scholarly journals Multicenter Clinical Evaluation of Etest Meropenem-Vaborbactam (bioMérieux) for Susceptibility Testing of Enterobacterales (Enterobacteriaceae) and Pseudomonas aeruginosa

2019 ◽  
Vol 58 (1) ◽  
Author(s):  
Sophonie Jean ◽  
Sheri Garrett ◽  
Claire Anglade ◽  
Laurence Bridon ◽  
Leanne Davies ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Individual Species ◽  
Beta Lactamase ◽  
Content Type ◽  
European Committee ◽  
Tract Infections ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACT Meropenem-vaborbactam (MEV) is a novel carbapenem–beta-lactamase inhibitor combination antibiotic approved by the U.S. Food and Drug Administration (FDA) for treatment of complicated urinary tract infections, including pyelonephritis, in adults. In this study, we evaluated the performance of Etest MEV (bioMérieux, Marcy l’Etoile, France) compared to that of broth microdilution for 629 Enterobacterales and 163 Pseudomonas aeruginosa isolates. According to CLSI/FDA breakpoints, 13 Enterobacterales isolates (12 clinical and 1 challenge) were resistant to MEV. Overall, Etest MEV demonstrated 92.4% essential agreement (EA), 99.2% category agreement (CA), 0% very major errors (VME), 0% major errors (ME), and 0.8% minor errors (mE) with clinical and challenge isolates of Enterobacterales. Individual species demonstrated EA rates of ≥80%, with the exception of Proteus mirabilis, for which clinical and challenge isolates demonstrated 34.3% EA, 97.1% CA, 0% ME, and 2.9% mE, precluding the use of Etest MEV with this species. Excluding P. mirabilis, MEV Etest MEV demonstrated 95.8% EA, 99.3% CA, 0% VME, 0% ME, and 0.7% mE with Enterobacterales isolates. When evaluated using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, Etest MEV performance with clinical (16 MEV resistant) and challenge (12 MEV resistant) isolates of Enterobacterales (excluding P. mirabilis) and P. aeruginosa demonstrated an unacceptably high VME rate of 7.1% despite 95.2% EA, 99.2% CA, and 0.5% ME compared to the reference method. In conclusion, we report that Etest MEV is accurate and reproducible for MEV susceptibility testing for P. aeruginosa and Enterobacterales, with the exception of P. mirabilis, using CLSI/FDA breakpoints. Etest MEV should not be used with P. mirabilis due to unacceptable analytical performance.

scholarly journals Multicenter Evaluation of the Etest Gradient Diffusion Method for Ceftolozane-Tazobactam Susceptibility Testing of Enterobacteriaceae and Pseudomonas aeruginosa

2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Adam L. Bailey ◽  
Tom Armstrong ◽  
Hari-Prakash Dwivedi ◽  
Gerald A. Denys ◽  
Janet Hindler ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Beta Lactam ◽  
Content Type ◽  
Gradient Diffusion ◽  
Tract Infections ◽  
Abdominal Infections ◽  
Inhibitor Combination

ABSTRACT Ceftolozane-tazobactam (C/T) is a novel beta-lactam–beta-lactamase inhibitor combination antibiotic approved by the U.S. Food and Drug Administration in 2014 for the treatment of complicated intra-abdominal infections (in combination with metronidazole) and complicated urinary tract infections. In this study, we evaluated the performance of the C/T Etest, a gradient diffusion method. C/T Etest was compared to broth microdilution (BMD) for 51 Enterobacteriaceae challenge isolates and 39 Pseudomonas aeruginosa challenge isolates at three clinical sites. Essential agreement (EA) between the methods ranged from 47 to 49/51 (92.2 to 96.1%) for the Enterobacteriaceae, and categorical agreement (CA) ranged from 49 to 51/51 (96.1 to 100.0%). EA and CA for P. aeruginosa were 100% at all sites. The C/T Etest was also compared to BMD for susceptibility testing on 966 clinical isolates (793 Enterobacteriaceae, including 167 Klebsiella pneumoniae and 159 Escherichia coli isolates, in addition to 173 P. aeruginosa isolates) collected at four clinical sites. EA between Etest and BMD was 96.9% for Enterobacteriaceae isolates and 98.8% for P. aeruginosa isolates. Within the Enterobacteriaceae, isolates from each species examined had >96% CA. For the clinical isolates, no very major errors were identified but two major errors were found (one for K. pneumoniae and one for Providencia rettgeri). By BMD, 47.0% of Enterobacteriaceae and 46.2% of P. aeruginosa challenge strains were nonsusceptible to C/T by CLSI breakpoint criteria; 8.2% of clinical Enterobacteriaceae isolates and 12.1% of clinical P. aeruginosa isolates were nonsusceptible to C/T by CLSI breakpoint criteria. In conclusion, Etest is accurate and reproducible for C/T susceptibility testing of Enterobacteriaceae and P. aeruginosa.

