancomycin in a Phase 2 trial. OBJECTIVES: To assess surotomycin safety and clinical response (non-inferiority versus vancomycin) at the end of treatment (EOT) of CDI. Additionally, to assess surotomycin response over time and sustained response at 30-40 days post-EOT (superiority versus vancomycin). PATIENTS AND METHODS: Patients with CDI were randomized (1:1) to receive twice-daily oral surotomycin 250 mg alternating with twice-daily placebo or four-times-daily oral vancomycin 125 mg for 10 days in this Phase 3, double-blind, multicentre, international trial. Clinical response over time and sustained clinical response were monitored until the end of the trial, through a follow-up period of 30-40 days. Clinical Trial Registration: NCT01598311. RESULTS: A total of 285 and 292 patients with confirmed CDI were randomized to receive surotomycin and vancomycin, respectively. Surotomycin-associated clinical response at EOT was non-inferior to vancomycin (surotomycin/vancomycin: 83.4%/82.1%; difference 1.4%, 95% CI - 4.9, 7.6). Following treatment with surotomycin, both clinical response over time (stratified log-rank test, P = 0.277) and sustained clinical response (63.3%/59.0%; difference 4.3%, 95% CI - 3.6, 12.2) did not demonstrate superiority versus vancomycin at end of trial. Both treatments were generally well tolerated. CONCLUSIONS: Surotomycin demonstrated non-inferiority to vancomycin for CDI clinical response at EOT. Surotomycin did not demonstrate superiority to vancomycin for clinical response over time or sustained clinical response rate.

Persistence of energy-dependent localization in the Anderson-Hubbard model with increasing system size and doping.

Non-interacting systems with bounded disorder have been shown to exhibit sharp density of state peaks at the band edge which coincide with an energy range of abruptly suppressed localization. Recent work has shown that these features also occur in the presence of on-site interactions in ensembles of two-site Anderson-Hubbard systems at half filling. Here we demonstrate that this effect in interacting systems persists away from half filling, and moreover that energy regions with suppressed localization continue to appear in ensembles of larger systems despite a loss of sharp features in the density of states.

An Interface for the Direct Coupling of Small Liquid Samples to AMS.

We describe the moving wire interface attached to the 1-MV AMS system at LLNL's Center for Accelerator Mass Spectrometry for the analysis of nonvolatile liquid samples as either discrete drops or from the direct output of biochemical separatory instrumentation, such as high-performance liquid chromatography. Discrete samples containing at least a few 10s of nanograms of carbon and as little as 50 zmol 14C can be measured with a 3-5% precision in a few minutes. The dynamic range of our system spans approximately 3 orders in magnitude. Sample to sample memory is minimized by the use of fresh targets for each discrete sample or by minimizing the amount of carbon present in a peak generated by an HPLC containing a significant amount of 14C. Liquid Sample AMS provides a new technology to expand our biomedical AMS program by enabling the capability to measure low-level biochemicals in extremely small samples that would otherwise be inaccessible.

Does solid culture for tuberculosis influence clinical decision making in India?

SETTING: Medical units at an academic tertiary referral hospital in Southern India. OBJECTIVE: To investigate the impact of solid culture on Löwenstein-Jensen medium on clinical decision making. DESIGN: In a retrospective review of 150 culture-positive and 150 culture-negative consecutively sampled tuberculosis (TB) suspects, treatment decisions were analysed at presentation, after the availability of culture detection results and after the availability of drug susceptibility testing (DST) culture results. RESULTS: A total of 124 (82.7%) culture-positive patients and 35 (23.3%) culture-negative patients started anti-tuberculosis treatment prior to receiving their culture results; 101 patients (33.7%) returned for their results; two (1.3%) initiated treatment based on positive culture and no culture-negative patients discontinued treatment. DST was performed on 119 (79.3%) positive cultures: 30 (25.2%) showed any resistance, eight (6.7%) showed multidrug resistance and one (0.84%) showed extensively drug-resistant TB. Twenty-eight patients (23.5%) returned for their DST results. Based on DST, treatment was modified in four patients (3.4%). CONCLUSION: Using solid culture, 150 cultures need to be tested for one treatment modification and 30 for DST. The cost of the widespread application of culture will need to be balanced against its impact on treatment decisions in India.

