Major Error Rates Research Articles

"So You Made a Mistake" - The Path Forward Through Surgical Pathology Errors by Extreme Ownership and a Focus on the Patient.

Our goal for medicine is to make zero mistakes, yet the reality is that mistakes are an unfortunate part of medical practice. And when it comes to surgical pathology, it is a special case where the diagnostic "bottom line" is provided starkly and directly for all to see in the final diagnosis of the pathology report. When this diagnosis is wrong, particularly when it has serious adverse consequences for the patient, the resulting physical, mental, and emotional effects on patient, provider, pathologist, and health care system can be extremely serious. Head and neck surgical pathology, based on large second review-type studies, is a subspecialty area with average rates of major diagnostic error, but with potential for severely negative impacts on patients. Studies have shown between 1% and 7% major error rates for head and neck practice. How then, as the pathologist, can we react to and manage things when we have made a serious diagnostic mistake? Through personal experience over more than two decades, the hard-won answer is through extreme ownership and a focus on the needs of the patients, who, in the words of William J. Mayo, should have their "needs come first". The emotional impact on us as pathologists and on the clinicians we work with should also be acknowledged and managed. This article will serve as a thorough and open examination of these mistake scenarios and, focusing specifically on diagnostic errors, serve as a practical guide for what you can do, moving forward, to "make things right" to the best of your ability.

Evaluation of the Colistin HiMIC Plate Kit for Colistin Susceptibility Testing of Klebsiella pneumoniae.

Colistin HiMIC Plate Kit (HiMedia Laboratories), a new commercial broth microdilution (BMD) test for colistin susceptibility testing was evaluated. BMD according to ISO standard 20776-1 (2019) with two-fold dilutions from 128 to 0.125 mg/L was used as a reference method. The colistin reference MICs (minimal inhibitory concentration) ranged from 0,25 to 128 mg/L with 15 (20.5%; 15/73) isolates having colistin reference MICs close to the current EUCAST breakpoint (MICs of 2, 4, and 8 mg/L). The study assessed the compliance of a commercial kit with the CLSI criteria, including categorical agreement (CA) and essential agreement (EA ≥90%), very major error (VME rate) <3%, and major error (ME) rate <3%. On 73 carbapenemase-producing Klebsiella pneumoniae isolates Colistin HiMICTM Plate Kit showed CA and EA of 100% (73/73; 95% CI 0.97-1.00) and 82.2% (60/73; 95% CI: 0.72-0.90), respectively. No ME (false-resistant results) and VME (false-susceptible results) were detected. Kit showed acceptable CA, ME, and VME error parameters, whereas the EA did not meet the ≥90% threshold. Laboratories must check for possible limitations of commercial kits before they can be used for colistin susceptibility testing.

The impact of agar depth on antimicrobial susceptibility testing by disc diffusion.

Introduction. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) specifies the agar depth (4±0.5 mm) when performing antimicrobial susceptibility testing (AST). Since the infrastructure to produce standardized agar may be lacking in settings with limited resources, we wanted to examine to what extent variation in agar depth affects the inhibition zone diameters of quality control (QC) strains and AST of clinical isolates.Methods. The inhibition zone diameters on Mueller-Hinton II agar with different depths (2-6 mm) were tested for various QC strain-antimicrobial agent combinations using Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213. The relationship between zone diameters at different agar depths and MICs was investigated for 35 clinical isolates (E. coli, Klebsiella pneumoniae, S. aureus and P. aeruginosa) from Sierra Leone using MICs as the reference.Results. The inhibition zone diameters were within the acceptance ranges as defined by the EUCAST for the majority of QC strains and antimicrobials, independent of the agar depth. At extreme agar depths, inhibition zones were more frequently out of range. The accuracy of AST varied for clinical isolates at different agar depths for categorical agreement (85.8-94.6%), major error rate (0.4-2.1%) and very major error rate (VME: 3.3-12.5%).Conclusions. Even if the QC strains were in the acceptance range at different agar depths, this does not rule out unacceptably high VME rates (>3%) in clinical isolates.

