Quality Control Range Research Articles

Improving quality control procedures for the measurement of total daily energy expenditure using the two-point doubly labeled water method.

The precision of the doubly labeled water (DLW) method is determined by the precision and accuracy of the isotopic measurements. Quality control (QC) procedures to mitigate sample variability require additional measurements if sample duplicates differ more than a factor of instrument precision. We explored the effect of widening QC ranges on total daily energy expenditure (TDEE) determined using the two-point sampling method. We screened DLW data from 121 individuals for instances where samples were analyzed more than twice using our existing QC criteria (±2.0 per mil [δ] for 2H and ±0.5 δ for 18O). We then applied wider QC ranges for accepting duplicate measures and recalculated TDEE. Widening the 2H QC range to ±10.0 δ in samples collected on the first day (most enriched) and to ±5.0 δ in samples collected on the final day (less enriched) produced almost identical mean TDEE compared to the originally calculated TDEE (2684 ± 508 vs. 2687 ± 512 kcal/day, p= 0.40). There was a strong correlation with the originally calculated TDEE (r2=0.97, p< 0.001). Expanding the 2H QC range to ±10.0 δ for samples collected on the first day and ±5.0 δ for samples collected on the final day provides similar mean TDEE results. These findings may help DLW labs optimize QC criteria and reduce analytical costs.

Quality control on vibrator ground force in land vibroseis acquisition

Many quality control (QC) methods are used to monitor the output force from seismic vibrators. These QC tools usually provide the vibrator output force in three aspects — fundamental force, phase, and harmonic distortion — to measure the quality of the ground force compared with the predetermined sweep. As the vibrator works on challenging earth surfaces, such as unconsolidated ground surfaces, the peak harmonic distortion, a key vibrator QC parameter, always exceeds its QC threshold. This necessitates a vibrator reshoot and thereby a degradation of productivity. The purpose of this paper is to demonstrate that in unconsolidated ground surface areas a new setting of the harmonic cutoff frequency on a vibrator controller is recommended. This new setting reduces the unnecessary harmonics around 200 Hz so that the peak harmonic distortion is controlled in the required QC range. Therefore, unnecessary vibrator reshoots can be avoided, leading to improved productivity.

Sulbactam-durlobactam susceptibility test method development and quality control ranges for MIC and disk diffusion tests.

Sulbactam-durlobactam is a β-lactam/β-lactamase inhibitor combination developed to treat hospital-acquired and ventilator-associated bacterial pneumonia caused by Acinetobacter baumannii-calcoaceticus complex (ABC). Durlobactam is a diazabicyclooctane β-lactamase inhibitor with potent activity against Ambler classes A, C, and D serine β-lactamases and restores sulbactam activity against multidrug-resistant ABC. Studies were conducted to establish sulbactam-durlobactam antimicrobial susceptibility testing methods for both broth microdilution minimal inhibitory concentration (MIC) and disk diffusion tests as well as quality control (QC) ranges. To establish the MIC test method, combinations of sulbactam and durlobactam were evaluated using a panel of genetically characterized A. baumannii isolates which were categorized as predicted to be susceptible or resistant based on the spectrum of β-lactamase inhibition by durlobactam. MIC testing with doubling dilutions of sulbactam with a fixed concentration of 4 µg/mL of durlobactam resulted in the greatest discrimination of the pre-defined susceptible and resistant strains. Similarly, the sulbactam/durlobactam 10/10 µg disk concentration showed the best discrimination as well as correlation with the MIC test. A. baumannii NCTC 13304 was selected for QC purposes because it assesses the activity of both sulbactam and durlobactam with clear endpoints. Multi-laboratory QC studies were conducted according to CLSI M23 Tier 2 criteria. A sulbactam-durlobactam broth MIC QC range of 0.5/4-2/4 µg/mL and a zone diameter QC range of 24-30 mm were determined for A. baumannii NCTC 13304 and have been approved by CLSI. These studies will enable clinical laboratories to perform susceptibility tests with accurate and reproducible methods.

Sulopenem Disk Development, Quality Control Range, and MIC to Disk Result Correlation for Enterobacterales Isolates.