Detection of human immunodeficiency virus infection in the sputum of tuberculosis patients in South India.

SETTING: A DOTS clinic in an academic tertiary referral hospital in South India. OBJECTIVE: To evaluate the performance of two rapid enzyme-linked immunoassays (EIAs) for the detection of human immunodeficiency virus (HIV) infection in sputum samples of patients with tuberculosis (TB). DESIGN: We prospectively recruited 522 consecutive out-patients presenting to the DOTS clinic with confirmed TB of any type to undergo HIV testing using reference serum EIA and index-blinded parallel sputum HIV testing with two rapid EIAs designed for oral mucosal transudate. RESULTS: HIV positivity was 14.9% (95%CI 12.1-18.4). Compared to reference serum EIA, the Oraquick™ assay was 93.1% sensitive (95%CI 83.8-97.4) and 95.3% specific (95%CI 92.7-96.9), while the Aware™ assay was 92.3% sensitive (95%CI 83.4-96.8) and 96.6% specific (95%CI 94.4-98.0). The positive predictive values were respectively 77.0% and 82.7%. After freezing of sputum, the sensitivity of both assays declined, but the specificity significantly increased. Higher sputum volume reduced the odds of obtaining a true result with both assays. CONCLUSION: HIV testing of fresh sputum is not sufficiently accurate for anonymous HIV surveillance among TB patients in a setting of low (<10%) HIV prevalence. Freezing sputum samples and limiting sputum volume for HIV testing may improve assay specificity.

Diagnostic accuracy of the microscopic observation drug susceptibility assay: a pilot study from India.

SETTING: The microscopic observation drug susceptibility (MODS) assay is a rapid, sensitive, low-cost liquid culture technique. OBJECTIVE: To establish the accuracy of MODS for the detection of active pulmonary tuberculosis (TB), and to document the costs and challenges of setting up this assay in a low-income setting. DESIGN: Prospective blinded pilot study of 200 adult TB suspects at a tertiary referral hospital in India. Reference standard included culture (Löwenstein-Jensen and automated liquid culture) and clinical diagnosis. RESULTS: Patients were mostly male (n = 122, 61.1%) and out-patients (n = 184, 92.0%), with a mean age of 40.4 years (standard deviation 16.2). Seventeen (8.5%) were human immunodeficiency virus infected and 47 (23.5%) were reference culture-positive. Compared to reference culture, MODS was 78.9% sensitive (95%CI 62.2-90.0) and 96.7% specific (95%CI 92.0-98.8). Clinical assessment suggested that MODS was false-negative in 3/8 reference culture-positive MODS-negatives and true-positive in 4/6 reference culture-negative MODS-positives. MODS was faster than solid (P < 0.001) and liquid culture (P = 0.088), and cheaper than both. CONCLUSION: MODS may be a good alternative to automated liquid culture, but there were several challenges in setting up the assay. Prior training and validation, setup costs and inability to rule out cross-contamination need to be taken into account before the test can be established.

Costs incurred by patients with pulmonary tuberculosis in rural India.

SETTING: Vellore District, Tamil Nadu, India. OBJECTIVE: To measure patient costs associated with diagnosis and the complete treatment of tuberculosis (TB). DESIGN: Prospective structured interview of 100 new smear-positive adult patients being treated for TB in Tamil Nadu, India, selected evenly from 10 representative health facilities in the state. Direct (out-of-pocket) and indirect (lost-time) costs were quantified by period of illness using a standardised questionnaire, and univariate regression investigated predictors of total cost. RESULTS: Seventy-four per cent of patients were male, with a mean age of 40.2 years. All were given a first-line regimen, and none had been previously treated. The mean direct cost was US$34.91 (SD $46.94), the mean indirect cost was $526.87 (SD $375.71), and the total mean cost per patient was $562.66 (SD $287.48). Twenty-five patients were admitted to hospital, at a mean cost of $279.43 (SD $142.88) per admission. Variation in costs was associated with admission. CONCLUSION: TB patients in India incur large costs associated with TB illness. The greatest single cost was time lost during admission. Total patient costs represent 193% of the estimated monthly income of a manual labourer.