Multicenter clinical evaluation of VITEK® 2 meropenem-vaborbactam for susceptibility testing of Enterobacterales and Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Hari P. Dwivedi ◽  
Simone Franklin ◽  
Sukantha Chandrasekaran ◽  
Omai Garner ◽  
Maria M. Traczewski ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Automated System ◽  
Individual Species ◽  
Method Performance ◽  
Overall Performance ◽  
Vitek 2 ◽  
Tract Infections ◽  
Alternate Solution ◽  
After Error

The carbapenem/beta-lactamase inhibitor (meropenem-vaborbactam; MEV) used to treat complicated urinary tract infections and pyelonephritis in adults was approved in 2017 by the U.S. Food and Drug Administration (FDA). We evaluated VITEK 2 MEV (bioMérieux, Durham, NC) compared to the reference broth microdilution (BMD) method. Of 449 Enterobacterales isolates analyzed per FDA/CLSI breakpoints, overall performance was 98.2% Essential Agreement (EA), 98.7% Category Agreement (CA), and 0% Very Major Errors (VME) or Major Errors (ME). For FDA intended for use 438 Enterobacterales isolates, performance was 98.2% EA, 98.6% CA, and 0% VME or ME. Evaluable EA was 81.0% but with only 42 on-scale evaluable results. Individual species demonstrated EA and CA rates ≥ 90% without any VME or ME. When evaluated using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, overall VITEK 2 MEV performance for Enterobacterales and Pseudomonas aeruginosa demonstrated 97.3% EA, 99.2% CA, 2.3% VME, and 0.6% ME (after error resolution: 97.3% EA, 99.4% CA, 2.2% VME, and 0.4% ME) compared to the reference BMD method. Performance for P. aeruginosa included 92.2% EA, 97.4% CA, 0% VME, and 3.0% ME (after error resolution: 92.2% EA, 98.7% CA, 0% VME, and 1.5% ME). Performance for Enterobacterales included 98.2% EA, 99.6% CA, 3.0% VME, and 0.2% ME. Evaluable EA was 80.6% but due to only 67 evaluable results. These findings support VITEK 2 MEV as an accurate automated system for MEV susceptibility testing of Enterobacterales and P. aeruginosa and could be an alternate solution to the manual labor intensive reference BMD method.

Piperacillin/Tazobactam: A New Beta-Lactam/Beta-Lactamase Inhibitor Combination

1995 ◽  
Vol 29 (5) ◽  
pp. 501-514 ◽  
Author(s):  
Lori L Schoonover ◽  
Donna J Occhipinti ◽  
Keith A Rodvold ◽  
Larry H Danziger
Keyword(s):  
Antimicrobial Activity ◽  
Clinical Efficacy ◽  
Clinical Laboratory ◽  
National Committee ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
In Vitro Susceptibility ◽  
Tract Infections ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

