Laboratory Proficiency Testing Research Articles

A-280 The Good, the Bad, and the Downright Inappropriate reporting of Gram Positive Resistance Genes in a Proficiency Testing Program

Abstract Background Molecular technologies can rapidly identify the pathogen, allowing for the correct antimicrobial agent to be used for initial treatment. Many laboratories have implemented molecular technologies to identify the causative agents of infections from various bodily sources. Screening for potential resistance genes to common antimicrobial agents provides high value to clinicians to help guide optimal antimicrobial therapy selection. CLIA ‘88 required proficiency testing for physician office laboratories in 1994. This was in addition to the requirement for hospital and reference laboratories instituted under CLIA ‘67. This study compares the accuracy of laboratory performance for molecular multiplex platforms in the detection of Gram positive resistance genes from gold standard qualified samples in a novel proficiency program. Methods American Proficiency Institute, an independent proficiency testing provider, reviewed the reporting of various molecular multiplex systems against simulated patient samples in proficiency samples offered in 2023. Participants were instructed to only report resistance genes their systems were capable of testing for, and ensure they were appropriate for the organism recovered. Failure rates for participants were evaluated against an 80% participant consensus standard for detection of resistance genes. Results During the 2023 proficiency year, Gram positive targets were included 14 times in 4 different multiplex programs. Accuracy for correct reporting of resistance genes appropriate for the organism recovered ranged between 71.0%- 100%. Conversely, the number of laboratories reporting resistance genes that were inappropriate for the organism recovered ranged between 2.0% - 67.0%. Conclusions Based on the results reported by participants in API’s proficiency event, Molecular Multiplex platforms are accurately identifying Gram positive resistance genes. However, many participants using both FDA approved and LDT systems reported results for resistance genes that were not applicable for the organism recovered. This inaccurate reporting could potentially lead to inappropriate antimicrobial therapies being prescribed.

Comparison of the Machigin and CAL Methods for Extraction of Plant Available P in Soils

ABSTRACT Fertilizer recommendations for phosphorus (P) are generally based on the soil content of plant available P and the amount of P exported by the harvested crop. In countries of the former Soviet Union (SU), a widespread method is the Machigin extraction. The relationships between soil P contents extracted with this and other European methods are not well established. Here, we compare the Machigin soil P extraction method with the Calcium Ammonium Lactate P(CAL) procedure that is commonly used in Central Europe. Both methods were tested with 94 soil samples originating from Kyrgyzstan, Ukraine, and Germany. Overall, the P amount extracted with the CAL method was 2.8 times higher than that extracted with the Machigin method. However, using results from all analyzed individual soil samples, the relation between P(CAL) and P(Machigin) showed large scatter and an R2 of only 0.364. Differing relations between P(CAL) and P(Machigin) were observed for soils with pH >7 and <7. However, these are overshadowed by differences between the three geographic groups of the soil samples. The estimated soil P fertility classes for the Machigin extraction were mostly higher than for the German (CAL) procedure, resulting in lower fertilizer recommendations for the Machigin method. To improve the accuracy of conversion between both methods, evaluation of laboratory proficiency tests (i.e. analysis of the same soil samples in different laboratories with the same methods) of the Machigin method should be useful.

Production and Performance Assessment of a Severe Acute Respiratory Syndrome Coronavirus 2 Biomimetic in a Verification Program for Pandemic Readiness

During the early stages of the 2019 coronavirus disease (COVID-19) pandemic in South Africa, one of many challenges included availability of control material for laboratory proficiency testing programs. Proficiency testing control material using live severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or RNA extracted from cell culture was either biohazardous or costly, particularly in resource-limited settings. This study reports the development and application of a noninfectious SARS-CoV-2 biomimetic Mycobacterium smegmatis strain that mimics a positive result in the GeneXpert SARS-CoV-2 Xpert Xpress cartridge. Nucleotide sequences located in genes encoding the RNA-dependent RNA polymerase, the nucleocapsid, and the envelope proteins were used. The resulting biomimetic strain was prepared as a positive proficiency testing control and distributed in South Africa for verification of laboratories before their testing of clinical specimens. Between April and December 2020, a total of 151 GeneXpert instruments with 2532 modules were verified to bring COVID-19 mass testing in South Africa online. An average concordance of 98.6% was noted in the entire laboratory network, allowing identification of false-positive/false-negative results and instrument errors. This noninfectious, easily scalable proficiency testing control material became available within 2 months after the start of the pandemic in South Africa and represents a useful approach to consider for other diseases and future pandemics.

