1. Defining optimal sulbactam regimens for treatment of Acinetobacter baumannii pneumonia and impact of blaOXA-23 on efficacy.
- Author
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Abouelhassan, Yasmeen, Nicolau, David P, and Abdelraouf, Kamilia
- Subjects
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ACINETOBACTER baumannii , *LUNGS , *NEUTROPENIA , *PNEUMONIA , *SEPTEMBER 11 Terrorist Attacks, 2001 - Abstract
Objectives We evaluated the efficacies of human-simulated regimens (HSRs) of two clinically utilized sulbactam regimens: 1 g q6h 0.5 h infusion (maximum FDA-approved dosage) and 3 g q8h 4 h infusion (high-dose, prolonged-infusion regimen), against Acinetobacter baumannii in a translational murine model. Methods Thirty-two clinical A. baumannii isolates were investigated, of which 16 were sulbactam resistant (MIC ≥ 16 mg/L), 6 were sulbactam intermediate (MIC = 8 mg/L) and 10 were sulbactam susceptible (MIC ≤ 4 mg/L). Efficacies of the two sulbactam HSRs were assessed in the neutropenic murine pneumonia model. Changes in log10 cfu/lungs at 24 h compared with 0 h controls were measured, and efficacy was defined as achieving 1 log kill relative to baseline. WGS of the isolates and bioinformatics analysis were performed to explore potential associations between the genomic backgrounds and the in vivo responses. Results Eleven isolates harboured bla OXA-23, of which 10 were sulbactam resistant, 1 was sulbactam intermediate while none was sulbactam susceptible. Both sulbactam HSRs achieved >1 log kill against sulbactam-susceptible isolates. Against sulbactam-intermediate and sulbactam-resistant isolates, lack of efficacy correlated with the presence of the bla OXA-23 gene; sulbactam 1 g HSR and 3 g HSR did not show efficacy against 11/11 and 9/11 bla OXA-23-positive isolates, respectively, while efficacy was observed against all 11 bla OXA-23-negative sulbactam-intermediate and sulbactam-resistant isolates (i.e. harbouring other resistance genes). Conclusions A sulbactam high-dose prolonged-infusion regimen provides comparable activity to the standard dose against isolates currently considered sulbactam susceptible. However, the activity against isolates with intermediate and resistant susceptibility could be predicted by the detection of bla OXA-23. Enhancing detection capabilities of common diagnostic modalities to include OXA-23 can improve patient outcome. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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