Precise, wide field, and low-cost imaging and analysis of core-shell beads for digital polymerase chain reaction.

Digital droplet reactors have become a valuable tool for the analysis of single cells, organisms, or molecules by discretising reagents into picolitre or nanolitre volumes. However, DNA-based assays typically require processing of samples on the scale of tens of microlitres, with the detection of as few as one or as many as a hundred thousand fragments. Through the present work, we introduce a flow-focusing microfluidic device that produces 120 picolitre core-shell beads, which are assembled into a monolayer in a Petri dish for visualization and analysis. The bead assembly is subjected to polymerase chain reaction (PCR) amplification and fluorescence detection to digitally quantify the DNA concentration of the sample. We use a low-cost 21-megapixel digital camera and macro lens to capture wide-field fluorescence images with a 10-30 mm2 field-of-view at magnifications ranging from 5× to 2.5×. A customised Python script analysed the acquired images. Our study demonstrates the ability to perform digital PCR analysis of the entire bead assembly through end-point imaging and compare the results with those obtained through RT-qPCR.

Convective polymerase chain reaction in standard microtubes.

Polymerase chain reaction (PCR) is the most widely used method for nucleic acids amplification. To date, a huge number of versatile PCR techniques have been developed. One of the relevant goals is to shorten PCR duration, which can be achieved in several ways. Here, we report on the results regarding nucleic acids amplification by convective PCR (cPCR) in standard 0.2 ml polypropylene microtubes. The following conditions were found to be optimal for such amplification: 1) 70 µl reaction volume, 2) the supply of external temperature 145°Ð¡ for the denaturation zone and 0°Ð¡ for the annealing zone, 3) ∼30° inclination of the microtube main axis, 4) the use of nearby primers, and 5) duration of the reaction 15-20 min. At these conditions, the amplification products are accumulated in an amount sufficient to be registered by gel electrophoresis, and high sensitivity of the reaction comparable to that of conventional PCR is achieved. cPCR provided the reliable detection of SARS-CoV-2 coronavirus RNA isolated from nasopharyngeal swabs of COVID-19 patients.

Optimizing and evaluating PCR-based pooled screening during COVID-19 pandemics.

Population screening played a substantial role in safely reopening the economy and avoiding new outbreaks of COVID-19. PCR-based pooled screening makes it possible to test the population with limited resources by pooling multiple individual samples. Our study compared different population-wide screening methods as transmission-mitigating interventions, including pooled PCR, individual PCR, and antigen screening. Incorporating testing-isolation process and individual-level viral load trajectories into an epidemic model, we further studied the impacts of testing-isolation on test sensitivities. Results show that the testing-isolation process could maintain a stable test sensitivity during the outbreak by removing most infected individuals, especially during the epidemic decline. Moreover, we compared the efficiency, accuracy, and cost of different screening methods during the pandemic. Our results show that PCR-based pooled screening is cost-effective in reversing the pandemic at low prevalence. When the prevalence is high, PCR-based pooled screening may not stop the outbreak. In contrast, antigen screening with sufficient frequency could reverse the epidemic, despite the high cost and the large numbers of false positives in the screening process.

A retrospective observational study of the impact of 16s and 18s ribosomal RNA PCR on antimicrobial treatment over seven years: A tertiary hospital experience.

BACKGROUND: Although culture-based methods remain a staple element of microbiology analysis, advanced molecular methods increasingly supplement the testing repertoire. Since the advent of 16s and 18s ribosomal RNA PCR in the 2000s, there has been interest in its utility for pathogen detection. Nonetheless, studies assessing the impact on antimicrobial prescribing are limited. We report a single-centre experience of the influence of 16s and 18s PCR testing on antimicrobial treatment, including a cost-analysis. METHODS: Data were collected retrospectively for all samples sent for 16s and 18s PCR testing between January 2014 and December 2020. Results were compared to any culture-based result. Assessment focused on any change of antimicrobial treatment based on PCR result, or use of the result as supportive evidence for microbiological diagnosis. RESULTS: 310 samples relevant to 268 patients were referred for 16s/18s rRNA PCR testing during the period. Culture was performed for 234 samples. Enrichment culture was performed for 83 samples. 82 of 300 samples sent for 16s PCR had positive results (20.8%). When culture was performed, enrichment reduced the outcome of 16s PCR only positive results (4/36 [11.1%] versus 14/35 [40.0%], p = 0.030 where a pathogen found). 18s PCR yielded 9 positive results from 67 samples. The 16s PCR result influenced antimicrobial change for 6 patients (2.2%). We estimated the cost for 16s PCR testing to result in one significant change in antimicrobial therapy to be €3,340. 18s PCR did not alter antimicrobial treatment. CONCLUSION: There was limited impact of 16s PCR results on antimicrobial treatments. Relevance to practice was affected by relatively long turn-around-time for results. Utility may be increased in specialised surgical centres, or by reducing turn-around-time. Enrichment culture should be considered on samples where 16s PCR is requested. There remains limited evidence for use of 18s PCR in clinical management, and further studies in this area are likely warranted.