Statistical Analysis of the Performance of Local Veterinary Laboratories in Molecular Detection (rRT-PCR) of Avian Influenza Virus via National Proficiency Testing Performed during 2020-2022.

For the early detection of avian influenza virus (AIV), molecular diagnostic methods such as real-time RT-PCR (rRT-PCR) are the first choice in terms of accuracy and speed in many countries. A laboratory's capability to perform this diagnostic method needs to be measured through external and independent assessment to ensure that the method is validated within the laboratory and in interlaboratory comparison. The Animal and Plant Quarantine Agency of Korea has implemented five rounds of proficiency testing (PT) for rRT-PCR targeting local veterinary service laboratories involved in the AIV national surveillance program from 2020 to 2022. In each round, a portion composed of six or more samples was selected from the entire PT panel consisting of H5, H7, and H9 viruses isolated in Korea and distributed to each participant, and at least one pair of samples was commonly included in each panel for interlaboratory comparison. During the five rounds of PT, a few incorrect and outlying results were detected that required immediate inspection or corrective actions. However, in the quantitative measurement of Ct values, the average standard deviation or coefficient of variation decreased as multiple PT rounds progressed, and a positive correlation between consecutive rounds of PT was observed since 2021. The better consistency or stability in the experimental performance appeared to contribute to the more harmonized results in the latest PTs, and it is assumed that the positive reaction of participants to the challenges of quantitative assessment reports showing their status intuitively might work. We need to continue operating the PT program for local laboratories because they play crucial roles at the front line of the national avian influenza surveillance program, and frequent changes in the human resources or environment for diagnosis in those laboratories are inevitable.

Development of a certified reference material intended to control measurement results accuracy of petroleum products in water and its application for proficiency testing of laboratories through interlaboratory comparative tests

The article considers the notion of oil content as a measurable indicator and provides information on the procedures for measuring the content of petroleum products by IR spectrometry in natural water, drinking water, and treated wastewater. Certified reference materials (CRMs) for petroleum products with certified characteristics of the mass or mass concentration of petroleum products in the matrix were registered in the system of metrological support of measurements. The content of polar petroleum products in the raw material was not taken into account when establishing the certified values of these CRMs; this leads to a significant difference between a certified characteristic of CRMs and the determined indicator of measurement procedures based on the IR spectrometry method. In contrast to CRMs with a certified characteristic in the form of the total content of petroleum products, there was a need to develop CRM for determining the mass concentration of only non-polar and low-polar petroleum products by the IR spectrometry method.Information about the stages of CRM development is presented: selection and preparation of material, investigation of material stability. The results of CRM certification for certified indicators in the range of 0.05–2.00 mg/dm3 are presented. The correctness of these results was confirmed in accredited laboratories by interlaboratory comparative tests.The CRM of mass concentration of non-polar petroleum products in a polar organic solvent GSO 11733–2021 was approved. The metrological characteristics of the CRM were established: the range of permissible certified values is 0.1–3.0 mg/cm3, the permissible relative expanded uncertainty of the certified value for k=2 5 %. The traceability to SI units of the certified CRM value is insured.It has been confirmed that the developed GSO 11733–2021 is intended to control the accuracy of the measurement results of the mass concentration of non-polar petroleum products in drinking water, natural surface water, and treated wastewater using IR spectrometry and can be used for attestation of procedures for measuring the mass concentration of non-polar petroleum products in water by IR spectrometry. The scope of the CRM is environmental protection, quality control of drinking water, natural surface water, and treated wastewater.