Detection of mecA-mediated methicillin resistance and evaluation of disk-diffusion antimicrobial susceptibility characteristics of Staphylococcus saprophyticus isolates from geographically diverse locations: Staphylococcus saprophyticus antibiotic susceptibility testing

Staphylococcus saprophyticus, a common uropathogen, is usually susceptible to urine-concentrating antimicrobials, so routine AST is not recommended by CLSI. Our study evaluated the antimicrobial resistance profiles of 277 S. saprophyticus isolates from North America and a globally diverse cohort. Notably, 24% (67/277) of our isolates come from non-urinary sources. AST was performed against 12 antimicrobials using standard disk diffusion, PCR for mecA and mecC, PBP2a production assays, and cefinase. 5% (13/277) of isolates were mecA positive and cefinase positive, 63% (176/277) were mecA negative but cefinase positive, 4% (11/277) were mecA positive but cefinase negative, and 28% (77/277) were mecA and cefinase negative. All (277/277) isolates were susceptible to delafloxacin, ciprofloxacin, rifampin, linezolid, and nitrofurantoin and 95% (262/277) were susceptible to trimethoprim-sulfamethoxazole. Our results showed that regardless of using CLSI or EUCAST breakpoints oxacillin had low categorical agreement for mecA presence, making it unsuitable for surrogate testing, while cefoxitin disk diffusion had high very major error rate. If possible, PBP2a or mecA testing is recommended for guiding therapy for non-urinary infections. Our work supports CLSI guidelines on routine susceptibility to urinary tract antibiotics.

Evaluation of several routine methods for fosfomycin and mecillinam susceptibility testing of Enterobacterales urine isolates.

Performance evaluation of routine laboratory methods to determine the susceptibility of Enterobacterales urinary isolates to fosfomycin (oral administration) and mecillinam. We collected 347 Enterobacterales isolates from monomicrobial midstream urine samples from women with significant bacteriuria and leukocyturia. Mostly non-Escherichia coli isolates (i.e. Klebsiella spp., Citrobacter koseri, Enterobacter cloacae complex and Proteus mirabilis) were included (n = 298). Performance of VITEK®2, ETEST®, and disc diffusion to determine fosfomycin and mecillinam susceptibility was evaluated following International Organization for Standardization (ISO) 20776-2:2021 (or 20776-2:2007 for disc diffusion) in comparison with the agar dilution reference method. For fosfomycin testing, VITEK®2 and ETEST® were close to reaching ISO requirements (essential agreement ≥ 90%; bias ±30%) for C. koseri, E. coli and P. mirabilis. Categorical agreement (CA) and major error rates were acceptable for disc diffusion. Fosfomycin displayed lower activity against E. cloacae complex and Klebsiella spp., with MIC50 (minimum inhibitory concentration required to inhibit the growth of 50% of tested isolates) equal to the E. coli EUCAST breakpoint (8 mg/L). For these species, the three alternative techniques overestimated MICs and resistance, and did not meet performance criteria. For mecillinam testing of Enterobacterales isolates, apart from P. mirabilis, ETEST® nearly fulfilled ISO requirements, and CA rates were acceptable for disc diffusion. ISO criteria were reached for C. koseri and E. coli testing with VITEK®2, apart from too high rates of very major errors. For P. mirabilis, performances were unacceptable, whatever the routine method used. Commercially available tests may serve as alternatives to agar dilution to assess fosfomycin (oral) and mecillinam susceptibility of Enterobacterales urinary isolates, with important interspecies variabilities. Additional studies comprising more fosfomycin- and mecillinam-resistant isolates are needed to strengthen our conclusions.

Evaluation of Direct Antimicrobial Susceptibility Testing of Gram-Negative Bacilli and Staphylococcus aureus from Positive Pediatric Blood Culture Bottles Using BD Phoenix M50.