Temporary Regulatory Deviations and the Coronavirus Disease 2019 (COVID-19) PCR Labeling Update Study Indicate What Laboratory-Developed Test Regulation by the US Food and Drug Administration (FDA) Could Look Like.

The coronavirus disease 2019 (COVID-19) response necessitated innovations and a series of regulatory deviations that also affected laboratory-developed tests (LDTs). To examine real-world consequences and specify regulatory paradigm shifts, legislative proposals were aligned on a common timeline with Emergency Use Authorization (EUA) of LDTs and the US Food and Drug Administration (FDA)-orchestrated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) labeling update study. The initial EUA adoption by LDT developers shows that the FDA can have oversight over LDTs. We used efficiency-corrected microcosting of our EUA PCR assay to estimate the national cost of the labeling update study to $0.3 to $1.4 million US dollars. Labeling update study performance data showed lower average detection limits in commercial in vitro diagnostic (IVD) assays versus LDTs (32,000 ± 75,000 versus 71,000 ± 147,000 nucleic acid amplification tests/mL; P = 0.04); however, comparison also shows that FDA review of IVD assays and LDTs did not prevent differences between initial and labeling update performance (IVD assay, P < 0.0001; LDT, P = 0.003). The regulatory shifts re-emphasized that both commercial tests and LDTs rely heavily on laboratory competence and procedures; however, lack of performance data on authorized tests, when clinically implemented, precludes assessment of the benefit related to regulatory review. Temporary regulatory deviations during the pandemic and regulatory science tools (ie, reference material) have generated valuable real-world evidence to inform pending legislation regarding LDT regulation.

Routine testing for herpes simplex virus in bronchoalveolar lavage specimens is unwarranted.

Herpes simplex virus (HSV) infections of the lung are rare, but HSV is occasionally detected in bronchoalveolar lavage (BAL) specimens. We assessed whether routinely performing HSV PCR tests in BAL specimens is warranted. HSV was detected in 7% (52/722) of BALs. In 47% of HSV-positive patients a typical respiratory virus or pathologic microorganism was identified. Oral HSV reactivation was identified in 27%; however, anti-HSV therapy was initiated in just three patients following the positive HSV test. Patients undergoing BAL for transplant surveillance received anti-HSV prophylaxis more often than those with acute respiratory failure, but both groups did not differ significantly in terms of patient outcome or co-infections. No patient was diagnosed with HSV pneumonia. These findings suggest that positive HSV PCR results in BAL specimens most commonly represents contamination from oral HSV reactivation, and that HSV PCR should be ordered selectively, rather than routinely, as part of a test panel.

Quantification of the Tradeoff between Test Sensitivity and Test Frequency in a COVID-19 Epidemic-A Multi-Scale Modeling Approach.

Control strategies that employ real time polymerase chain reaction (RT-PCR) tests for the diagnosis and surveillance of COVID-19 epidemic are inefficient in fighting the epidemic due to high cost, delays in obtaining results, and the need of specialized personnel and equipment for laboratory processing. Cheaper and faster alternatives, such as antigen and paper-strip tests, have been proposed. They return results rapidly, but have lower sensitivity thresholds for detecting virus. To quantify the effects of the tradeoffs between sensitivity, cost, testing frequency, and delay in test return on the overall course of an outbreak, we built a multi-scale immuno-epidemiological model that connects the virus profile of infected individuals with transmission and testing at the population level. We investigated various randomized testing strategies and found that, for fixed testing capacity, lower sensitivity tests with shorter return delays slightly flatten the daily incidence curve and delay the time to the peak daily incidence. However, compared with RT-PCR testing, they do not always reduce the cumulative case count at half a year into the outbreak. When testing frequency is increased to account for the lower cost of less sensitive tests, we observe a large reduction in cumulative case counts, from 55.4% to as low as 1.22% half a year into the outbreak. The improvement is preserved even when the testing budget is reduced by one half or one third. Our results predict that surveillance testing that employs low-sensitivity tests at high frequency is an effective tool for epidemic control.