Blinded evaluation of commercial urinary lipoarabinomannan for active tuberculosis: a pilot study.

SETTING: Urine antigen testing is an attractive strategy for the diagnosis of active tuberculosis (TB), but accuracy data are scarce. OBJECTIVE: To prospectively evaluate the diagnostic performance of commercial urinary lipoarabinomannan (LAM) antigen testing for active TB among pulmonary and extra-pulmonary TB suspects. DESIGN: Prospective blinded evaluation of 200 adult TB suspects at a tertiary referral hospital in India. Reference standards included culture and clinical diagnosis. RESULTS: Patients were 61% male (mean age 40.4 years): 8.5% were human immunodeficiency virus (HIV) infected and 47 of 200 (23.5%) were culture-positive for TB. Compared to positivity on either Löwenstein-Jensen (LJ) or BACTEC cultures, LAM sensitivity was 17.8% (95%CI 8.5-32.6), while specificity was 87.7% (95%CI 81.3-92.3). Compared to positivity on both LJ and BACTEC, LAM sensitivity was 5.8% (95%CI 12.5-44.9), with a specificity of 88.8% (95%CI 82.7-92.9). Compared to the clinical diagnosis, LAM sensitivity was 20.0% (95%CI 1.1-70.1), with a specificity of 83.3% (95%CI 50.9-97.0). HIV and smear status did not influence test accuracy. CONCLUSION: In its current form, LAM is insensitive for the diagnosis of active TB, although its specificity is adequate.

Novel tests for diagnosing tuberculous pleural effusion: what works and what does not?

Tuberculous pleuritis is a common manifestation of extrapulmonary tuberculosis and is the most common cause of pleural effusion in many countries. Conventional diagnostic tests, such as microscopic examination of the pleural fluid, biochemical tests, culture of pleural fluid, sputum or pleural tissue, and histopathological examination of pleural tissue, have known limitations. Due to these limitations, newer and more rapid diagnostic tests have been evaluated. In this review, the authors provide an overview of the performance of new diagnostic tests, including markers of specific and nonspecific immune response, nucleic acid amplification and detection, and predictive models based on combinations of markers. Directions for future development and evaluation of novel assays and biomarkers for pleural tuberculosis are also suggested.

Nucleic acid amplification tests for the diagnosis of tuberculous lymphadenitis: a systematic review.

SETTING: Lymphadenitis is the most common extra-pulmonary manifestation of tuberculosis (TB). Conventional diagnostic methods such as smear microscopy and culture are not very accurate for TB lymphadenitis. Nucleic acid amplification tests (NAAT) may offer additional diagnostic benefit. OBJECTIVE: To assess, in a systematic review, the performance of NAAT for the diagnosis of tuberculous lymphadenitis. DESIGN: We performed searches of the literature and identified 36 articles containing 49 comparisons between NAAT and a reference standard for TB lymphadenitis. Sensitivity and specificity estimates from each study were displayed in forest plots and summary receiver operating characteristic (SROC) plots. RESULTS: Overall study quality was fair, but the quality of reporting was poor in many studies. Estimates of sensitivity and specificity of NAAT were highly heterogeneous across studies, possibly due to variations in populations, study quality and test techniques. Estimates of sensitivity varied between 2% and 100%, and specificity estimates varied between 28% and 100%. Commercial NAAT assays, assays that used more than 20 mul of template and reports containing discrepant analysis provided significantly higher diagnostic accuracy. Blinding, template volume and discrepant analysis may account for some of the observed heterogeneity. CONCLUSION: Studies on NAAT for TB lymphadenitis produce highly variable and inconsistent results, precluding the determination of clinically meaningful estimates of accuracy. Study reports are not well standardised and often do not contain enough information. Because both false-positive and false-negative results are possible, NAATs will need to be applied in conjunction with conventional methods and interpreted in the context of clinical suspicion.

International standards for tuberculosis care: relevance and implications for laboratory professionals.