Bloodstream infections (BSIs) are life-threatening infections for which a timely initiation of appropriate antimicrobial therapy is critical. Antibiotic susceptibility testing (AST) directly performed on positive blood culture broths can help initiate targeted antibiotic therapy sooner than the standard AST performed on colonies isolated on solid media after overnight incubation. Faster antimicrobial susceptibility testing (AST) results can improve clinical outcomes, and reduce broad-spectrum antimicrobial consumption and healthcare-associated costs in sepsis. In this study, we evaluated the accuracy of a direct AST inoculation method on the BD Phoenix M50 system using serum separator tubes to harvest bacteria from positive pediatric blood culture bottles. Direct AST was performed on 132 monomicrobial pediatric blood culture bottles that were positive for Enterobacterales (65; 49.2%), Staphylococcus aureus (46; 34.8%), and non-fermenting Gram-negative bacilli (21; 16%). Overall, the categorical and essential agreements between the direct method and standard method were 99.6% and 99.8%, respectively. Very major, major, and minor error rates were 0.1%, 0.09%, and 0.20% respectively. Direct AST performed on pediatric blood culture bottles using BD Phoenix M50 can quickly provide accurate susceptibility information to guide antimicrobial therapy in patients with BSI.

Evaluation of gradient diffusion in vitro susceptibility testing of Aerococcus urinae

ObjectiveAerococcus urinae antimicrobial susceptibility testing can be performed via broth microdilution with Mueller-Hinton broth supplemented with lysed horse blood. We sought to compare this with the commonly used gradient diffusion method. MethodsWe compared broth microdilution with Mueller-Hinton broth supplemented with lysed horse blood and gradient diffusion via Mueller-Hinton agar supplemented with sheep blood for 190 A. urinae isolates against 16 antimicrobials. ResultsNo antimicrobials demonstrated more than 90% essential and categorical agreement, and fewer than 3% demonstrated major and very major error rates. Trimethoprim-sulfamethoxazole demonstrated an 81% major error rate and ceftriaxone demonstrated a 76% very major error rate. Agar dilution with lysed horse blood was performed for trimethoprim-sulfamethoxazole against 94 isolates and showed 100% susceptibility, consistent with previous studies. ConclusionsGiven its limitations in detecting resistant strains, our findings cannot support the routine use of gradient diffusion with Mueller-Hinton agar supplemented with sheep blood for A. urinae in lieu of the Clinical and Laboratory Standards Institute method. Our results suggest that A. urinae is usually susceptible to penicillin, linezolid, tetracycline, and vancomycin. Future studies should evaluate alternative testing methods for clinical microbiology laboratories.

Comparative Evaluation of Colistin-Susceptibility Testing in Carbapenem-Resistant Klebsiella pneumoniae Using VITEK, Colistin Broth Disc Elution, and Colistin Broth Microdilution.

The study aimed to compare the results of colistin-susceptibility testing performed using the automated VITEK system, colistin broth microdilution (BMD), and colistin broth disk elution (CBDE) methods. This exploratory study was conducted in a tertiary care center in South India. Carbapenem-resistant Klebsiella pneumoniae (n = 49) isolates collected from a clinical microbiology laboratory over six months (March-September 2023) were used for the study. Among the 49 carbapenem-resistant Klebsiella pneumoniae isolates, 42 were found to be susceptible to carbapenem by all three methods. Seven isolates were found to be resistant to colistin using BMD and CBDE methods. Two isolates were incorrectly detected as colistin-susceptible, and one isolate was wrongly categorized as colistin-resistant using the automated VITEK system. CBDE is a reliable and cost-effective method that can be adopted in the routine microbiology laboratory for colistin-susceptibility testing, as it does not require any specialized equipment or techniques and is 100% consistent with the gold standard BMD method. Although the automated VITEK system is used in most routine microbiological laboratories for antibiotic-susceptibility testing, it cannot be reliably used for colistin-susceptibility testing due to its high error rates (very major error rate of 28.5%; major error rate of 2.4%).