Objective: To discuss the antimicrobial activity, pharmacokinetics, clinical efficacy, and adverse effect profile of piperacillin/tazobactam, a new beta-lactam/beta-lactamase inhibitor combination. Data Sources: Literature was identified by MEDLINE search of the medical literature, review of selected references, and data provided by the manufacturer. Study Selection: In vitro susceptibility data were surveyed from studies following the methods of the National Committee for Clinical Laboratory Standards. Data evaluating clinical efficacy were selected from all published trials and abstracts. Additional information concerning safety, chemistry, and pharmacokinetics was reviewed. Data Synthesis: The antimicrobial activity of piperacillin is enhanced by addition of tazobactam against gram-positive, gram-negative, and anaerobic bacteria. Tazobactam is active against a broad spectrum of plasmid and chromosomally mediated enzymes and has minimal ability to induce class I chromosomally mediated beta-lactamase enzymes. Piperacillin/tazobactam's expanded activity appears encouraging in the treatment of mixed aerobic and anaerobic infections. Direct comparisons of ticarcillin/clavulanate and piperacillin/tazobactam for the treatment of lower respiratory tract infections showed piperacillin/tazobactam to be clinically superior, and in the treatment of skin and soft tissue infections the 2 agents were comparable. For the treatment of intraabdominal infections, piperacillin/tazobactam was at least as effective as imipenem/cilastatin and clindamycin plus gentamicin. Conclusions: The combination of tazobactam with piperacillin results in an antimicrobial agent with enhanced activity against most beta-lactamase–producing organisms. Preliminary data indicate that piperacillin/tazobactam has proven clinical efficacy in the treatment of a variety of infections, especially polymicrobic infections.

scholarly journals Validation of Sensititre Dry-Form Broth Microdilution Panels for Susceptibility Testing of Ceftazidime-Avibactam, a Broad-Spectrum-β-Lactamase Inhibitor Combination

2015 ◽  
Vol 59 (8) ◽  
pp. 5036-5039 ◽  
Author(s):  
Ronald N. Jones ◽  
Nicole M. Holliday ◽  
Kevin M. Krause
Keyword(s):  
Broad Spectrum ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Broth Microdilution ◽  
Content Type ◽  
Serious Infections ◽  
Validation Experiment ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACTCeftazidime-avibactam is a broad-spectrum-β-lactamase inhibitor combination in late-stage clinical development for the treatment of serious infections. In preparation for clinical microbiology laboratory use, a validation experiment was initiated to evaluate a commercial broth microdilution product (Sensititre dried MIC susceptibility system) compared to reference panels using 525 recent clinical isolates. Among 11 pathogen groups, all had Sensititre MIC/reference MIC ratios predominantly at 1 (47.5% to 97.5%), and automated and manual endpoint results did not differ.EnterobacteriaceaeMIC comparisons showed a modest skewing of Sensititre MIC results toward an elevated MIC (33.9%), but the essential agreement was 98.9% with 100.0% reproducibility. In conclusion, Sensititre panels produced accurate ceftazidime-avibactam MIC results, allowing quality MIC guidance for therapy following regulatory approvals.

scholarly journals Pharmacokinetics/Pharmacodynamics of Vaborbactam, a Novel Beta-Lactamase Inhibitor, in Combination with Meropenem

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
David C. Griffith ◽  
Mojgan Sabet ◽  
Ziad Tarazi ◽  
Olga Lomovskaya ◽  
Michael N. Dudley
Keyword(s):  
Hollow Fiber ◽  
Infection Model ◽  
Beta Lactamase ◽  
Fiber Model ◽  
Content Type ◽  
Development Of Resistance ◽  
Wide Range ◽  
Tract Infections ◽  
Lactamase Inhibitor

