Polymyxin B clinical outcomes: A prospective study of patients undergoing intravenous treatment.

What Is Known And Objective: Polymyxins, especially polymyxin B, has become the last line of therapy against Gram-negative pathogens' carbapenemase producers. However, given increasing use of polymyxin B in clinical settings its therapeutic value has been evaluated worldwide due to its toxic effects. The aim of this study was to assess the efficacy and safety of antimicrobial therapy with polymyxin B in patients with multidrug-resistant bacteria in Brazil.

Methods: This was a prospective cohort study in a 403-bed academic tertiary care centre, located in the countryside of Brazil. Patients receiving polymyxin B intravenous treatment for at least 72 hours were eligible for the study. Antimicrobial susceptibility, adverse reactions and clinical outcomes were submitted for descriptive analysis. Main outcomes measure the following: Patients' conditions following treatment (Treatment Success, Mortality, Treatment Failure, Inadequate Empiric Treatment or Indeterminate Response) and toxicities induced by polymyxin B (nephrotoxicity and skin hyperpigmentation).

Results And Discussion: Among 247 patients, treatment success was achieved in 25.1%, while mortality was observed in 32.8%. Empirical therapy was prescribed for 26.3% of the patients. Nephrotoxicity was reported in 40.5%. The carbapenemase producer, Klebsiella pneumonia, was the bacterium most associated with mortality (22.2%).

Conclusions: Even though polymyxin B is currently the main therapy against carbapenemase producers, its use demands robust criteria to lead to positive clinical outcomes.