Suboptimal bioinformatic predictions of antimicrobial resistance from whole-genome sequences in multidrug-resistant Corynebacterium isolates

Herein, we combined different bioinformatics tools and databases (BV-BRC, ResFinder, RAST, and KmerResistance) to perform a prediction of antimicrobial resistance (AMR) in the genomic sequences of 107 Corynebacterium striatum isolates for which trustable antimicrobial susceptibility (AST) phenotypes could be retrieved. Then, the reliabilities of the AMR predictions were evaluated by different metrics: area under the ROC curve (AUC); Major Error Rates (MERs) and Very Major Error Rates (VMERs); Matthews Correlation Coefficient (MCC); F1-Score; and Accuracy. Out of 15 genes that were reliably detected in the C. striatum isolates, only tetW yielded predictive values for tetracycline resistance that were acceptable considering Food and Drug Administration (FDA)'s criteria for quality (MER < 3.0% and VMER with a 95% C.I. ≤1.5-≤7.5); this was accompanied by a MCC score higher than 0.9 for this gene. Noteworthy, our results indicate that other commonly used metrics (AUC, F1-score, and Accuracy) may render overoptimistic evaluations of AMR-prediction reliabilities on imbalanced datasets. Accordingly, out of 10 genes tested by PCR on additional multidrug-resistant Corynebacterium spp. isolates (n = 18), the tetW gene rendered the best agreement values with AST profiles (94.11%). Overall, our results indicate that genome-based AMR prediction can still be challenging for MDR clinical isolates of emerging Corynebacterium spp.

Anatomical and physiological diagnostic discrepancies in fetuses with single-ventricle congenital heart disease in a contemporary cohort.

Image quality of fetal echocardiography (FE) has improved in the recent era, but few recent studies have reported the accuracy of FE, specifically in single ventricle (SV) congenital heart disease (CHD). This study aimed to assess the ability of FE to correctly predict SV-CHD postnatal anatomy and physiology in a contemporary cohort. The contemporary clinical reports of patients with SV-CHD, in which FE was performed between July 2017 and July 2021, were compared with postnatal echocardiograms from a formal quality assurance program. SV fetuses were grouped by anatomical subtype. Diagnostic errors were designated as major if the error would have caused significant alteration in parental counseling or postnatal management. The remaining errors were classified as minor. Physiological discrepancies, including prostaglandin-E (PGE) dependency, atrioventricular valve regurgitation (AVVR), pulmonary venous obstruction, and restrictive atrial septum (RAS) were assessed by chart review of the postnatal course. A total of 119 subjects were analyzed. SV subtypes in the cohort included hypoplastic left heart syndrome (HLHS) (n = 68), tricuspid atresia (n = 16), double-inlet left ventricle (n = 12), unbalanced atrioventricular canal (UAVC) (n = 11), heterotaxy (n = 9) and other (n = 3). The rate of major anatomical and physiological errors was low (n = 6 (5.0%)). A higher proportion of minor errors was noted in HLHS and tricuspid atresia, but the differences were not statistically significant. Physiological discrepancies were uncommon, with three major discrepancies, including underestimation of the degree of venous obstruction in one non-HLHS fetus with total anomalous pulmonary venous return, overestimation of RAS in one HLHS fetus and incorrect prediction of PGE dependency in one case false-negative for pulmonary blood flow. No discrepancy in degree of AVVR or RAS affected postnatal care. Minor physiological discrepancies included two false-positive predictions of PGE dependency with one false-positive for ductal-dependent systemic flow and one false-positive for pulmonary blood flow. In this contemporary review of FE at our center, there was high accuracy in describing anatomical and physiological findings in SV-CHD. Major physiological discrepancies were uncommon but included important cases of false-negative prediction of PGE dependency and underestimation of obstruction of total anomalous pulmonary venous return. These data can inform more accurate counseling of families with SV-CHD fetuses and guide diagnostic improvement efforts. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Evaluation of Automated Disk Diffusion Antimicrobial Susceptibility Testing Using Radian® In-Line Carousel