An economic reappraisal of hepatitis B virus testing strategy for blood donors in Taiwan.

BACKGROUND AND OBJECTIVES: Taiwan is among the few hepatitis B virus (HBV) high-endemic countries that implement universal mini-pool nucleic acid testing (MP-NAT) and hepatitis B surface antigen (HBsAg) testing together with confirmatory individual donor nucleic acid testing (ID-NAT) for its blood supply since 2013. The aim of this study was to reappraise the value of HBsAg test in Taiwan's HBV testing strategy. MATERIALS AND METHODS: A Markov model was constructed, and cost-effectiveness analysis was conducted in order to reappraise the existing HBV screening strategy in Taiwan. RESULTS: The incremental cost-effectiveness ratio (ICER) for the current testing strategy in Taiwan was estimated to be $US 443 154 per quality-adjusted life year (QALY) gained. This is almost six times the willingness-to-pay (WTP) threshold that reflects local preferences. CONCLUSION: Universal HBsAg and MP-8-NAT together with confirmatory ID-NAT testing prevents a significant amount of HBV infections from entering the Taiwan blood supply. However, this comes at a disproportionate increase in cost.

Detecting SARS-CoV-2 at point of care: preliminary data comparing loop-mediated isothermal amplification (LAMP) to polymerase chain reaction (PCR).

BACKGROUND: A cost effective and efficient diagnostic tool for COVID-19 as near to the point of care (PoC) as possible would be a game changer in the current pandemic. We tested reverse transcription loop mediated isothermal amplification (RT-LAMP), a method which can produce results in under 30 min, alongside standard methods in a real-life clinical setting. METHODS: This prospective service improvement project piloted an RT-LAMP method on nasal and pharyngeal swabs on 21 residents of a high dependency care home, with two index COVID-19 cases, and compared it to multiplex tandem reverse transcription polymerase chain reaction (RT-PCR). We recorded vital signs of patients to correlate clinical and laboratory information and calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of a single swab using RT-LAMP compared with the current standard, RT-PCR, as per Standards for Reporting Diagnostic Accuracy Studies (STARD) guidelines. RESULTS: The novel method accurately detected 8/10 RT-PCR positive cases and identified a further 3 positive cases. Eight further cases were negative using both methods. Using repeated RT-PCR as a "gold standard", the sensitivity and specificity of a single novel test were 80 and 73% respectively. PPV was 73% and NPV was 83%. Incorporating retesting of low signal RT-LAMP positives improved the specificity to 100%. We also speculate that hypothermia may be a significant early clinical sign of COVID-19. CONCLUSIONS: RT-LAMP testing for SARS-CoV-2 was found to be promising, fast and to work equivalently to RT-PCR methods. RT-LAMP has the potential to transform COVID-19 detection, bringing rapid and accurate testing to the PoC. RT-LAMP could be deployed in mobile community testing units, care homes and hospitals to detect disease early and prevent spread.

Diagnostic Strategies toward Clinical Implementation of Liquid Biopsy RAS/BRAF Circulating Tumor DNA Analyses in Patients with Metastatic Colorectal Cancer.

