Comparison of the Japan Society of Clinical Chemistry reference method and CDC method for HDL and LDL cholesterol measurements using fresh sera

Objectives

In 2009, the Japan Society of Clinical Chemistry (JSCC) recommended a reference method for the measurement of serum high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels. This automated method uses cholesterol esterase-cholesterol dehydrogenase to measure cholesterol levels in fractions obtained after ultracentrifugation and dextran sulfate/magnesium chloride precipitation. In the present study, using fresh samples, we compared the LDL-C and HDL-C levels measured using this method with those measured using the traditional Centers for Disease Control and Prevention (CDC)-beta-quantification (BQ) method.

Design

and methods: Using both the JSCC and CDC-BQ methods, LDL-C/HDL-C levels were measured in 47 non-diseased and 126 diseased subjects, whose triglyceride levels were lower than 11.29 ​mmol/L (1000 ​mg/dL).

Results

For LDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.991x + 0.009 ​mmol/L; r ​= ​0.999; and Sy/x ​= ​0.025 ​mmol/L, where x is the mean LDL-C level measured using the CDC-BQ method. Similarly, for HDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.988x + 0.041 ​mmol/L, r ​= ​0.999, and Sy/x ​= ​0.019 ​mmol/L, where x is the mean HDL-C level measured using the CDC-BQ method.

Conclusions

The JSCC method agreed with the CDC-BQ method in cases of both non-diseased and diseased subjects, including those with dyslipidemia.

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Using both the JSCC and BQ methods, LDL-C/HDL-C levels were measured.

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The JSCC method agrees with the BQ method.

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The JSCC reference method is an accurate, simple, and automatable method.

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The JSCC method is suitable for quantitative analysis of LDL-C and HDL-C levels.

Reference method for off-line analysis of nitrogen oxides in cell culture media by an ozone-based chemiluminescence detector

Nitric oxide (NO) and its by-products are important biological signals in human physiology and pathology particularly in the vascular and immune systems. Thus, in situ determination of the NO-related molecule (NO_x) levels using embedded sensors is of high importance particularly in the context of cellular biocompatibility testing. However, NO_x analytical reference method dedicated to the evaluation of biomaterial biocompatibility testing is lacking. Herein, we demonstrate a PAPA-NONOate-based reference method for the calibration of NO_x sensors. After, the validation of this reference method and its potentialities were demonstrated for the detection of the oxidative stress-related NO secretion of vascular endothelial cells in a 3D tissue issued from 3D printing. Such NO_x detection method can be an integral part of cell response to biomaterials. Graphical abstract.

Evaluation of the commercial AD fosfomycin test for susceptibility testing of multidrug-resistant Enterobacterales and Pseudomonas aeruginosa

OBJECTIVES

To compare fosfomycin susceptibility testing with the commercial agar dilution (AD) test, AD Fosfomycin (Liofilchem, Roseto degli Abruzzi, Italy) and the reference AD method, using a collection of multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa clinical isolates.

METHODS

The collection included 119 carbapenemase-producing Enterobacterales, 53 Enterobacterales producing acquired AmpC-type and/or extended-spectrum β-lactamases and 38 carbapenemase-producing P. aeruginosa, including representatives of different high-risk clones. AD Fosfomycin and AD reference method (ISO 20776-1:2019) were performed starting from the same microbial suspension. Results were interpreted according to EUCAST clinical breakpoints (10.0). Essential agreement (EA), category agreement (CA) and error rates were calculated as described by the International Organization for Standardization.

RESULTS

Of 172 Enterobacterales, 143 (83.1%, including 92.9% (52 of 56) of the NDM-producers and 84.2% (48 of 57) of the KPC-producers) were susceptible to fosfomycin using reference AD. A CA of 91.9% (158 of 172; 95% CI 87.1%-95.3%) and an EA of 92.5% (136 of 147; 95% CI 87.4%-96.0%), respectively, were calculated for the commercial AD Fosfomycin test, with 9.8% (14 of 128) of major errors and no very major errors (0 of 29). Overall, 86.8% (33 of 38) of P. aeruginosa showed a fosfomycin MIC ≤128 mg/L using reference AD. An EA of 84.8% (95% CI 66.3%-92.0%) was calculated for the commercial AD Fosfomycin test, with a CA of 100% (95% CI 93.6%-100%) when considering a tentative breakpoint at 128 mg/L.

CONCLUSIONS

AD Fosfomycin showed an overall good concordance compared with reference AD.

Multicentre testing of the EUCAST broth microdilution reference method for MIC determination on Mycobacterium tuberculosis

OBJECTIVES

The first objective of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) subcommittee for antimycobacterial susceptibility testing (AMST), launched in 2016, was to set a reference method for determining the MICs of antituberculous agents, since many protocols are used worldwide and a consensus one is needed for the determination of microbiological breakpoints.

METHODS

During 2017 and 2018, MIC determination protocols were evaluated prospectively in a multicentre study within the four AMST laboratories. MIC results were obtained for isoniazid, levofloxacin and amikacin on the reference strain Mycobacterium tuberculosis H37Rv ATCC 27294. Broth microdilution (BMD) in Middlebrook 7H9 and solid medium dilution (SMD) in Middlebrook 7H10 were performed using two inoculum concentrations. MICs were interpreted with regard to visual and 99% inhibition after 7, 14 or 21 days of incubation for BMD and 21 days for SMD.