Antimicrobial susceptibility testing (AST) by disk diffusion provides an accurate image of bacterial growth, enabling the detection of culture purity, heterogeneous growth, and antibiotic interactions. However, this manual method is time-consuming and visual interpretation is prone to errors. To overcome these disadvantages, the Radian® In-Line Carousel (Copan, Brescia, Italy) was launched, which is a WASPLab® module dedicated to full automation of (pre)-analytical steps as well as interpretation of disk diffusion AST. However, until now, no evaluation of Radian® against manual disk diffusion has been performed. We assessed the categorical agreement (CA) between standardized disk diffusion (reference method) and Radian® using EUCAST 2021 breakpoints. We tested 135 non-duplicate strains, selected from the National EUCAST challenge panel, clinical strains, and external quality controls. The strains included Enterobacterales (n = 63), Enterococcus faecalis (n = 3), Enterococcus faecium (n = 10), Pseudomonas aeruginosa (n = 16), Staphylococcus aureus (n = 19), coagulase-negative staphylococci (n = 4), and Streptococcus spp. (n = 20). Furthermore, we explored antibiotic disk thermolability in the WASP Radian® carousel by testing 10 ATCC® strains up to 7 days. The observed CA was 95.3%, 96.3%, 93.8%, 97.3% and 98.0% for Enterobacterales, Enterococcus spp., P. aeruginosa, Staphylococcus spp. and Streptococcus spp., respectively, resulting in an acceptable overall CA for all groups. (Very) major error rates were ≤ 5% for all antibiotics. Antibiotic disk thermostability was confirmed up to 4 days in the WASP Radian® In-Line Carousel. The Radian® In-Line Carousel provides a fully automated solution for accurate disk diffusion AST, reducing workload and improving standardization and traceability. In addition, our study demonstrated the thermostability of antibiotic disks up to 4 days in the WASP Radian® In-Line Carousel.

Comparison of Colistin Susceptibility Tests

Introduction: Polymyxins are important antimicrobial agents for the treatment of infections caused by Gram-negative bacteria. The susceptibility testing for polymyxins is a challenge for clinical laboratories due to the difficulty of performance, reproducibility, and accuracy of available methods. Aim: To compare the performance of the colistin susceptibility test of an automated system and a gradient test with the gold standard broth microdilution method (BMD). Materials and Methods: Multidrug-resistant isolates of Acinetobacter baumannii (n=102), Klebsiella pneumoniae (n=40), and Pseudomonas aeruginosa(n=11) were included. The VITEK 2 systems and gradient test were studied according to the manufacturer’s instructions. Broth microdilution tests were performed according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Commercial susceptibility testing methods were compared to BMD. Results: Rates of essential agreement of colistin test results between BMD, VITEK 2, and gradient test were 96.1% and 79.7%, respectively. The VITEK 2 and gradient test showed 95.4% and 94.8% of categorial agreement. The very major error rate of VITEK 2 was 3.2%, and the gradient test was 5.2%. The major error rate of VITEK 2 was 1.3%, and there was no major error for the gradient test. Conclusion and Suggestions: The very major error rate was higher in the gradient test (5.2%) than VITEK 2 (3.2%). Even if the very major error rate of VITEK 2 was lower, both resistance and susceptility results of VITEK 2 should be confirmed with the BMD test. Further studies for susceptibility testing are needed with a focus on the correlation of MIC’s results of different tests.

Comparison of carbapenem MIC for NDM-producing Enterobacterales by different AST methods.

This study compared the performance of MIC test strip (ETEST), automated AST card (Vitek 2) and broth microdilution (BMD) in determining carbapenem susceptibility and MIC values of NDM-producing Enterobacterales. NDM-producing Enterobacterales recovered from clinical specimens were included. The presence of blaNDM was confirmed by PCR. Identification of bacterial isolates was done by MALDI-TOF. Phenotypic susceptibility to three carbapenems (ertapenem, imipenem and meropenem) was tested by BMD, ETEST and Vitek 2. MIC values were interpreted in accordance with CLSI M100 (2022 edition). Using BMD as the reference standard, the essential agreement (EA), categorical agreement (CA), very major error (VME) and major error (ME) rates were evaluated. Forty-seven NDM-producing Enterobacterales isolates were included, 44 of which were Escherichia coli. The EA of Vitek 2 was 97.9% for ertapenem, 25.5% for meropenem and 42.6% for imipenem. Using Vitek 2, there were 0% VMEs across all three carbapenems tested. The EA of ETEST was 53.2% for ertapenem, 55.3% for imipenem and 36.2% for meropenem. The rates of VMEs for ETEST were high too (ertapenem 8.5%, meropenem 36.2%, imipenem 26.1%). The MIC values obtained from Vitek 2 were consistently higher than those from BMD, while MICs from ETEST were consistently lower than those from BMD. The VME rate for ETEST was unacceptably high when BMD was used as the standard for comparison. Vitek 2 had acceptable EA and CA for ertapenem when BMD was used as the standard for comparison. For meropenem and imipenem, neither of the methods (ETEST, Vitek 2) showed acceptable EA and CA when compared with BMD.