Detection of KRAS, NRAS, and BRAF mutations in tumor tissue is currently used to predict resistance to treatment with anti-epidermal growth factor receptor (EGFR) antibodies in patients with metastatic colorectal cancer (mCRC). Liquid biopsies are minimally invasive, and cell-free circulating tumor DNA (ctDNA) mutation analyses may better represent tumor heterogeneity. This study examined the incorporation of liquid biopsy RAS/BRAF ctDNA analyses into diagnostic strategies to determine mCRC patient eligibility for anti-EGFR therapy. Tumor tissue and liquid biopsies were collected from 100 mCRC patients with liver-only metastases in a multicenter prospective clinical trial. Three diagnostic strategies incorporating droplet digital PCR ctDNA analyses were compared with routine tumor tissue RAS/BRAF mutation profiling using decision tree analyses. Tissue DNA mutations in KRAS, NRAS, and BRAF were present in 54%, 0%, and 3% of mCRC patients, respectively. A 93% concordance was observed between tissue DNA and liquid biopsy ctDNA mutations. The proportion of patients with RAS/BRAF alterations increased from 57% to 60% for diagnostic strategies that combined tissue and liquid biopsy mutation analyses. Consecutive RAS/BRAF ctDNA analysis followed by tissue DNA analysis in case of a liquid biopsy-negative result appeared to be the most optimal diagnostic strategy to comprehensively determine eligibility for anti-EGFR therapy in a cost-saving manner. These results highlight the potential clinical utility of liquid biopsies for detecting primary resistance to anti-EGFR-targeted therapies.

Portable and accurate diagnostics for COVID-19: Combined use of the miniPCR thermocycler and a well-plate reader for SARS-CoV-2 virus detection.

The coronavirus disease 2019 (COVID-19) pandemic has crudely demonstrated the need for massive and rapid diagnostics. By the first week of July, more than 10,000,000 positive cases of COVID-19 have been reported worldwide, although this number could be greatly underestimated. In the case of an epidemic emergency, the first line of response should be based on commercially available and validated resources. Here, we demonstrate the use of the miniPCR, a commercial compact and portable PCR device recently available on the market, in combination with a commercial well-plate reader as a diagnostic system for detecting genetic material of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19. We used the miniPCR to detect and amplify SARS-CoV-2 DNA sequences using the sets of initiators recommended by the World Health Organization (WHO) for targeting three different regions that encode for the N protein. Prior to amplification, samples were combined with a DNA intercalating reagent (i.e., EvaGreen Dye). Sample fluorescence after amplification was then read using a commercial 96-well plate reader. This straightforward method allows the detection and amplification of SARS-CoV-2 nucleic acids in the range of ~625 to 2×105 DNA copies. The accuracy and simplicity of this diagnostics strategy may provide a cost-efficient and reliable alternative for COVID-19 pandemic testing, particularly in underdeveloped regions where RT-QPCR instrument availability may be limited. The portability, ease of use, and reproducibility of the miniPCR makes it a reliable alternative for deployment in point-of-care SARS-CoV-2 detection efforts during pandemics.

Comparison of loop-mediated isothermal amplification (LAMP) and PCR for the diagnosis of infection with Trypanosoma brucei ssp. in equids in The Gambia.

INTRODUCTION: Infection of equids with Trypanosoma brucei (T. brucei) ssp. is of socioeconomic importance across sub-Saharan Africa as the disease often progresses to cause fatal meningoencephalitis. Loop-mediated isothermal amplification (LAMP) has been developed as a cost-effective molecular diagnostic test and is potentially applicable for use in field-based laboratories. PART I: Threshold levels for T. brucei ssp. detection by LAMP were determined using whole equine blood specimens spiked with known concentrations of parasites. Results were compared to OIE antemortem gold standard of T. brucei-PCR (TBR-PCR). RESULTS I: Threshold for detection of T. brucei ssp. on extracted DNA from whole blood was 1 parasite/ml blood for LAMP and TBR-PCR, and there was excellent agreement (14/15) between tests at high (1 x 103/ml) concentrations of parasites. Detection threshold was 100 parasites/ml using LAMP on whole blood (LWB). Threshold for LWB improved to 10 parasites/ml with detergent included. Performance was excellent for LAMP at high (1 x 103/ml) concentrations of parasites (15/15, 100%) but was variable at lower concentrations. Agreement between tests was weak to moderate, with the highest for TBR-PCR and LAMP on DNA extracted from whole blood (Cohen's kappa 0.95, 95% CI 0.64-1.00). PART II: A prospective cross-sectional study of working equids meeting clinical criteria for trypanosomiasis was undertaken in The Gambia. LAMP was evaluated against subsequent TBR-PCR. RESULTS II: Whole blood samples from 321 equids in The Gambia were processed under field conditions. There was weak agreement between LWB and TBR-PCR (Cohen's kappa 0.34, 95% CI 0.19-0.49) but excellent agreement when testing CSF (100% agreement on 6 samples). CONCLUSIONS: Findings support that LAMP is comparable to PCR when used on CSF samples in the field, an important tool for clinical decision making. Results suggest repeatability is low in animals with low parasitaemia. Negative samples should be interpreted in the context of clinical presentation.