Sulopenem disk masses of 2, 5, 10, and 20 μg were evaluated by susceptibility testing isolates by broth microdilution and disk diffusion. A 2-μg disk was chosen, and error-rate bounding analysis in accordance with Clinical and Laboratory Standards Institute (CLSI) guideline M23 was conducted using a proposed sulopenem susceptible/intermediate/resistant (S/I/R) interpretive criterion of ≤0.5/1/≥2 μg/mL. Among the evaluated Enterobacterales (n = 2,856), very few interpretive errors were observed (no very major errors and only one major error). An eight-laboratory quality control (QC) study was performed using the 2-μg disk, and 99.0% (470/475) of results were within a 7-mm range of 24 to 30 mm. Results were similar by disk lot and media, and no outlier sites were observed. A sulopenem 2-μg disk QC range for Escherichia coli 29522 of 24 to 30 mm was established by the CLSI. A 2-μg sulopenem disk performs accurately and reproducibly for testing of Enterobacterales.

Verification of Assayed Blood Gas Quality Control Ranges.

Blood gas quality control (QC) is an essential and mandatory part of a laboratory's quality plan. The acceptable QC range should be 2 SD from the mean value. The use of assayed QC material does not negate the responsibility of the laboratory to calculate the mean and 2 SD ranges of QC measurements for verification. Verifying assayed QC ranges is a Clinical Laboratory Improvement Amendment (CLIA) requirement. This study shows the results of assayed QC mean and 2 SD range verification from a blood gas analyzer. QC data from a blood gas analyzer were compared to manufacturer-provided mean and ranges. The percent difference between the measured mean and the manufacturer-provided mean was calculated to assess agreement. The measured SD was used to determine how many SD the manufacturer-provided ranges were from the measured mean. The largest difference in mean values was 2.27% > the manufacturer-provided mean. Forty-eight percent of all mean value comparisons showed a difference of 0%, and 71% were < 1%. The manufacturer-provided ranges were considerably wider than the measured 2 SD range, ranging from 2.4-75 SD. None of the manufacturer-provided ranges were deemed acceptable for clinical use. Our analysis validates the CLIA mandate and American Association for Respiratory Care Clinical Practice Guideline recommendation that laboratories must verify manufacturer-provided QC means and ranges and adjust QC means and ranges to match the performance of their blood gas analyzer.

A Multilaboratory, Multicountry Study To Determine Bedaquiline MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing.

The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated. Mycobacterium tuberculosis H37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37Rv M. tuberculosis reference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide.

Pefloxacin as a Surrogate Marker for Fluoroquinolone Susceptibility for Salmonella typhi: Problems and Prospects.

Pefloxacin as a Surrogate Marker for Fluoroquinolone Susceptibility for Salmonella typhi: Problems and Prospects.

Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilum to nine antimicrobials

A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for the fish pathogens Flavobacterium columnare and F. psychrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658 against 10 antimicrobials (ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, ormetoprim/sulfadimethoxine, oxolinic acid, oxytetracycline, and trimethoprim/sulfamethoxazole) in diluted (4 g l-1) cation-adjusted Mueller-Hinton broth incubated at 28 and 18°C for 44-48 and 92-96 h, respectively. QC ranges were set for 9 of the 10 antimicrobials. Most of the minimal inhibitory concentration (MIC) distributions (16 of 18, 9 drugs at both temperatures) for A. salmonicida ATCC 33658 were centered on a single median MIC ± 1 two-fold drug dilution resulting in a QC range that spanned 3 dilutions. More of the E. coli ATCC 25922 MIC distributions (7 of 16) were centered between 2 MIC dilutions requiring a QC range that spanned 4 dilutions. A QC range could not be determined for E. coli ATCC 25922 against 2 antimicrobials at the low temperature. These data and their associated QC ranges have been approved by the Clinical and Laboratory Standards Institute (CLSI), and will be included in the next edition of the CLSI M49-A Guideline. This method represents the first standardized reference method for testing fish pathogenic Flavobacterium spp.

Evaluation of Fixed Quality Control Range of Bayer Rapidpoint 400 Blood Gas and Electrolyte Analyzer with Six Sigma Metrics

Bayer Rapidpoint 400 analyzer for point of care testing (POCT) uses fixed quality control (QC) range even when the lot number of a cartridge for quality control changes. To evaluate the fixed QC range recommended by the manufacturer, we analyzed internal QC data of 9 analyzers with Six Sigma metrics. We investigated QC data of 9 analyzers over 5 months from May to September, 2004 for 8 parameters (pH, pCO(2), pO(2), Na(+), K(+), iCa(++), Cl(-), and glucose). One hundred eighty six groups of QC data were analyzed with capability index (C(p)=total allowable error (TEa)/3 standard deviation (SD)) and capability index considering bias (C(pk),=(TEa-bias)/3 SD). Acceptability was evaluated with criteria of 1.33 C(pk), 4 sigma level or quality criteria of the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88). In 80.7% (150 of 186 groups), both C(p) and C(pk) were at or above 1.33, which indicated that the use of fixed QC range was adequate. In 19.3% (36 of 186 groups), C(pk) was below 1.33, which indicated the inadequacy of fixed QC range. Among them 14.5% (27 of 186 groups) showed C(p) below 1.33, indicating that the errors had a random factor and 4.8% (9 of 186 groups) had C(p) at or above 1.33, indicating that the errors had a systematic factor. The quality criteria mandated by CLIA '88 was satisfied in about 80% of study groups using fixed QC ranges, but in about 20%, more strict instrument maintenance and specimen handling by operators, and quality improvement of QC materials by manufacturer was required.