Establishment and Evaluation of a Resazurin-Based Microdilution Assay for Microbial Sensitivity Test of Neisseria gonorrhoeae

To establish and evaluate a microbial sensitivity test method for Neisseria gonorrhoeae based on resazurin coloration. Based on the broth microdilution method, resazurin was added as a live bacteria indicator. WHO G, a WHO gonococcal reference strain, was used to optimize the incubation time for resazurin-stained bacteria and the color change was visually observed to obtain the results. Agar dilution method (the gold standard) and resazurin-based microdilution assay were used to determine the minimum inhibitory concentration (MIC) of azithromycin, ceftriaxone, and spectinomycin for 3 reference strains and 32 isolates of Neisseria gonorrhoeae. The results were analyzed based on essential agreement (EA), which reflected the consistency of the MIC values, category agreement (CA), which reflected the consistency in the determination of drug resistance, intermediary, and sensitivity, very major error (VME), which reflected false sensitivity, and major error (ME), which reflected pseudo drug resistance, to evaluate the accuracy of resazurin-based microdilution assay as a microbial sensitivity test of of Neisseria gonorrhoeae. CA and EA rates≥90% and VME and ME rates≤3% were found to be the acceptable performance rates. The results obtained 6 hours after resazurin was added were consistent with those of the agar dilution method and the resazurin-based microdilution assay was established accordingly based on this parameter. The EA of resazurin-based microdilution assay for measuring the MIC results of azithromycin, ceftriaxone, and spectinomycin was 97.1%, 91.5%, and 94.3%, respectively, and the CA was 88.6%, 94.3%, and 94.3%, respectively. The VME was 0% for all three antibiotics, while the ME was 11.4%, 5.7%, and 5.7%, respectively. The resazurin-based microdilution assay established in this study showed good agreement with agar dilution method for measuring the MIC of antibiotics against Neisseria gonorrhoeae. Moreover, the sensitivity results of this method were highly reliable and could be easily obtained through naked eye observation. Nonetheless, the results of drug resistance should be treated with caution and the optimization of parameters should be continued.

Machine learning and feature extraction for rapid antimicrobial resistance prediction of Acinetobacter baumannii from whole-genome sequencing data.

Whole-genome sequencing (WGS) has contributed significantly to advancements in machine learning methods for predicting antimicrobial resistance (AMR). However, the comparisons of different methods for AMR prediction without requiring prior knowledge of resistance remains to be conducted. We aimed to predict the minimum inhibitory concentrations (MICs) of 13 antimicrobial agents against Acinetobacter baumannii using three machine learning algorithms (random forest, support vector machine, and XGBoost) combined with k-mer features extracted from WGS data. A cohort of 339 isolates was used for model construction. The average essential agreement and category agreement of the best models exceeded 90.90% (95%CI, 89.03-92.77%) and 95.29% (95%CI, 94.91-95.67%), respectively; the exceptions being levofloxacin, minocycline and imipenem. The very major error rates ranged from 0.0 to 5.71%. We applied feature selection pipelines to extract the top-ranked 11-mers to optimise training time and computing resources. This approach slightly improved the prediction performance and enabled us to obtain prediction results within 10 min. Notably, when employing these top-ranked 11-mers in an independent test dataset (120 isolates), we achieved an average accuracy of 0.96. Our study is the first to demonstrate that AMR prediction for A. baumannii using machine learning methods based on k-mer features has competitive performance over traditional workflows; hence, sequence-based AMR prediction and its application could be further promoted. The k-mer-based workflow developed in this study demonstrated high recall/sensitivity and specificity, making it a dependable tool for MIC prediction in clinical settings.

