Optimization of polymyxin B regimens for the treatment of carbapenem-resistant organism nosocomial pneumonia: a real-world prospective study

Abstract Background Polymyxin B is the first line therapy for Carbapenem-resistant organism (CRO) nosocomial pneumonia. However, clinical data for its pharmacokinetic/pharmacodynamic (PK/PD) relationship is limited. This study aimed to investigate the relationship between polymyxin B exposure and efficacy for the treatment of CRO pneumonia in critically ill patients, and to optimize the individual dosing regimens. Methods Patients treated with polymyxin B for CRO pneumonia were enrolled. Blood samples were assayed using a validated high-performance liquid chromatography-tandem mass spectrometry method. Population PK analysis and monte carlo simulation were performed using Phoenix NLME software. Logistic regression analyses and receiver operating characteristic (ROC) curve were employed to identify the significant predictors and PK/PD indices of polymyxin B efficacy. Results A total of 105 patients were included, and the population PK model was developed based on 295 plasma concentrations. AUC ss,24h /MIC (AOR = 0.97, 95% CI 0.95–0.99, p = 0.009), daily dose (AOR = 0.98, 95% CI 0.97–0.99, p = 0.028), and combination of inhaled polymyxin B were independent risk factors for polymyxin B efficacy. ROC curve showed that AUC ss,24h /MIC is the most predictive PK/PD index and the optimal cut-off point value was 66.9. Model-based simulation suggests that the maintaining daily dose of 75 and 100mg Q12 h could achieve ≥ 90% PTA of this clinical target at MIC values ≤ 0.5 and 1 mg/L, respectively. For patients unable to achieve the target concentration by intravenous administration, adjunctive inhalation of polymyxin B would be beneficial. Conclusions For CRO pneumonia, daily dose of 75 and 100 mg Q12h was recommended for clinical efficacy. Inhalation of polymyxin B is beneficial for patients who cannot achieve the target concentration by intravenous administration.