Revision of linezolid disk diffusion quality control guidelines for testing Staphylococcus aureus ATCC 25923: an independent seven-laboratory trial

The accuracy of the published disk diffusion quality control (QC) range for linezolid for Staphylococcus aureus ATCC 25923 has been reported to be problematic, prompting a multicenter study to determine if revision was necessary. Five out of seven laboratories reported values outside the current QC range. Three participants had significant (13.3-60.0%) 'unacceptable' results with zones smaller than the established range. Overall, a range of 21-32 mm was shown (82.4% within the NCCLS published range). A revision (25-31 mm; 95.7% of results) of the QC range is necessary when testing S. aureus ATCC 25923 against linezolid.

Re-evaluation of quality control guidelines for gatifloxacin and garenoxacin (BMS284756) when susceptibility testing Haemophilus influenzae and Streptococcus pneumoniae

An eight laboratory M23-A2 quality control (QC) study was performed for the re-evaluation of gatifloxacin, a new fluoroquinolone, using disk diffusion tests against Streptococcus pneumoniae ATCC 49619. The study also re-evaluated garenoxacin, a novel investigational des-F(6)-quinolone, using disk diffusion tests against S. pneumoniae ATCC 49619 and broth MIC for Hemophilus influenzae ATCC 49247. The gatifloxacin zone diameter results for S. pneumoniae did not indicate a need for QC range modification (26-34 mm; 98.3% of results); however, the garenoxacin zone diameters did demonstrate a need for a minor modification (1 mm; 26-34 mm; 96.3% of reported results). The broth MIC results for H. influenzae showed that 83.1% of the results were at the upper limit of the current range (0.008 μg/ml) published by the National Committee for Clinical Laboratory Standards (NCCLS). The proposed correction could either be 0.002-0.015 μg/ml or 0.004-0.015 μg/ml, each encompassing 100.0% of reported results (prior and current studies). All MIC results for control drugs, levofloxacin and moxifloxacin (disks) or gatifloxacin and clarithromycin (MIC), were within published NCCLS ranges.

Longitudinal quality control methodology for the quantitative ultrasound Achilles+ in clinical trial settings.

Appropriate quality assurance (QA) and quality control (QC) procedures have been well developed and validated for dual X-ray absorptiometry (DXA), and are widely applied in multicenter clinical trials to monitor device stability used to check the treatment effects on bone mineral density. This is not yet the case for quantitative ultrasound (QUS) technology, for which no QC approaches have yet been fully tested. The first Achilles (GE-Lunar Corporation, Madison, WI, USA) has been on the market for 10 years (1991). The goal of this study was to develop the QC methodology for the QUS Achilles+ device using its past/current experience (log and maintenance files.) as well as by integrating the progress made over the last years in the ultrasound domain so as to better understand the influence of temperature on ultrasound parameters. Because of the lack of confidence in the external black rubber phantom used in daily QC with the Achilles+, to monitor the device stability, we selected several QC parameters known to be influenced by potential malfunctions as experienced by the maintenance department of GE-Lunar company as well as the physical approach. These are phantom temperature-adjusted speed of sound (PSOS-TC) and broadband ultrasound attenuation (PBUA-TC), water speed of sound error (WSE), water spectrum slope (WSS) and water gain (WG). We used four Achilles+ devices perfectly stable during their entire QC range, to calculate the optimum thresholds (based mostly on 95% confidence interval) for each of these parameters as well as the precision for the in vitro SOS and BUA. An additional not fully stable Achilles device has been used to run a QC procedure example. The precision expressed as the CV was 0.22% and 0.65% for the PSOS-TC and PBUA-TC, respectively. The alarm thresholds used for QC process are +/- 0.6%, +/- 1.9%, +/- 6.8 m/s, +/- 5.3% and +/- 7.3% for the PSOS-TC, PBUA-TC, WSE, WSS and WG, respectively. Applying a logical approach on the impact of each parameter on each other as well as their respective reactivity to malfunctions, we build a QC process flowchart meant to detect real malfunction in the daily QC. We found that in case of real malfunctions, the in vivo SOS should be decreased by 1.33 m/s for each 1 m/s increase in WSE. Unfortunately, in vivo BUA can not be adjusted when real malfunction occurs. Nevertheless, the BUA can be qualified as bad quality data and excluded from the medical interpretation. Using the currently available phantom and parameters, the best possible QC procedures to detect long-term drift in the daily QC of the Achilles+ was developed. To fully validate our approach and gain confidence in the defined limits it is our plan to apply this QC processing to a higher number of QUS devices.