ABSTRACT Vaborbactam is a novel beta-lactamase inhibitor with activity against important beta-lactamases, in particular, serine carbapenemases, and is currently approved in combination with meropenem as Vabomere for the treatment of complicated urinary tract infections, including pyelonephritis. This combination is highly active against Gram-negative pathogens, especially Klebsiella pneumoniae carbapenemase (KPC)-producing carbapenem-resistant Enterobacteriaceae. The objective of these studies was to evaluate vaborbactam pharmacokinetics (PK) and pharmacodynamics (PD) relationships for efficacy in a neutropenic mouse thigh infection model, as well as in an in vitro hollow-fiber infection model, in combination with a fixed exposure of meropenem using KPC-containing strains of Enterobacteriaceae. For both models, the meropenem dosage regimen was designed to simulate a 2-g dose administered every eight hours (q8h) by 3-h infusion. Vaborbactam dosage regimens were designed to produce a wide range of 24-h areas under the concentration-time curves (AUCs) in the thigh infection model. However, for the hollow-fiber model, the AUCs were limited to values of 192, 320, or 550 mg · h/liter. In both the animal and in vitro models, the PK-PD parameter that best described the antibacterial activity of vaborbactam, when administered in combination with meropenem at exposures equivalent to 2 g dosed q8h by 3-h infusion in humans, was the 24-h free vaborbactam AUC/meropenem-vaborbactam (with vaborbactam at 8 mg/liter) MIC ratio. The magnitude of this ratio for bacteriostasis was 9 to 12 and the magnitude to observe a 1-log kill was 18 to 38. In addition, a magnitude greater than 24 suppressed the development of resistance in the in vitro hollow-fiber model.

scholarly journals Mutation-Driven β-Lactam Resistance Mechanisms among Contemporary Ceftazidime-Nonsusceptible Pseudomonas aeruginosa Isolates from U.S. Hospitals

2014 ◽  
Vol 58 (11) ◽  
pp. 6844-6850 ◽  
Author(s):  
Mariana Castanheira ◽  
Janet C. Mills ◽  
David J. Farrell ◽  
Ronald N. Jones
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Strong Correlation ◽  
Efflux Pumps ◽  
Resistance Mechanisms ◽  
Content Type ◽  
Expression Levels ◽  
Elevated Expression ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACTOprD loss and hyperexpression of AmpC, MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY-OprM were evaluated among 120Pseudomonas aeruginosaisolates collected during 2012 in U.S. hospitals and selected based on ceftazidime MIC values (1 to >32 μg/ml). AmpC derepression (10-fold greater than that with the control) and OprD loss (decreased/no band) were the most prevalent resistance mechanisms: 47.5 and 45.8% of the isolates were considered positive, respectively. Elevated expression of the efflux pumps MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY-OprM was observed in 32.5, 8.3, 0.0, and 28.4% of the isolates, respectively. A total of 21 different combinations of resistance mechanisms were noted, and the most prevalent included AmpC derepression with OprD loss with and without efflux hyperexpression (38 and 10 isolates, respectively). A total of 26 isolates had no changes in the resistance mechanisms tested and had lower MIC values for all β-lactams or β-lactam/β-lactamase inhibitor combinations analyzed. OprD loss had a strong correlation with elevated MIC results for imipenem and meropenem (median MIC values of 8 and 4 μg/ml, respectively), with all combinations displaying OprD loss also displaying elevated median MIC values for these carbapenems (4 to >8 μg/ml). AmpC expression levels were greater in isolates displaying elevated cefepime, ceftazidime, or piperacillin-tazobactam MIC values (≥4, ≥4, and ≥16 μg/ml, respectively). Isolates displaying derepressed AmpC had ceftolozane-tazobactam MIC values ranging from 1 to 16 μg/ml. No strong correlation was noticed with MIC values for this β-lactam/β-lactamase inhibitor combination and OprD loss or hyperexpression of efflux systems. Two KPC-producing isolates were detected among 16 isolates displaying ceftolozane-tazobactam MIC values of ≥8 μg/ml.

scholarly journals Emergence of Ceftolozane-Tazobactam-Resistant Pseudomonas aeruginosa during Treatment Is Mediated by a Single AmpC Structural Mutation

