Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates
Objective: Piperacillin/tazobactam antimicrobial susceptibility testing (AST) against Enterobacterales can be challenging. The aim of this study was to assess the reproducibility of various automated (VITEK 2) and nonautomated AST methods (broth microdilution (BMD), minimum inhibitory concentration...
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Elsevier
2025-03-01
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| Series: | Journal of Global Antimicrobial Resistance |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2213716525000050 |
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| author | Faruk Demirocak Diana Langerak Erlangga Yusuf |
| author_facet | Faruk Demirocak Diana Langerak Erlangga Yusuf |
| author_sort | Faruk Demirocak |
| collection | DOAJ |
| description | Objective: Piperacillin/tazobactam antimicrobial susceptibility testing (AST) against Enterobacterales can be challenging. The aim of this study was to assess the reproducibility of various automated (VITEK 2) and nonautomated AST methods (broth microdilution (BMD), minimum inhibitory concentration (MIC) test strip, and disk diffusion) for piperacillin/tazobactam in ‘challenging’ E. coli isolates. Methods: We performed 20 repeated ASTs for seven clinical E. coli isolates: Two resistant to piperacillin/tazobactam but susceptible to amoxicillin/clavulanic acid, four isolates with various β-lactamase coding genes (two blaTEM-1, one blaOXA-1, and one with plasmidal blaampC), and one isolate where VITEK 2 initially could not produce MIC measurements for piperacillin/tazobactam (i.e. no results generated). Results: Upon repetition, the same MIC as the mode value (i.e. the most frequent MIC value of each AST method) was found between 21% and 87% (BMD), 46% and 100% (VITEK 2), and 48% and 100% (gradient test) of the repetitions. The range of essential agreement percentage (i.e. ±1 doubling dilution from this mode value) was 53–100% (BMD), 63–100% (VITEK 2), and 100% (gradient test). Percent categorical agreement (same susceptible of resistant category using EUCAST breakpoint v. 14.0) was 71–100% (BMD), 85–92% (VITEK 2), 76–100% (gradient test) and 100% (disk diffusion). Conclusions: : In conclusion, this study provides insight on the reliability of AST results for piperacillin/tazobactam in challenging E. coli isolates. While the results indicate that most methods are generally reproducible, certain isolates may present inconsistent MIC results. |
| format | Article |
| id | doaj-art-58660989b2764da48d388f7fcf4a48c2 |
| institution | DOAJ |
| issn | 2213-7165 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Global Antimicrobial Resistance |
| spelling | doaj-art-58660989b2764da48d388f7fcf4a48c22025-08-20T03:05:41ZengElsevierJournal of Global Antimicrobial Resistance2213-71652025-03-014121121510.1016/j.jgar.2024.12.028Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolatesFaruk Demirocak0Diana Langerak1Erlangga Yusuf2Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The NetherlandsDepartment of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The NetherlandsCorresponding author. Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Dr. Molenwaterplein 40, 3015GD, Rotterdam, The Netherlands.; Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The NetherlandsObjective: Piperacillin/tazobactam antimicrobial susceptibility testing (AST) against Enterobacterales can be challenging. The aim of this study was to assess the reproducibility of various automated (VITEK 2) and nonautomated AST methods (broth microdilution (BMD), minimum inhibitory concentration (MIC) test strip, and disk diffusion) for piperacillin/tazobactam in ‘challenging’ E. coli isolates. Methods: We performed 20 repeated ASTs for seven clinical E. coli isolates: Two resistant to piperacillin/tazobactam but susceptible to amoxicillin/clavulanic acid, four isolates with various β-lactamase coding genes (two blaTEM-1, one blaOXA-1, and one with plasmidal blaampC), and one isolate where VITEK 2 initially could not produce MIC measurements for piperacillin/tazobactam (i.e. no results generated). Results: Upon repetition, the same MIC as the mode value (i.e. the most frequent MIC value of each AST method) was found between 21% and 87% (BMD), 46% and 100% (VITEK 2), and 48% and 100% (gradient test) of the repetitions. The range of essential agreement percentage (i.e. ±1 doubling dilution from this mode value) was 53–100% (BMD), 63–100% (VITEK 2), and 100% (gradient test). Percent categorical agreement (same susceptible of resistant category using EUCAST breakpoint v. 14.0) was 71–100% (BMD), 85–92% (VITEK 2), 76–100% (gradient test) and 100% (disk diffusion). Conclusions: : In conclusion, this study provides insight on the reliability of AST results for piperacillin/tazobactam in challenging E. coli isolates. While the results indicate that most methods are generally reproducible, certain isolates may present inconsistent MIC results.http://www.sciencedirect.com/science/article/pii/S2213716525000050Antimicrobial susceptibility testReproducibilityMinimum inhibitory concentrationVITEKPiperacillin/tazobactamEscherichia coli |
| spellingShingle | Faruk Demirocak Diana Langerak Erlangga Yusuf Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates Journal of Global Antimicrobial Resistance Antimicrobial susceptibility test Reproducibility Minimum inhibitory concentration VITEK Piperacillin/tazobactam Escherichia coli |
| title | Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates |
| title_full | Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates |
| title_fullStr | Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates |
| title_full_unstemmed | Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates |
| title_short | Reliability of various antimicrobial susceptibility testing methods for piperacillin/tazobactam in challenging Escherichia coli isolates |
| title_sort | reliability of various antimicrobial susceptibility testing methods for piperacillin tazobactam in challenging escherichia coli isolates |
| topic | Antimicrobial susceptibility test Reproducibility Minimum inhibitory concentration VITEK Piperacillin/tazobactam Escherichia coli |
| url | http://www.sciencedirect.com/science/article/pii/S2213716525000050 |
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