On World Tuberculosis (TB) Day 2006, the International Standards for Tuberculosis Care (ISTC) was officially released and widely endorsed by several agencies and organizations. The ISTC release was the culmination of a year long global effort to develop and set internationally acceptable, evidence-based standards for tuberculosis care. The ISTC describes a widely endorsed level of care that all practitioners, public and private, should seek to achieve in managing individuals who have or are suspected of having, TB and is intended to facilitate the effective engagement of all healthcare providers in delivering high quality care for patients of all ages, including those with smear-positive, smear-negative and extra-pulmonary TB, TB caused by drug-resistant Mycobacterium tuberculosis and TB/HIV coinfection. In this article, we present the ISTC, with a special focus on the diagnostic standards and describe their implications and relevance for laboratory professionals in India and worldwide. Laboratory professionals play a critical role in ensuring that all the standards are actually met by providing high quality laboratory services for smear microscopy, culture and drug susceptibility testing and other services such as testing for HIV infection. In fact, if the ISTC is widely followed, it can be expected that there will be a greater need and demand for quality assured laboratory services and this will have obvious implications for all laboratories in terms of work load, requirement for resources and trained personnel and organization of quality assurance systems.

E. coli O157 phage type 21/28 outbreak in North Cumbria associated with pasteurized milk.

In March 1999, a large community outbreak of Escherichia coli O157 infection occurred in North Cumbria. A total of 114 individuals were reported to the Outbreak Control Team (OCT); 88 had laboratory confirmed E. coli O157. Twenty-eight (32%) of the confirmed cases were admitted to hospital, including three children (3.4%) with haemolytic uraemic syndrome. There were no deaths. A case-control study found that illness was strongly associated with drinking pasteurized milk from a local farm (P = <0.0001) on single variable analysis. Microbiological investigations at the farm revealed E. coli O157 phage type (PT) 21/28 VT 2 which was indistinguishable from the human isolates by pulsed field gel electrophoresis. At the time of occurrence this was the largest E. coli O157 outbreak in England and Wales and the first E. coli O157 PT 21/28 VT 2 outbreak associated with pasteurized milk. This outbreak highlights lessons to be learnt regarding on-farm pasteurization.

Pharmacokinetics of ciprofloxacin in ICU patients on continuous veno-venous haemodiafiltration.

OBJECTIVES: To investigate the pharmacokinetics of intravenous ciprofloxacin 200 mg every 8 h in critically ill patients on continuous veno-venous haemodiafiltration (CVVHDF), one form of continuous renal replacement therapy (CRRT). DESIGN AND SETTING: Open, prospective clinical study in a multidisciplinary, intensive care unit in a university-affiliated tertiary referral hospital. PATIENTS: Six critically ill patients with acute renal failure on CVVHDF. INTERVENTIONS: Timed blood and ultrafiltrate samples were collected to allow pharmacokinetics and clearances to be calculated of initial and subsequent doses of 200 mg intravenous ciprofloxacin. CVVHD was performed with 1 l/h of dialysate and 2 l/h of predilution filtration solution, producing 3 l/h of dialysis effluent. The blood was pumped at 200 ml/min using a Gambro BMM-10 blood pump through a Hospal AN69HF haemofilter. MEASUREMENTS AND RESULTS: Ten pharmacokinetic profiles were measured. The CVVHDF displayed a urea clearance of 42 +/- 3 ml/min, and removed ciprofloxacin with a clearance of 37 +/- 7 ml/min. This rate was 2-2.5 greater than previously published for ciprofloxacin in other forms of CRRT. On average the CVVHDF was responsible for clearing a fifth of all ciprofloxacin eliminated (21 +/- 10%). The total body clearance of ciprofloxacin was 12.2 +/- 4.3 l/h. The trough concentration following the initial dose was 0.7 +/- 0.3 mg/l. The area under the plasma concentration time curves over a 24-h period ranged from 21 to 55 mg.h l-1. CONCLUSIONS: Intravenous ciprofloxacin 600 mg/day in critically ill patients using this form of CRRT produced adequate plasma levels for many resistant microbes found in intensive care units.

A fiber-optic sensor system for monitoring chlorinated hydrocarbon pollutants.