Stratus CS Stat Fluorometric Analyzer

Stratus CS Stat Fluorometric Analyzer

Validation of cefditoren MIC quality control ranges by a multi-laboratory study (2001)

The potency of cefditoren has been well documented to include broad coverage against both Gram-positive and Gram-negative organisms including species causing community-acquired respiratory tract infections. The accuracy of in vitro test results has been questioned due to debate over inconsistencies in quality control (QC) recommendations published by the National Committee for Clinical Laboratory Standards (NCCLS). Previous studies have recommended conflicting and generally broad MIC dilution ranges for several commonly used QC organisms. This study used NCCLS recommended guidelines to re-evaluate the MIC ranges using a seven laboratory M23-A2 design. The results of this multi-laboratory investigation leads to the proposal of the following QC range recommendations for cefditoren: Streptococcus pneumoniae ATCC 49619 (0.016–0.06 μg/mL); Haemophilus influenzae ATCC 49247 (0.06–0.25 μg/mL); Escherichia coli ATCC 25922 (0.12–1 μg/mL); and Staphylococcus aureus ATCC 29213 (0.25–1 μg/mL). These proposed ranges validate those suggested previously for E. coli and the problematic H. influenzae, but a three log 2 dilution range may be sufficient for S. aureus and S. pneumoniae.

Evaluation of microparticle enzyme immunoassay against HPLC-mass spectrometry for the determination of whole-blood tacrolimus in heart- and lung-transplant recipients

Objectives: Tacrolimus is an immunosuppressant drug with a narrow therapeutic window and thus requires therapeutic drug monitoring. This study evaluates the suitability of the second-generation microparticle enzyme immunoassay (MEIA II) against a specific method, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), for the measurement of tacrolimus in both heart- and lung-transplant groups. A secondary objective was to investigate the effect of tacrolimus concentration on MEIA II measurement. Methods: The HPLC-MS assay was conducted as per our reported method and MEIA II performed according to manufacturer’s instructions. Quality-control samples at 5, 11, and 22 μg/L were run in each batch to ensure assay integrity in both methods. Multiple trough samples from 18 heart patients ( n = 126) and 17 lung patients ( n = 203) were analyzed. Results: The inter-batch imprecision and analytical recovery over the quality-control range by HPLC-MS ( n = 12) was <6% and 98.2% to 104%, respectively, and by MEIA II ( n = 16) <15% and 92.0% to 99.1%, respectively. The mean overestimation by MEIA II between the two methods for heart- and lung-transplant patient samples was found to be 9.9% (range: −37.4–45.4%) and 13.2% (range: −29.2–64.3%), respectively. Stratification of these data based on the tacrolimus concentration determined by MEIA II, yielded no statistically significant differences in bias between concentration subgroups within the clinically relevant range ( p > 0.4). However, a statistically significant difference was detected between the highest concentration subgroup (>20.0 μg/L) and lower concentration subgroups in both transplant populations ( p < 0.05). Conclusions: This study suggests that where HPLC-MS is not available, MEIA II may be suitable for the therapeutic drug monitoring of tacrolimus in heart- and lung-transplant recipients. However, the clinical importance of the observed mean bias, considering the wide range in overestimation in heart- and lung-transplant patient samples, is yet to be determined.