Pilot Round of Proficiency Testing Scheme for Determination of Main Quality Characteristics of Oil Cake

The new scheme of proficiency testing of laboratories for determination of main quality characteristics of oil cake was developed. In pilot round was determined such quality characteristics as moisture content (I), mass fraction of fat (II) and mass fraction of crude protein (III). The control sample was prepared from the sample of rapeseed oil cake. It was determined that control sample was sufficiently stable and homogeneous. In the round participated 22 laboratories, which used different test methods. The results were processed by the method described in ISO 13528. Based on these calculations as assigned value for characteristics I and III was chosen robust mean value and for characteristic II - mode of results. As standard deviation of proficiency testing for characteristic I was chosen robust standard deviation and for characteristics II and III was chosen value which is predicted by equation of Horwitz-Thompson. It was determined, that for characteristics I and III different test methods gives equivalent results, so some unsatisfactory results of laboratories can be attributed to laboratory bias. For characteristic II clustering of results according to measurement method in observed. It was established, that outdated standard GOST 13496.15-97 gives higher mass fraction of fat compared to other test methods.

A Comparison of Current Methods for the Determination of Ra-226 and Ra-228 in Water by a Modified Georgia Tech Gamma Method Vs. US Environmental Protection Agency Drinking Water Methodologies.

Radium is a significant source of human radiation exposure both from natural sources (NORM, or Naturally Occurring Radioactive Material) and from technologically enhanced natural radioactive material (TENORM). Gamma analysis for 226Ra and 228Ra in water using high purity germanium (HPGe) detectors was compared with current methods from the US Environmental Protection Agency (EPA) using alpha scintillation and gas proportional counters. Extensive evaluations of a modified version of the original Georgia Tech HPGe method were performed. Known value 226Ra samples from the US Department of Energy (DOE) Mixed-Analyte Performance Evaluation Program (MAPEP) program, mixed 226Ra and 228Ra samples from the Environmental Resource Associates Quality Assurance Program (ERA), and mixed 226Ra and 228Ra samples from the Laboratory Proficiency Testing Program of the International Atomic Energy Agency (IAEA) were used for cross-check comparisons of the modified Georgia Tech method with other methodologies (EPA 903.1 and Ra-05 for 226Ra and 228Ra, respectively). Minimum counting times for our gamma instrumentation to reach a minimum detectable activity (MDA) of 0.04 Bq L-1 were also determined.

Interlaboratory Comparative Tests in Ready-Mixed Concrete Quality Assessment.

Proper quality assessment of ready-mixed concrete, which is currently the principal material for construction, land engineering and architecture, has an impact on the optimisation and verification of correct functioning of individual stages of the production process. According to the European Standard EN 206 “Concrete–Specification, performance, production and conformity”, obligatory conformity control of concrete is carried out by the producer during its production. In order to verify the quality of concrete, investors generally commission independent laboratory units to perform quality assessment of both concrete mix and hardened concrete, which guarantees a high quality of construction works. One of the essential tools for ensuring the quality of test results is the participation of laboratories in the so-called proficiency testing (PT) or inter-laboratory comparisons (ILC). Participation in PT/ILC programmes is, on the one hand, a tool for demonstrating the laboratory’s performance, on the other hand an aid for maintaining the quality of available concrete tests and validating test methods. Positive evaluation is a confirmation of the laboratory’s capability for performing the tests. The paper presents the results of laboratory proficiency tests carried out by means of inter-laboratory comparisons, as shown in the example of quality assessment of ready-mixed concrete for nine participating laboratories. The tests were performed for concrete of the following parameters: strength class C30/37, consistency S3, frost resistance degree F150, and water resistance degree W8. This involved determining consistencies, air content and density of the concrete mix, and compressive strength of hardened concrete. For the evaluation of laboratory performance results, z-score, ζ-score and En-score were applied. The innovation of the proposed study lies in employing both classical and iterative robust statistical methods. In comparison with classical statistical methods, robust methods ensure a smaller impact of outliers and other anomalies on the measurement results. Following the analyses, clear differences were found between the types of detected discrepancy of test results, which occurred due to the nature of individual parameters. For two laboratories, two scores revealed unsatisfactory results for concrete mix consistency. The main reasons can be pouring into the cone-shaped form a concrete mixture that is too dry, or incorrect use of a measuring tool also creating a possibility that the obtained value can be wrongly recorded. Other possible reasons are discussed in the paper. Participation in inter-laboratory comparison programmes is undoubtedly a way to verify and raise the quality of tests performed for concrete mix and hardened concrete, whereas individual analysis of the results allows the laboratory quality system to be improved.