RESULTS

Following the EUCAST reference protocol, intra- and inter-assay agreements were within ±1 MIC dilution for >95% of the observations for the three drugs in both methods. MIC values, presented as MIC mode (range) for BMD and SMD respectively, were: 0.03 (0.015-0.06) mg/L and 0.12 (0.06-0.25) mg/L for isoniazid, 0.25 mg/L (0.25-0.5) and 0.5 mg/L (0.12-0.5) for levofloxacin, and 0.5 mg/L (0.5-1.0) and 0.5 mg/L (0.5-1.0) for amikacin.

CONCLUSIONS

Both SMD and BMD were reproducible and eligible as a reference method for MIC determination of the Mycobacterium tuberculosis complex (MTBC). BMD was finally selected as the EUCAST reference method. From now on it will be used to set epidemiological cut-off values and clinical breakpoints of new and old antituberculous agents.

Antimicrobial susceptibility testing of Mycobacterium tuberculosis complex isolates - the EUCAST broth microdilution reference method for MIC determination

SCOPE

Several methods are used worldwide for antibiotic susceptibility testing (AST) for the Mycobacterium tuberculosis complex (MTBC). The variability in the results obtained with these methods hampers setting epidemiological cut-off (ECOFF) values and clinical breakpoints according to EUCAST guidelines. Methods for susceptibility testing and determination of the minimal inhibitory concentrations (MICs) need to be standardized for MTBC isolates for old and new agents. Our objective was to establish a standardized reference method for MIC determination for MTBC.

METHODS

The EUCAST antimycobacterial susceptibility testing subcommittee (AMST) compared protocols of MIC determination with regard to medium, inoculum preparation, antituberculous agent preparation, incubation, reading of the results and interpretation.

RECOMMENDATIONS

The EUCAST reference method of MIC determination for MTBC is the broth microdilution method in Middlebrook 7H9-10% OADC medium. The final inoculum is a 10⁵ CFU/mL suspension, obtained from a 10^-2 dilution of a 0.5 McFarland suspension prepared after vortexing bacterial colonies with glass beads before suspending them in sterile water. The culture is maintained in a U-shaped 96-well polystyrene microtitre sterile plate with a lid incubated at 36° ± 1°C. Reading is done using an inverted mirror as soon as the 1:100 diluted control (i.e. 10³ CFU/mL suspension) shows visual growth. The MIC, expressed in mg/L, is the lowest concentration that inhibits visual growth. Mycobacterium tuberculosis H37Rv ATCC 27294 is used as the reference strain and its targeted MIC values are within the range 0.03-0.12 for isoniazid, 0.12-0.5 for levofloxacin and 0.25-1 mg/L for amikacin.

CONCLUSIONS

The EUCAST reference method for MTBC was endorsed by EUCAST after public consultation and will from now on be used to define EUCAST ECOFFs and clinical breakpoints. This reference method is not primarily intended to be used under routine conditions and the AST methods will need to be calibrated against this reference method to be used with EUCAST breakpoints.

Development of a multiple regression model to calibrate a low-cost sensor considering reference measurements and meteorological parameters

Low-cost air quality sensors are widely used to improve temporal and spatial resolution of air quality data. In Lima, Peru, only a limited number of reference air quality monitors have been installed, which has led to a lack of data for establishing environmental and health policies. Low-cost technology is promising for developing countries because it is small and inexpensive to operate and maintain. However, considerable work remains to be done to improve data quality. In this study, a low-cost sensor was installed with a reference monitor station as the first stage for the calibration process, and a multiple regression model was developed based on reference measurements as an outcome variable using sensor data, temperature, and relative humidity as the predictive parameters. The results show that this particular technology exhibits a promising performance in measuring PM_2.5 and PM₁₀ (particulate matter with diameter aerodynamic less than 2.5 μm and 10 μm, respectively); however, the correlation for PM_2.5 appears to be better. Temperature and relative humidity data from the sensor were only partially analyzed due to the evident low correlation with the reference meteorological data. The objective of this study is to begin analyzing the performance of low-cost sensors that have already been introduced to the Peruvian market and selecting those that perform better to provide for informed decision-making.

Comparison of potential higher order reference methods for total haemoglobin quantification-an interlaboratory study

The total haemoglobin (Hb) concentration in blood is one of the most frequently measured analytes in clinical medicine because of its significance for evaluating the health state of a human. The spectrophotometric cyanmethaemoglobin (HiCN) method is the internationally accepted conventional reference method to determine this biomarker. It is frequently used in clinical routine diagnostics but is not traceable to the International System of Units and thus does not meet highest metrological demands. A further critical issue is the toxicity of the necessary potassium cyanide. Different methods to solve these problems are reported here. They all were validated against the HiCN method in an interlaboratory comparison by measuring the total Hb concentration present in the certified reference material JCCRM 912-2M. Methods considered were the spectrophotometric alkaline haematin detergent (AHD) method as well as several isotope dilution (ID)-based approaches. The latter include inductively coupled plasma mass spectrometry (ICP-MS), species-specific (SS) ICP-MS, organic MS and Raman spectrometry. Graphical abstract ᅟ.