Application of commercial kits using DNA-based and immunochemical methods for determination of shrimp allergens in kimchi and its ingredients.

Shrimps cause a significant part of crustacea-related allergies. It is used in processed foods, including fermented Korean foods, such as kimchi. Even low amounts of shrimp allergens can provoke reactions in consumers allergic to shrimp. Accurate food labeling is the most effective means of preventing the consumption of allergenic ingredients. To validate labeling compliance and minimize the risk of cross-contaminations, the effectiveness of methodologies used for the detection of allergens in foods should be compared. Here, seven commercial kits, based on quantitative real-time polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay (ELISA), were assessed for their ability to detect the presence of shrimp allergens in food. Our results showed that SureFood real-time PCR kit and Ridascreen ELISA kit had the highest recovery, whereas five other kits underperformed in the determination of allergen content of kimchi and its ingredients. The variation in recovery among the kits depended on the limit of detection and reactivity to the shrimp allergens, tropomyosin, and sarcoplasmic calcium-binding protein. PRACTICAL APPLICATION: This research confirms the performance of commercial kits to detect the presence of shrimp allergens in kimchi, and demonstrates that the sensitivity of these kits depends on reactivity to the specific shrimp allergenic proteins. These results can be used to food allergy labeling and can be applied by the food industry to develop allergen test kits for fermented foods with improved performance.

A pooled analysis of the LAMP assay for the detection of Neisseria meningitidis.

BACKGROUND: Neisseria meningitidis is a major cause of bacterial meningitis, and these infections are associated with a high mortality rate. Rapid and reliable diagnosis of bacterial meningitis is critical in clinical practice. However, this disease often occurs in economically depressed areas, so an inexpensive, easy to use, and accurate technology is needed. We performed a pooled-analysis to assess the potential of the recently developed loop-mediated isothermal amplification (LAMP) assay for detection of meningococcus. METHODS: Pubmed, Embase, and Web of Science were searched to identify original studies that used the LAMP assay to detect meningococcus. After pooling of data, the sensitivity and specificity were calculated, a summary receiver operating characteristic (SROC) curve was determined, and the area under the SROC curve was computed to determine diagnostic accuracy. Publication bias was assessed using Deek's funnel plot. RESULTS: We examined 14 studies within 6 publications. The LAMP assay had high sensitivity (94%) and specificity (100%) in the detection of meningococcus in all studies. The area under the SROC curve (0.980) indicated high overall accuracy of the LAMP assay. There was no evidence of publication bias. DISCUSSION: The LAMP assay has accuracy comparable to bacterial culture and PCR for detection of meningococcus, but is less expensive and easier to use. We suggest the adoption of the LAMP assay to detect meningococcus, especially in economically depressed areas.

Knowledge at what cost? An audit of the utility of panfungal PCR performed on bronchoalveolar lavage fluid specimens at a tertiary mycology laboratory.

The diagnostic utility and costs of panfungal PCR assays for invasive fungal disease (IFD) from bronchoalveolar lavage fluid (BALF) specimens are incompletely defined. In a retrospective audit, panfungal PCR results from 2014-2018 were matched with information on request forms and the registrar/microbiologist diary of clinical liaison. Identification of a single fungus other than a commensal was considered potentially clinically significant, and assessed for clinical relevance. Of 1002 specimens tested, an estimated 90% were requested in patients without clinical suspicion of IFD. There were 530 (52.9%) PCR-positive results of which 485/530 (91.5%) identified multiple fungal species or commensal fungi; 45 (8.5%) were clinically significant but only in 12 (1.2%) was panfungal PCR the sole diagnostic test leading to IFD diagnosis, all in immunocompromised patients with clinical suspicion of IFD. Costs of panfungal PCR tests averaged AUD 133 per test, or AUD 26,767/annum. However, the average cost-per-diagnosis achieved was AUD 15,978/annum. Limiting testing to patients at risk and with clinical suspicion of IFD, may save over AUD 13,383/annum (assuming 50-90% reduction in testing). The value-added utility of panfungal PCR on BALF is 1.2% (12/1002). We have since introduced pre-analytical stewardship limiting routine panfungal PCR testing of BALF to high-risk patients in our hospital.