2017 ◽  
Vol 61 (12) ◽  
Author(s):  
Shawn H. MacVane ◽  
Ruchi Pandey ◽  
Lisa L. Steed ◽  
Barry N. Kreiswirth ◽  
Liang Chen
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Wound Infection ◽  
Clinical Isolates ◽  
Content Type ◽  
Structural Mutation ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACT Ceftolozane-tazobactam is a cephalosporin-β-lactamase inhibitor combination that exhibits potent in vitro activity against Pseudomonas aeruginosa, including strains that are resistant to other β-lactams. The emergence of ceftolozane-tazobactam resistance among clinical isolates of P. aeruginosa has rarely been described. Here we characterized ceftolozane-tazobactam-resistant P. aeruginosa strains recovered from a patient who was treated with this agent for 6 weeks for a recurrent wound infection. The results showed that the resistance was mediated by a single AmpC structural mutation.

scholarly journals Impact of Intrinsic Resistance Mechanisms on Potency of QPX7728, a New Ultrabroad-Spectrum Beta-Lactamase Inhibitor of Serine and Metallo-Beta-Lactamases in Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Olga Lomovskaya ◽  
Kirk Nelson ◽  
Debora Rubio-Aparicio ◽  
Ruslan Tsivkovski ◽  
Dongxu Sun ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Resistance Mechanisms ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Intrinsic Resistance ◽  
Content Type ◽  
Beta Lactamases ◽  
Beta Lactam Antibiotics ◽  
Lactamase Inhibitor

ABSTRACT QPX7728 is an ultrabroad-spectrum boronic acid beta-lactamase inhibitor that demonstrates inhibition of key serine and metallo-beta-lactamases at a nanomolar concentration range in biochemical assays with purified enzymes. The broad-spectrum inhibitory activity of QPX7728 observed in biochemical experiments translates into enhancement of the potency of many beta-lactams against strains of target pathogens producing beta-lactamases. The impacts of bacterial efflux and permeability on inhibitory potency were determined using isogenic panels of KPC-3-producing isogenic strains of Klebsiella pneumoniae and Pseudomonas aeruginosa and OXA-23-producing strains of Acinetobacter baumannii with various combinations of efflux and porin mutations. QPX7728 was minimally affected by multidrug resistance efflux pumps either in Enterobacteriaceae or in nonfermenters, such as P. aeruginosa or A. baumannii. Against P. aeruginosa, the potency of QPX7728 was further enhanced when the outer membrane was permeabilized. The potency of QPX7728 against P. aeruginosa was not affected by inactivation of the carbapenem porin OprD. While changes in OmpK36 (but not OmpK35) reduced the potency of QPX7728 (8- to 16-fold), QPX7728 (4 μg/ml) nevertheless completely reversed the KPC-mediated meropenem resistance in strains with porin mutations, consistent with the lesser effect of these mutations on the potency of QPX7728 compared to that of other agents. The ultrabroad-spectrum beta-lactamase inhibition profile, combined with enhancement of the activity of multiple beta-lactam antibiotics with various sensitivities to the intrinsic resistance mechanisms of efflux and permeability, indicates that QPX7728 is a useful inhibitor for use with multiple beta-lactam antibiotics.

scholarly journals Antimicrobial Activity of Ceftolozane–Tazobactam Tested against Contemporary (2012–2016) Enterobacteriaceae and Pseudomonas aeruginosa Isolates by US Census Division

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S371-S372
Author(s):  
Dee Shortridge ◽  
Leonard R Duncan ◽  
Michael A Pfaller ◽  
Robert K Flamm
Keyword(s):  
Pseudomonas Aeruginosa ◽  
The United States ◽  
Gram Negative ◽  
Carbapenem Resistant ◽  
Tract Infections ◽  
Abdominal Infections ◽  
Us Census ◽  
Phenotype Screen ◽  
Lactamase Inhibitor ◽  
Research Grant