A-273 Multicenter Assessment of the Accuracy of MIC Results for Piperacillin/Tazobactam with MicroScan Dried Gram-Negative MIC Panels using CLSI Breakpoints

Abstract Background MIC data from MicroScan Dried Gram-negative MIC (MSDGN) Panels with piperacillin/tazobactam were evaluated with CLSI-M100-ED32 breakpoints for Acinetobacter, Enterobacterales, Other-Non-Enterobacterales, and proposed CLSI breakpoints for Pseudomonas aeruginosa from a multicenter clinical study. MIC results were compared to results obtained with CLSI frozen broth microdilution panels. Materials/Methods The study included a total of 683 clinical isolates tested using Prompt and turbidity during efficacy and challenge phases. MSDGN panels were evaluated at three clinical sites, comparing MIC values obtained using MSDGN panels to MICs utilizing CLSI reference panel. MSDGN panels were incubated at 35 ± 1°C and read on WalkAway System, autoSCAN-4 instrument, and read visually at 16–20 h. Frozen reference panels were prepared according to CLSI methodology, incubated for 16–20 h for Enterobacterales, Other Non-Enterobacterales, and Pseudomonas aeruginosa and for 20–24 h for Acinetobacter and read visually. CLSI breakpoints(mg/L) used for interpretation of MIC results were: ≤16/4 S, 32/4–64/4 I, ≥128/4 R for Acinetobacter and Other Non Enterobacterales, ≤8/4 S, 16/4 SDD, ≥32/4 R for Enterobacterales, and ≤16/4 S, 32/4 I, &amp;gt;64/4 R for Pseudomonas aeruginosa. Results When compared to frozen reference panel results, essential and categorical agreements for all isolates tested are as follows with these recommendations: Due to elevated major error rates for S. marcescens and WalkAway reads with Prompt, results should be confirmed visually prior to reporting. Due to performance with P. rettgeri and S. liquefaciens complex, do not report drug, therapy, or MIC. Conclusion Piperacillin/tazobactam MIC results for gram-negative clinical isolates obtained with the MSDGN panel correlate with MICs obtained using frozen reference panels with updated CLSI interpretive criteria.

Rapid Identification and Antimicrobial Susceptibility Testing of Gram Positive Bacteria by Direct Inoculation from Positive Blood Culture Bottles

Abstract Background Rapid identification of the causative agent for sepsis and determination of its susceptibility profile by direct inoculation of the biochemical and susceptibility testing media with the blood-broth mixtures from signal positive bottles might help reducing the time needed for provision of results compared to the standard isolated-colony based method and hence would help the rapid initiation of effective and targeted antimicrobial therapy and reduce the bacteremia-related morbidity and mortality Aim of the Work To validate the direct inoculation method as a rapid method for the identification of Gram-positive bacteremic isolates and determination of their antimicrobial susceptibility profile by comparing its results to that of the standard isolate-based method routinely used in our laboratories. Patients and Methods This study included a total of 100 positive blood culture bottles submitted to the Main Microbiology laboratory for identification and antimicrobial susceptibility testing via disk diffusion method directly from blood culture bottles and according to standard isolate-based identification method. Results There was a 100% categorical agreement between the results of the direct (primary) biochemical identification method and those of the standard isolate-based identification method. As regard AST the overall categorical agreement between both methods was 96.9%, the minor error rate was 0.8% and the major error rate was 2.3%. Conclusion Rapid Identification and Antimicrobial Susceptibility Testing of Gram-positive Bacteria is a time saving method and can help in reducing turnaround time to obtain AST results.