Optimization of a Low-Cost, Sensitive PNA Clamping PCR Method for JAK2 V617F Variant Detection.

BACKGROUND: The JAK2 V617F variant is diagnostic for myeloproliferative neoplasms, a group of clonal disorders of hematopoietic stem and progenitor cells. Although several approaches have been developed to detect the variant, a gold standard diagnostic method has not yet been defined. We describe a simple, fast, and cost-effective PCR-based approach that enhances test specificity and sensitivity by blocking the amplification of the large excess of wild-type DNA. METHODS: The method involves using an oligo peptide nucleic acid (PNA) perfectly matching its corresponding DNA sequence. The PCR protocol was optimized by collecting a detailed thermodynamic data set on PNA-DNA wild-type duplexes by circular dichroism melting experiments. The specificity and sensitivity of PNA clamping PCR were assessed by genotyping 50 patients with myeloproliferative neoplasm who carried the JAK2 V617F variant and 50 healthy donors. RESULTS: The optimized protocol enabled selective amplification of the variant alleles, achieving maximum sensitivity (100%) and specificity (100%). Analytical sensitivity was 0.05% of variant alleles as assessed by serial dilutions of DNA from the HEL cell line (which carries the JAK2 V617F variant) mixed to wild-type DNA from healthy donors. The JAK2 V617F variant test performed according to this method has better diagnostic performance than its 2 main PCR-based competitors, at much lower cost. CONCLUSIONS: High sensitivity and specificity and cost-effectiveness make PNA clamping PCR a useful testing platform for the detection of minor allele variants in small-scale diagnostic laboratories. It promises to improve patient care while enabling significant healthcare savings.

Clinical utility and cost-effectiveness of bacterial 16S rRNA and targeted PCR based diagnostic testing in a UK microbiology laboratory network.

16S ribosomal-ribonucleic acid polymerase chain reaction (PCR) and targeted PCR aid microbiological diagnosis in culture-negative clinical samples. Despite routine clinical use, there remains a paucity of data on their effectiveness across a variety of clinical sample types, and cost-effectiveness. In this 4 year multicentre retrospective observational study, all clinical samples referred for 16S PCR and/or targeted PCR from a laboratory network serving seven London hospitals were identified. Laboratory, clinical, prescribing, and economic variables were analysed. 78/607 samples were 16S PCR positive; pus samples were most frequently positive (29/84; p < 0.0001), and CSF least (8/149; p = 0.003). 210/607 samples had targeted PCR (361 targets requested across 23 organisms) with 43/361 positive; respiratory samples (13/37; p = 0.01) had the highest detection rate. Molecular diagnostics provided a supportive microbiological diagnosis for 21 patients and a new diagnosis for 58. 14/91 patients with prescribing information available and a positive PCR result had antimicrobial de-escalation. For culture-negative samples, mean cost-per-positive 16S PCR result was £568.37 and £292.84 for targeted PCR, equating to £4041.76 and £1506.03 respectively for one prescription change. 16S PCR is more expensive than targeted PCR, with both assisting in microbiological diagnosis but uncommonly enabling antimicrobial change. Rigorous referral pathways for molecular tests may result in significant fiscal savings.

The impact of changing reflexive to clinician-ordered Clostridioides difficile polymerase chain reaction (PCR) testing for indeterminate cases: Cost savings without associated adverse events.