We have developed and field-tested a fiber-optic chemical sensor system for use in environmental monitoring and remediation. The system detects chlorinated hydrocarbon pollutants with colorimetry, and is based on an irreversible chemical reaction between the target compound and a specific reagent. The reaction products are detected by their absorption at 560 nm and can be monitored remotely with optical fibers. Continuous measurements are made possible by renewing the reagent from a reservoir with a miniature pumping system. The sensor has been evaluated against gas chromatography standards and has demonstrated accuracy and sensitivity (5 ppbw) sufficient for the environmental monitoring of trichloroethylene and chloroform. Successful preliminary field tests have been conducted in a variety of contamination monitoring scenarios.

Diagnosis of the Earliest Strain-Specific Interactions between Tobacco Mosaic Virus and Chloroplasts of Tobacco Leaves in Vivo by Means of Chlorophyll Fluorescence Imaging.

Fluorescence imaging was used to diagnose early stages of the strain-specific interactions between tobacco mosaic virus (strain PV230) and chloroplasts following infection of tobacco leaves (Nicotiana tabacum cv Xanthi). The earliest indication of interaction in tissues that ultimately become chlorotic was a reduction in chlorophyll fluorescence, and there was little fluorescence quenching compared with adjacent healthy tissues. Subsequently, fluorescence increased but remained unquenched. In the late stages fluorescence declined again in chlorotic regions as the chloroticmosaic symptoms developed. These in vivo data showing altered fluorescence yields confirm strain-specific interaction of virus coat protein with photosystem II (PSII) components in vitro, leading to photoinhibition and photooxidation of chlorophyll in infected cells and the development of visible chlorotic-mosaic symptoms. Although mechanisms leading to the low, unquenched fluorescence condition are not known, the intermediate high, unquenched fluorescence condition is consistent with impaired PSII electron transport as measured in vitro. Fluorescence lesions appear more rapidly and develop more extensively in high light, consistent with the faster and larger extent of symptom formation in high-light-grown leaves than in low-light-grown leaves.

Randomized angiographic trial of recombinant tissue-type plasminogen activator (alteplase) in myocardial infarction. RAAMI Study Investigators.

Clot dissolution with restoration of infarct-related artery blood flow is the likely mechanism for the improved prognosis and mortality reduction seen after thrombolytic therapy of acute myocardial infarction. A pilot study has suggested that 100 mg of recombinant tissue-type plasminogen activator (rt-PA) infused over 90 min may lead to higher patency rates than the current standard of 100 mg over 3 h. In this multicenter, randomized, open label trial, 281 patients with acute myocardial infarction receive 100 mg of rt-PA according to either the standard 3-h infusion regimen (an initial 10-mg bolus followed by 50 mg for the 1st h, then 20 mg/h for 2 h) or an accelerated 90-min regimen (15-mg bolus followed by 50 mg over 30 min, then 35 mg over 60 min). All patients also received intravenous heparin and oral aspirin during and after rt-PA infusion. At 60 min after initiation of the rt-PA infusion, the observed angiographic patency rates were 76% (95% confidence intervals 65% to 84%) in the accelerated regimen group and 63% in the control group (52% to 73%, p = 0.03). At 90 min these rates were 81% (73% to 87%) and 77% (68% to 84%), respectively (p = 0.21). Both randomized groups experienced similar rates of recurrent ischemia, reinfarction, angiographic reocclusion, other complications of myocardial infarction (including stroke and death) and bleeding complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Topography of photosynthetic activity of leaves obtained from video images of chlorophyll fluorescence.

The distribution of photosynthetic activity over the area of a leaf and its change with time was determined (at low partial pressure of O(2)) by recording images of chlorophyll fluorescence during saturating light flashes. Simultaneously, the gas exchange was being measured. Reductions of local fluorescence intensity quantitatively displayed the extent of nonphotochemical quenching; quench coefficients, q(N), were computed pixel by pixel. Because rates of photosynthetic electron transport are positively correlated with (1 - q(N)), computed images of (1 - q(N)) represented topographies of photosynthetic activity. Following application of abscisic acid to the heterobaric leaves of Xanthium strumarium L., clearly delineated regions varying in nonphotochemical quenching appeared that coincided with areoles formed by minor veins and indicated stomatal closure in groups.