Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods
Abstract
1. Introduction
2. Results
2.1. Comparison with Broth Disk Elution Test
2.2. Comparison of MIC Distribution for AZA Disk Diffusion Test, AZA MIC Test Strip, and Gradient MIC Test Strips
3. Discussion
3.1. Clinical Isolates
3.2. Comparison of Methods for Routine Laboratory Use
3.3. Clinical Application for Guiding Antibiotic Use
3.4. Limitations and Future Directions
4. Materials and Methods
4.1. Strain Collection
4.2. The CLSI Aztreonam Plus Ceftazidime–Avibactam Broth Disk Elution Method (BDE)
4.3. Disk Diffusion Method for Aztreonam–Avibactam
4.4. MIC Test Strip Method for Aztreonam–Avibactam
4.5. Gradient Strip Stacking Method
4.6. Statistical Analysis
- CA refers to strains where the evaluated method yielded an AST result with the same categorical interpretation as the standard of comparison. CA ≥ 90% is considered acceptable.
- VME refers to strains tested resistant by the standard of comparison but tested susceptible by the method under evaluation. VME < 3% is considered acceptable.
- ME refers to strains tested susceptible by the standard of comparison but tested resistant by the method under evaluation. ME < 3% is considered acceptable.
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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AZA Disk Diffusion | AZA MIC Test Strip | Gradient Strip Stacking | |
---|---|---|---|
CA | 100% | 100% | 100% |
VME | 0% | 0% | 0% |
ME | 0% | 0% | 0% |
ATM MIC (µg/mL) | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
0.016 | 0.032 | 0.064 | 0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | ||
Aztreonam–avibactam MIC (µg/mL) | 0.032 | 1 | 1 | |||||||||
0.064 | 4 | 6 | 5 | 3 | 1 | |||||||
0.125 | 1 | 1 | 2 | 3 | 2 | 1 | 1 | |||||
0.25 | 1 | 1 | ||||||||||
0.5 | ||||||||||||
1 | 3 | 1 | ||||||||||
2 | ||||||||||||
4 | 1 | |||||||||||
8 | ||||||||||||
16 | ||||||||||||
32 | ||||||||||||
64 | ||||||||||||
128 | 1 |
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Chan, L.M.-W.; Lok, D.Y.L.; Wong, R.C.W.; Lee, A.L.-H.; Cheung, I.Y.-Y.; Lai, C.K.-C.; Chow, V.C.Y. Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods. Antibiotics 2025, 14, 675. https://doi.org/10.3390/antibiotics14070675
Chan LM-W, Lok DYL, Wong RCW, Lee AL-H, Cheung IY-Y, Lai CK-C, Chow VCY. Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods. Antibiotics. 2025; 14(7):675. https://doi.org/10.3390/antibiotics14070675
Chicago/Turabian StyleChan, Linda Mei-Wah, Doris Yui Ling Lok, River Chun Wai Wong, Alfred Lok-Hang Lee, Ingrid Yu-Ying Cheung, Christopher Koon-Chi Lai, and Viola C. Y. Chow. 2025. "Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods" Antibiotics 14, no. 7: 675. https://doi.org/10.3390/antibiotics14070675
APA StyleChan, L. M.-W., Lok, D. Y. L., Wong, R. C. W., Lee, A. L.-H., Cheung, I. Y.-Y., Lai, C. K.-C., & Chow, V. C. Y. (2025). Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods. Antibiotics, 14(7), 675. https://doi.org/10.3390/antibiotics14070675