Macroscopic examination of welds: Interlaboratory comparison of nominal data

A statistical technique is developed for interlaboratory comparisons of the macroscopic examination of weld imperfections caused by failures in the welding process. This technique allows comparisons of nominal data with more than two categories which are influenced by two factors (variables). The development is based on two-way categorical analysis of variation (CATANOVA). Decomposition of the between-laboratory variation for a cross-balanced design by these two factors (e.g., laboratory and technician experience) and their interaction, as well as by the categories of the response variable, is proposed. The developed technique was applied to an interlaboratory comparison using 12 images/photographs of welds with five categories of imperfections as the test items for macroscopic examination. The items were distributed to three participating laboratories and examined by both experienced technicians and novices. Analysis of the obtained data showed a consensus between laboratories and between technicians and no interaction between them. It was found also which categories of imperfections were more difficult to identify than others. This technique is applicable for other nominal properties, and can be adjusted for proficiency testing (PT) of laboratories participated in the comparison.

Harmonizing Newborn Screening Laboratory Proficiency Test Results Using the CDC NSQAP Reference Materials.

Newborn screening (NBS) laboratories cannot accurately compare mass spectrometry-derived results and cutoff values due to differences in testing methodologies. The objective of this study was to assess harmonization of laboratory proficiency test (PT) results using quality control (QC) data. Newborn Screening Quality Assurance Program (NSQAP) QC and PT data reported from 302 laboratories in 2019 were used to compare results among laboratories. QC materials were provided as dried blood spot cards which included a base pool and the base pool enriched with specific concentrations of metabolites in a linear range. QC data reported by laboratories were regressed on QC data reported by the Centers for Disease Control and Prevention (CDC), and laboratory’s regression parameters were used to harmonize their PT result. In general, harmonization tended to reduce overall variation in PT data across laboratories. The metabolites glutarylcarnitine (C5DC), tyrosine, and phenylalanine were displayed to highlight inter- and intra-method variability in NBS results. Several limitations were identified using retrospective data for harmonization, and future studies will address these limitations to further assess feasibility of using NSQAP QC data to harmonize PT data. Harmonizing NBS data using common QC materials appears promising to aid result comparison between laboratories.

Assigned value determination by expert laboratory consensus on heavy metals proficiency testing of environmental laboratory 2018

Determination of assigned values is an important stage in proficiency testing schemes in accordance with SNI / ISO 17043: 2010. Assigned value is a reference for determining the laboratory performance status in proficiency test participants. One alternative in determining Assigned value is through expert laboratory consensus. This method has an advantage over the reference value method, namely when there is no certificate reference material (CRM) that matches the proficiency test commodity or the corresponding CRM value is not in place. This study was aimed at determining the assigned value of laboratory proficiency testing of heavy metal parameters by employing the expert laboratory consensus method. In this study, the expert laboratory tested were 20 laboratories included the one in the environmental metrology road map. The laboratories have been accredited according to ISO / IEC 17025. Statistical calculations through Algorithm A, and iteration technique were implemented in this procedure. This will make it easier to determine the assigned value because it does not need to be through the reference value calibration of the CRM value. It was found out that the assigned value in mg/L for each metal, i.e Zn, Fe, Mn and Cd were 0.08; 0.4; 0.3 and 0.06 respectively. It was also shown that the assigned value derived from this expert laboratory consensus were not significantly different from the target value, except for Zn metal that differed from the target by 0.01 mg/L. However, it is important to keep reviewing the competence of the expert laboratory on a regular basis to ensure the validity of the values produced.

Development of interlaboratory comparison test samples and reference materials for the quality assurance of air composition measurements

Introduction. The article presents an approach to the development of interlaboratory comparison test samples and respective reference materials for use in the metrological assurance of measurements of hazardous substances in the ambient air. Materials and methods. Solid and liquid sorbents, as well as air filters were used in the experiments. Measurement methods comprised photometry, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry. Results. An optimized algorithm for developing multi-purpose test samples that can be used for the metrological assurance of a large number of methods for analysing ambient air is presented. Discussion and conclusions. The described approach has been used to develop test samples for laboratory proficiency testing and respective reference materials, which can be used in the certification of procedures for analysing ambient air quality, calibration of measurement instruments, as well as in the internal and external quality control of results obtained during ambient air quality measurements.

