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Harris H, Tao L, Jacobs EB, Bergman Y, Adebayo A, Tekle T, Lewis S, Dahlquist A, Abbey TC, Wenzler E, Humphries R, Simner PJ. Multicenter Evaluation of an MIC-Based Aztreonam and Ceftazidime-Avibactam Broth Disk Elution Test. J Clin Microbiol 2023; 61:e0164722. [PMID: 37070979 PMCID: PMC10204635 DOI: 10.1128/jcm.01647-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/22/2023] [Indexed: 04/19/2023] Open
Abstract
Due to limited therapeutic options, there is a clinical need to assess the in vitro activity of the combination of aztreonam (ATM) and ceftazidime-avibactam (CZA) to guide the therapeutic management of multidrug-resistant (MDR) Gram-negative organism infections. We set out to develop a practical MIC-based broth disk elution (BDE) method to determine the in vitro activity of the combination ATM-CZA using readily available supplies and compare it to reference broth microdilution (BMD). For the BDE method, a 30-μg ATM disk, a 30/20-μg CZA disk, both disks in combination, and no disks were added to 4 separate 5-mL cation-adjusted Mueller-Hinton broth (CA-MHB) tubes, using various manufacturers. Three testing sites performed both BDE and reference BMD testing of bacterial isolates in parallel from a single 0.5 McFarland standard inoculum and after overnight incubation, assessed them for growth (not susceptible) or no growth (susceptible) at a final concentration of 6/6/4 μg/mL ATM-CZA. During the first phase, the precision and accuracy of the BDE were analyzed by testing 61 Enterobacterales isolates at all sites. This testing yielded 98.3% precision between sites, with 98.3% categorical agreement and 1.8% major errors (ME). During the second phase, at each site, we evaluated unique, clinical isolates of metallo-β-lactamase (MBL)-producing Enterobacterales (n = 75), carbapenem-resistant Pseudomonas aeruginosa (n = 25), Stenotrophomonas maltophilia (n = 46), and Myroides sp. (n = 1). This testing resulted in 97.9% categorical agreement, with 2.4% ME. Different results were observed for different disk and CA-MHB manufacturers, requiring a supplemental ATM-CZA-not-susceptible quality control organism to ensure the accuracy of results. The BDE is a precise and effective methodology for determining susceptibility to the combination ATM-CZA.
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Affiliation(s)
- Harley Harris
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lili Tao
- Department of Pathology, Microbiology, and Immunology, Division of Laboratory Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Emily B. Jacobs
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Yehudit Bergman
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ayomikun Adebayo
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Tsigedera Tekle
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shawna Lewis
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ashley Dahlquist
- College of Pharmacy, University of Illinois Chicago, Chicago, Illinois, USA
| | - Taylor C. Abbey
- College of Pharmacy, University of Illinois Chicago, Chicago, Illinois, USA
| | - Eric Wenzler
- College of Pharmacy, University of Illinois Chicago, Chicago, Illinois, USA
| | - Romney Humphries
- Department of Pathology, Microbiology, and Immunology, Division of Laboratory Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Patricia J. Simner
- Department of Pathology, Division of Medical Microbiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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