Polymyxin B-Based Regimens for Patients Infected with Carbapenem-Resistant Gram-Negative Bacteria: Clinical and Microbiological Efficacy, Mortality, and Safety.

Background: The increasing prevalence of carbapenem-resistant Gram-negative bacteria (CR-GNB) represents a global healthcare crisis. This study explored the efficacy and safety of Polymyxin B (PMB)-based regimens and factors influencing their effectiveness. Methods: Patients with CR-GNB infections treated with PMB for more than three days were enrolled in this retrospective study from 1st June 2018 to 30th April 2020. Data were collected on patient characteristics, bacterial culture, and drug-sensitivity test results; anti-infection treatment regimens, particularly details of PMB use; and adverse drug reactions. Clinical and microbiological efficacy, mortality, and safety of PMB-based regimens in CR-GNB infected patients were evaluated. Univariate analysis and multivariate logistic regression analyses were used to assess factors influencing efficacy and mortality. Results: A total of 373 CR-GNB strains were cultured from 268 patients. About 41.04% of patients used PMB loading dose of 1.01 (0.84-1.69) mg/kg. Maintenance dose was 0.85 (0.82-1.00) mg/kg q12h. The clinical efficacy rate was 36.57% (98/268), the total bacterial clearance rate of PMB was 39.42%, and the all-cause mortality rate was 33.96%. The adverse drug reaction rate was 19.58%, among which the incidence of renal toxicity was highest (8.21%). Multivariate logistic regression analysis showed that clinical efficacy, bacterial clearance rate, and all-cause mortality were associated with patient-related facts, including mechanical ventilation use, underlying diseases (such as respiratory disease), the type and site of CR-GNB infection, and PMB administration timing and loading dose. Conclusion: PMB is a relatively safe and effective antibiotic drug for treatment of critically ill patients with CR-GNB infection; however, PMB use should be subject to guidelines recommendations for early administration, loading administration, and adequate administration, which could help to improve the clinical efficacy, microbiological efficacy, and mortality.