Diagnostic Accuracy in Fit-for-Purpose PD-L1 Testing

PD-L1 testing by immunohistochemistry (IHC) has presented significant challenges not only for clinical laboratories, but also for external quality assurance (EQA) entities that provide proficiency testing (PT) for clinical laboratories. Canadian Immunohistochemistry Quality Control (CIQC) has used educational runs to explore approaches to sample design and analysis of results that would enhance patient safety. As PT for predictive biomarkers requires modeling at every level (design of the run, assessment of the run, and reporting of "pass" or "fail") based on "fit-for-purpose" principles, CIQC has applied those principles to PD-L1 PT runs. Each laboratory received unstained slides with TMA tissue cores from 104 randomly selected primary NSCLC and tonsil tissues to test with their current PD-L1 assay. Diagnostic sensitivity and specificity were calculated against designated gold standards based on the "3D" approach (drug-disease-diagnostic assay). Depending on the selection of fit-for-purpose gold standards and also on the selection of what was considered fit-for-purpose cut-off points, great variation in the performance (accuracy) of both companion/complementary diagnostic assays and laboratory developed tests was seen. "Fit-for-purpose" in PT for PD-L1 testing entails that the purpose(s) of each PT run is declared a priori, that the PT program has selected/designated purpose-specific gold standard results for the PT challenge, and that the PT materials for the PT run are designed and constructed to enable calculations of diagnostic accuracy.

Whole genome sequencing used in an industrial context reveals a Salmonella laboratory cross-contamination

In 2013, during a routine laboratory analysis performed on food samples, one finished product from a European factory was tested positive for Salmonella Hadar. At the same period, one environmental isolate in the same laboratory was serotyped Salmonella Hadar. Prior to this event, the laboratory performed a proficiency testing involving a sample spiked with NCTC 9877 Salmonella Hadar. The concomitance of Salmonella Hadar detection led to the suspicion of a laboratory cross-contamination between the Salmonella Hadar isolate used in the laboratory proficiency testing and the Salmonella Hadar isolate found on the finished product by the same laboratory. Since the classical phenotypic serotyping method is able to attribute a serotype to Salmonella isolates with a common antigenic formula, but cannot differentiate strains of the same serotype within the subspecies, whole genome sequencing was used to test the laboratory cross-contamination hypothesis. Additionally, 12 Salmonella Hadar from public databases, available until the time of the event, were included in the whole genome sequencing analysis to better understand the genomic diversity of this serotype in Europe. The outcome of the analysis showed a maximum of ten single nucleotide polymorphisms (SNPs) between the isolates coming from the laboratory and the finished product, and thus confirmed the laboratory cross-contamination. These results combined with all additional investigations done at the factory, allowed to release finished product batches produced and thus circumvented unnecessary food waste and economic losses for the factory.

Brucella abortus RB51 Strain Sent in a Proficiency Testing Panel to Clinical and Public Health Laboratories

In early 2017, a laboratory proficiency testing panel, designed to assess laboratory competency for culture and identification of bacterial organisms, was distributed to clinical and public health microbiology laboratories. The panel included a Brucella abortus RB51 isolate. Although B. abortus RB51 is an attenuated Brucella species strain, it still poses some risk to laboratory personnel, particularly if safety precautions and personal protective equipment are not adequately deployed. The PT event highlighted the challenges that clinical and public health microbiology laboratories face when handling samples that can contain highly transmissible organisms that can lead to laboratory-acquired infections. This review describes the B. abortus RB51 PT event, its associated exposures, and subsequent medical interventions. General considerations for handling Brucella species, including RB51, in the clinical microbiology laboratory are also discussed. Finally, we describe lessons learned from this event, including improving a “culture of safety” in the clinical laboratory.

