Lixia Li,1,* Xiaohui Huang,1,* Jingxian Liu,2,* Chao Li,1 Zhiyan Lin,1 Rongrong Ren,3 Yan Zhang,3 Haoshu Ding,3 Jihui Chen,1 Yanfei Mao3 

1Department of Pharmacy, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; 2Department of Clinical Laboratory, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; 3Department of Anesthesiology and SICU, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Yanfei Mao; Jihui Chen, Email maoyanfei@xinhuamed.com.cn; chenjihui@xinhuamed.com.cn

Background: Polymyxin B (PMB)-based combination therapies are used to treat severe carbapenem-resistant gram-negative bacterial (CR-GNB) infections. This observational study investigated the relationship between clinical factors, including PMB concentration, and clinical efficacy and safety.
Patients and Methods: Polymyxin B regimens were optimized through therapeutic drug monitoring (TDM) and area under the concentration-time curve (AUC). In all, 382 samples were tested from 130 patients. Logistic regression was used to analyze the relationships between variables with clinical efficacy and 30-day mortality factors were analyzed by Cox regression. The sensitivity and specificity of Cmin and AUC for the occurrence of acute kidney injury (AKI) were determined by ROC curve analysis.
Results: The clinical effectiveness of PMB was 65.4%. Multivariate logistic regression analysis revealed that lung infection, continuous renal replacement therapy, and C-reactive protein were independent factors significantly associated with efficacy. AKI occurred in 14.6% of the patients during treatment; age > 73 years (OR: 3.63; 95% CI: 1.035– 12.727; P = 0.044), Cmin greater than 2.3 μg/mL (OR: 7.37; 95% CI: 1.571– 34.580; P = 0.011), combined vancomycin (OR: 9.47; 95% CI: 1.732– 51.731; P = 0.009), and combined piperacillin-tazobactam (OR: 21.87; 95% CI: 3.139– 152.324; P = 0.002) were independent risk factors. The identified PMB cut-offs for predicting AKI were Cmin = 2.3 μg/mL and AUC = 82.0 mg h/L.
Conclusion: Polymyxin B-based combination regimens are effective in treating CR-GNB infections, particularly bloodstream infections, but have shown unsatisfactory for lung infections. Cmin ≥ 2.3 μg /mL and AUC ≥ 82.0 mg h/L may increase PMB-associated AKI incidence. PMB dose should be adjusted based on TDM to ensure efficacy.

Keywords: Polymyxin B, PMB therapeutic drug monitoring, TDM, carbapenem-resistant gram-negative bacteria, CR-GNB, clinical efficacy, acute kidney injury, AKI