Abstract Background Ceftolozane-tazobactam (C-T) is a combination of a novel antipseudomonal cephalosporin and a well-described β-lactamase inhibitor. C-T was approved by the United States (US) Food and Drug Administration in 2014 for complicated urinary tract infections, including acute pyelonephritis and complicated intra-abdominal infections. C-T is currently in clinical trials for the treatment of nosocomial pneumonia. The Program to Assess Ceftolozane-Tazobactam Susceptibility (PACTS) monitors C-T resistance to gram-negative (GN) isolates worldwide. In this study, the activities of C-T and comparators vs. GN isolates from each of the 9 US Census divisions were compared. Methods A total of 18,856 Enterobacteriaceae (ENT) and 4,735 Pseudomonas aeruginosa (PSA) isolates were collected from 32 US hospitals in 2012–2016. Isolates were tested for susceptibility (S) to C-T and comparators by CLSI broth microdilution methodology in a central monitoring laboratory. Other antibiotics tested included amikacin (AMK), ceftazidime (CAZ), colistin (COL), meropenem (MER), and piperacillin-tazobactam (TZP). The following resistant phenotypes were analyzed for ENT: carbapenem resistant (CRE); extended-spectrum β-lactamase phenotype screen-positive (ESBL); and ESBL, nonCRE. or PSA, MER-nonsusceptible (NS), TZP-NS, and CAZ-NS isolates were analyzed. CLSI (2017) interpretive criteria were used. Results For all ENT, 94.2% were S to C-T, 91.5% were S to TZP, 98.0% were S to MER, and 98.8% were S to AMK; 1,697 (9.0%) were ESBL, nonCRE and 356 (1.9%) were CRE. For all PSA isolates, 97.4% were S to C-T, 99.3% were S to COL, 96.9% were S to AMK, and 81.2% were S to MER. The % C-T S for each division (DIV) are shown in the table. The % C-T S for ENT ranged from 98.1% (DIV 4) to 87.4% (DIV 2) and % C-T S for ESBL, nonCRE ranged from 93.8% in DIV 4 to 79.8% in DIV 7. For PSA, the % C-T S ranged from 99.6% in DIV 4 to 94.9% in DIV 9. Activity of C-T against PSA NS to MER, CAZ or TZP varied by division and was >80% for all except DIV 9. Conclusion Against PSA, only COL was more active than C-T. C-T demonstrated potent activity against PSA NS to other β-lactams. For ENT, overall activity was good. For both PSA and ENT, C-T varied by DIV. Disclosures D. Shortridge, Merck: Research Contractor, Research grant; L. R. Duncan, Merck: Research Contractor, Research grant; M. A. Pfaller, Merck: Research Contractor, Research grant; R. K. Flamm, Merck: Research Contractor, Research grant

scholarly journals Multicenter Evaluation of Ceftazidime-Avibactam Susceptibility Testing of Enterobacterales and Pseudomonas aeruginosa on the VITEK® 2 System

2020 ◽  
Author(s):  
Romney Humphries ◽  
Shelley Campeau ◽  
Thomas E. Davis ◽  
Kristin J. Nagaro ◽  
Vincent J. LaBombardi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Error Rate ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Error Rates ◽  
Performance Criteria ◽  
Test Results ◽  
Major Error ◽  
Overall Performance ◽  
Vitek 2

In this multisite study, VITEK® 2 AST-Gram-Negative Ceftazidime-Avibactam (CZA) test results for 1073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa) were compared to the Clinical & Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (S ≤8/4 μg/ml and R ≥16/4 μg/ml). The overall EA was 94.5% (1014/1073) and CA was 98.7% (1059/1073). No very major errors were reported. The major error rate was 1.4% (14/998). Out of 14 major errors, 9 were within EA. Based on the EA and lack of an intermediate category for CZA, the adjusted major error rate for FDA criteria was 0.5% (5/998). The performance for ISO criteria after error resolutions included EA 94.5% (1014/1073), CA 98.9% (1061/1073), major error 1.2% (12/998), and no very major error. Vitek 2 met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. Vitek 2 overall performance for Enterobacterales and P. aeruginosa met or exceeded the FDA and ISO performance criteria and thus is a reliable alternative to BMD reference method for routine CZA susceptibility testing.

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