A prospective study evaluating the effect of a ‘Diagnostic Stewardship Care-Bundle’ for automated blood culture diagnostics

We prospectively implemented a diagnostic stewardship care-bundle checklist, 'Sepsis-48 DSB', with the aim of reducing intervening duration of key steps of automated blood culture diagnostics (aBCD). Sepsis-48 DSB was implemented for automated blood culture bottles (BCBs) received from adult intensive care units (AICUs) during the intervention period (P2; July 2020-June 2021) and intervening durations were compared with those during the retrospective, pre-intervention period (P1; March-June 2020). During both periods, provisional blood culture reports (pBCR) were issued wherein direct microbial identification (dID) was performed in BCBs with Gram-negatives by directly inoculating conventional biochemical tests and direct antimicrobial susceptibility testing (dAST) using EUCAST RAST method. The results were compared with the standard of care (SoC) method (i.e. full incubation followed by identification and AST by VITEKⓇ-2 Compact). During P2, significant reductions in loading time (LT) [median: 63.5 vs. 32 minutes, P < 0.001], time to dID+dAST performance (TTD) [186 vs. 115 minutes, P=0.0018] and an increase in compliance to bundle targets [LT ≤45: 44% vs. 66%, P=0.006 and TTD ≤120: 34% vs. 51.7%, P=0.03] were observed. Using dID+dAST method, results were read 694 minutes earlier than SoC method. Of 176 pBCR, 165 (94%) were concordant with SoC in microbial identification of species. Categorical agreement for any drug-bug combination was 92.7% (1079/1164) and corresponding major, very major, and minor error rates were 8.8% (19/216), 4.9% (45/921), and 1.8% (21/1164), respectively. The 'diagnostic stewardship care-bundle' strategy was successfully implemented with considerable diagnostic accuracy leading to significant reductions in duration of targeted steps of aBCD.

Performance Evaluation of BD Phoenix and MicroScan WalkAway Plus for Determination of Fosfomycin Susceptibility in Enterobacterales.

Fosfomycin is an old bactericidal drug that has gained increasing interest in the last decade for its potential use in multi-drug resistant gram-negative infections. However, evidence on fosfomycin susceptibility testing reports a poor correlation between commercial methods vs. reference agar dilution (AD) for Enterobacterales (EB). The study aimed at assessing the performance of two automated systems for the determination of fosfomycin susceptibility in EB clinical isolates. Fosfomycin susceptibility testing results of two collections of 100 non-duplicate clinical EB strains obtained using two different platforms (BD Phoenix and MicroScan WalkAway Plus) were compared with those obtained by AD. Categorical agreement (CA), major error (ME) and very major error (VME) rates were calculated. BD Phoenix exhibited a 6.9% rate of false-resistant results and achieved a CA of 69%, whereas MicroScan WalkAway Plus achieved 3.7% of false-resistant results and 72% of CA. Both automated systems showed poor detection of resistant isolates, with 49.1% and 56.2% of false-susceptible results for BD Phoenix and Microscan WalkAway Plus, respectively. Overall, agar dilution remains the most suitable method for routine laboratory antimicrobial susceptibility testing of fosfomycin on Enterobacterales strains, given the poor performance of automated systems. The application of both automated systems, in the clinical laboratories reporting of fosfomycin, should be reviewed in light of the accuracy results falling below the acceptable threshold.

Reference accuracy of primary studies published in peer-reviewed scholarly journals: A scoping review

Objective. The objective of this scoping review was to identify key characteristics of primary research studies in peer-reviewed journals about reference accuracy. Characteristics of studies include the publication year, field of study, journal name and publication year of verified references, number of references verified, reference elements examined, definition of major, intermediate, and minor errors, whether punctuation or typographical errors were counted, overall error rate, major, intermediate, and minor error rates, and most common error type. Introduction. Reference accuracy has been studied across several decades and remains a persistent issue in peer-reviewed publications. Reference accuracy is typically reported as an error rate that represents the proportion of references with at least one error. Inclusion criteria for this scoping review included primary studies published in peer-reviewed journals that verified references in articles. Methods. Library, Information Science and Technology Abstracts (LISTA), Medline via EBSCOhost, and Web of Science were searched with final searches conducted in all three databases on November 26, 2022. No grey literature sources were searched given the focus of the project on peer-reviewed scholarly journals. Results. A total of 105 studies were included. The overall error rate across all studies was 32.7%. The error rates within specific fields of study were relatively similar. There is a lack of clarity about whether studies counted punctuation or typographical errors. The most common error was related to author names. Conclusions. There is a lack of studies to understand the most effective means to increase reference accuracy that are feasible to implement on a wide scale. Future research is warranted to understand how best to improve reference accuracy across fields of study.