Canine factor VII deficiency: lessons learned in applying methods-based laboratory proficiency testing.

Canine inherited factor VII deficiency is a mild-to-moderate, inherited coagulopathy that affects several breeds of dog. We identified 2 polymorphisms near the disease-causing F7 gene mutation, one of which interfered with testing in several Beagles by causing allele dropout of the normal, wild-type allele. In the absence of an external proficiency program among veterinary genetic testing laboratories, implementation of an internal proficiency program, which requires 2 independent methods for genotyping dogs at any given locus, was further enhanced by ensuring minimally non-overlapping primer pairs between the 2 assays. After redesign of our clinical tests, all dogs were re-examined, and the correct genotypes were identified. These changes ensure higher accuracy in future testing of the F7 mutation.

Determination of macro, micro, trace essential, and toxic elements in Garcinia cambogia fruit and its anti-obesity commercial products.

Garcinia (Clusiaceae) species are traditionally used as flavoring agents in curries and to cure several human health complications. This study investigated 31 macro, micro, and trace elements in microwave-assisted digested samples of Garcinia cambogia fruit and its anti-obesity commercial products by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometric (ICP-MS) techniques. The methods were also validated using the coefficient of determination (R2 ), limits of detection and quantification (LOD, LOQ), precision (CV%), analysis of certified reference materials, spiking recovery experiments, and participation in an accredited laboratory proficiency test organized by Food Analysis Performance Assessment Scheme (FAPAS). Quality assurance confirmed that the methods were efficient and in accordance with criteria set by the Association of Official Analytical Chemists (AOAC). In the elemental analysis, the analyzed macro, micro, and trace essential elements were present in appreciable concentrations, which could meet the human nutritional requirements. Traces of toxic elements were within safe limits. From the results of the current study, the fruit and its commercial products could be considered potential sources of mineral elements without posing any threats to consumers. © 2018 Society of Chemical Industry.

Performance evaluation and study on open assembly line system in medical laboratory

Objective To investigate the advantages and continuous optimization of laboratory automation system through analysis and assessment of the core data and performance after the application of open assembly line. Methods Collect the data of biochemical and immunoassay in Shuguang Hospital attached to Shanghai University of Traditional Chinese Medicine from April to October 2017. (1) Cost analysis of the assembly line schemes; (2) Analysis of workflow before and after the application of assembly line; (3) Analysis of the volume of samples collecting before and after the application of assembly line; (4) Analysis of TAT data before and after the application of assembly line; (5) Analysis of staffs allocation before and after the application of assembly line; (6) Analysis of samples rechecking before and after the application of assembly line . Results (1) Open assembly line costs least on hardware(8 million) and site among various projects; (2) Inspection process is greatly simplified after the application of assembly line; (3) The samples′ volume of biochemical and immunoassay inspection were reduced by 31.85%; (4) The items′ test cycle decreases after the application of assembly line, the average TAT is reduced by 32 minutes; (5) Staffs for samples pretreatment can be reduced by 50% after the application of assembly line, and the quantity of operators does not change; (6) The number of re-check samples increase except the gray zone and critical values, which ensures the reliability of the results. Conclusion To analyze the core data and to evaluate the performance, the laboratory improve on detection cycle, staffs, and test efficiency.(Chin J Lab Med, 2018, 41: 680-684) Key words: Automation, laboratory; Automatic data processing; Employee performance appraisal; Laboratory proficiency testing

Differences in the accuracy of test methods in the field of testing aggregate and determination of their causes

A The article is based on the authors’ many years of experience in providing laboratory proficiency testing including organization of proficiency testing by interlaboratory comparison. In the introduction are compared the basic tests in the field of aggregates, based on their coefficient of variation. Another part details the influence of each testing stage (sampling, sample preparation and the test itself) on the accuracy of the test results and proposes possible measures to reduce their variance.

High rates of variation in HLA-DQ2/DQ8 testing for coeliac disease: results from an RCPAQAP pilot program

AimCoeliac disease(CD) is a highly prevalent, gluten-dependent, autoimmune enteropathy. While the diagnosis is based on serological and histological criteria, genotyping of the human leucocyte antigens (HLA) DQ2 and DQ8 has...