OBJECTIVE: To evaluate changing Clostridioides difficile infection (CDI) testing among inpatients with indeterminate enzyme immunoassay (EIA) results (antigen+/toxin-) from reflexive polymerase chain reaction (PCR) testing to clinician-ordered PCR testing. DESIGN: Multicenter, before-and-after, quasi-experimental study. SETTING: Four large urban tertiary-care hospitals. METHODS: We evaluated two 6-month periods before and after an intervention. The primary study outcome was the change in the number of CDI diagnoses between periods. Secondary outcomes included the number of PCR tests performed, adverse events, and healthcare cost savings. RESULTS: In total, 500 EIA-indeterminate C. difficile test results were evaluated: 281 before the intervention and 219 thereafter. CDI was diagnosed by PCR among EIA-indeterminate cases in 182 in the preintervention period versus 94 patients in the postintervention period (48% reduction; P < .01). PCR testing was performed in 99.6% of indeterminate cases (280 of 281; 1 not performed due to an inhibitor) in the preintervention period versus 66% (144 of 219) in the postintervention period (34% reduction; P < .01). We observed no differences between study periods in 30-day all-cause (P = .96), GI-related (P = .93), or C. difficile (P = .47) readmissions, nor in 30-day C. difficile infections (P > .99). No patient without a PCR test in the postintervention period and not treated was later diagnosed with CDI. Each reflexive PCR test not performed led to a cost savings of $4,498 per patient. CONCLUSIONS: Applying diagnostic stewardship to C. difficile PCR testing in the inpatient setting led to significant reductions in both testing and cases. Changing the C. difficile PCR testing algorithm for EIA-indeterminate cases from reflexive to clinician-required ordering resulted in valuable cost savings without associated adverse events.

Cost-Effectiveness Analysis of Screening for Persistent Hepatitis E Virus Infection in Solid Organ Transplant Patients in the United Kingdom: A Model-Based Economic Evaluation.

BACKGROUND: Despite potentially severe and fatal outcomes, recent studies of solid organ transplant (SOT) recipients in Europe suggest that hepatitis E virus (HEV) infection is underdiagnosed, with a prevalence of active infection of up to 4.4%. OBJECTIVES: To determine the cost-effectiveness of introducing routine screening for HEV infection in SOT recipients in the UK. METHODS: A Markov cohort model was developed to evaluate the cost-utility of 4 HEV screening options over the lifetime of 1000 SOT recipients. The current baseline of nonsystematic testing was compared with annual screening of all patients by polymerase chain reaction (PCR; strategy A) or HEV-antigen (HEV-Ag) detection (strategy B) and selective screening of patients who have a raised alanine aminotransferase (ALT) value by PCR (strategy C) or HEV-Ag (strategy D). The primary outcome was the incremental cost per quality-adjusted life-year (QALY). We adopted the National Health Service (NHS) perspective and discounted future costs and benefits at 3.5%. RESULTS: At a willingness-to-pay of £20 000/QALY gained, systematic screening of SOT patients by any method (strategy A-D) had a high probability (77.9%) of being cost-effective. Among screening strategies, strategy D is optimal and expected to be cost-saving to the NHS; if only PCR testing strategies are considered, then strategy C becomes cost-effective (£660/QALY). These findings were robust against a wide range of sensitivity and scenario analyses. CONCLUSIONS: Our model showed that routine screening for HEV in SOT patients is very likely to be cost-effective in the UK, particularly in patients presenting with an abnormal alanine aminotransferase.

Current Clinical Methods for Detection of Peri-Prosthetic Joint Infection.

Background: Currently, one of the most pressing problems in the field of orthopedic surgery is peri-prosthetic joint infection [PJI]. While there are numerous ways to detect PJI, current clinical detection methods differ across institutions and have varying criteria and protocols. Some of these methods include the Modified Musculoskeletal Infection Society system, culturing, polymerase chain reaction, the determination of the presence of certain biomarkers, testing for the presence of alpha defensin peptides, and leukocyte level testing. Methods: This review summarizes the most recent publications in the field of PJI detection to highlight current strengths as well as provide future directions to find the system for the quickest, cost-effective, and most accurate way to diagnose these types of infections. Results: The results of this literature review suggest that, while each method of diagnosis has its advantages, each has various drawbacks as well. Current methods can be expensive, take days to weeks to complete, be prone to contamination, and can produce ambiguous results. Conclusions: The findings in this review emphasize the need for a more comprehensive and accurate system for diagnosing PJI. In addition, the specific comparison of advantages and drawbacks can be useful for researchers and clinicians with goals of creating new diagnostic tests for PJIs, as well as in clinical scenarios to determine the correct treatment for patients.