Development of gemifloxacin in vitro susceptibility test methods for gonococci including quality control guidelines

Gemifloxacin (formerly SB-265805 or LB20304a) is a new fluoronapthyridone with documented activity against Gram-positive and -negative organisms. The activity of gemifloxacin was tested against 150 Neisseria gonorrhoeae strains, using reference agar dilution, standardized disk diffusion, and Etest (AB BIODISK, Solna, Sweden) methods. Gemifloxacin was very potent against ciprofloxacin (CIPRO)-susceptible strains (MIC 90, 0.008 μg/ml) but was significantly less active against the CIPRO-resistant gonococci (MIC 90, 0.12 μg/ml). Etest and reference agar dilution MIC results showed excellent correlation ( r = 0.96), and 98.7% MICs were within ± one log 2 dilution. Agar dilution MICs were also compared to zone diameters obtained using gemifloxacin 5-μg disks; and complete intermethod categorical agreement (100%) was achieved applying breakpoints proposed as follows: ≤0.25 μg/ml (zone, ≥ 25 mm) for susceptible and ≥1 μg/ml (zone, ≤21 mm) for resistant. Gemifloxacin MIC and disk diffusion test quality control (QC) ranges were established for N. gonorrhoeae ATCC 49226. Data were collected from ≥ seven laboratories, three GC agar medium lots for both agar MICs and disk methods, and two lots each of the 5- and 10-μg disks. The proposed MIC QC range was 0.002 to 0.016 μg/ml and the calculated mm zone ranges (median ± 0.5× average mm range) for both disks were similar, but contained only 88.1 to 91.9% of participant results. To achieve the acceptable ≥ 95% of all study results within range, a 43 to 54 mm limits (5-μg disks) were necessary. The excellent broad-spectrum activity and a low reported adverse effects profile of gemifloxacin shows a potential for treatment of fluoroquinolone-resistant gonorrhea.

Determination of MIC Quality Control Ranges for ABT-733, a Novel Ketolide Antimicrobial Agent

Determination of MIC Quality Control Ranges for ABT-733, a Novel Ketolide Antimicrobial Agent

Anti-streptococcal activity of SB-265805 (LB20304), a novel fluoronaphthyridone, compared with five other compounds, including quality control guidelines

SB-265805 (formerly LB20304) is a novel C-7 pyrrolidine-substituted naphthyridone that has a broad spectrum of activity, especially against Gram-positive cocci. SB-265805 activity was compared with ciprofloxacin, grepafloxacin, moxifloxacin, sparfloxacin, and penicillin against 599 Streptococcus spp. isolated recently from more than 30 medical centers in North and South America. These included 70 isolates with decreased susceptibility to recently released fluoroquinolones (levofloxacin MIC, ≥4 μg/mL). All strains were tested by reference microdilution methods in lysed horse blood-supplemented Mueller–Hinton broth. Sixteen percent of 148 β-haemolytic streptococci (strains of gr. B and C) were not susceptible to penicillin, whereas 38% and 42% of viridans group streptococci and Streptococcus pneumoniae were resistant to penicillin, respectively. SB-265805 potency against 301 pneumococci (MIC 90, 0.06 μg/mL) was fourfold more active than moxifloxacin and was ≥eightfold more potent than other quinolones. Against β-haemolytic streptococci, SB-265805 and moxifloxacin were the most active (MIC 90, 0.06 and 0.25 μg/mL, respectively), whereas sparfloxacin, grepafloxacin, and ciprofloxacin (MIC 90, 0.5–1 μg/mL) were less potent. SB-265805 MICs versus viridans group streptococci (MIC 90, 0.12 μg/mL) were fourfold lower than sparfloxacin or grepafloxacin, and twofold more active than moxifloxacin. A nine-laboratory quality control (QC) protocol conforming to NCCLS M23-T3 guidelines demonstrated a modal SB-265805 MIC of 0.016 μg/mL for S. pneumoniae ATCC 49619 (proposed QC range, 0.008 to 0.03 μg/mL). The SB-265805 disk (5-μg) QC range was 28–34 mm (97.3% of qualifying results). In general, SB-265805 in vitro activity against Streptococcus species was superior to sparfloxacin, grepafloxacin, and moxifloxacin and markedly greater than ciprofloxacin. This degree of antimicrobial potency warrants further investigation of this newer drug for its potential human clinical application against streptococcal infections.

Interpretive criteria and quality control guidelines for lomefloxacin and meropenem in susceptibility tests of Haemophilus influenzae using Haemophilus test medium.

Lomefloxacin and meropenem were tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Haemophilus influenzae using Haemophilus test medium (HTM). Interpretive criteria were established by using triplicate testing of 102 representative H. influenzae strains. Only a susceptible category was proposed for lomefloxacin (greater than or equal to 22 mm and less than or equal to 2 micrograms/ml) and meropenem (greater than or equal to 13 mm and less than or equal to 4 micrograms/ml) due to the lack of resistant isolates. QC range for H. Influenzae ATCC 49247 were established using multiple HTM agar and broth base lots, three disk lots for each drug, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards M23-T guideline.