Efficacy of Polymyxin B Against Infections Caused by Extensively Drug-resistant (XDR) Gram-Negative Bacteria

Inclusion Criteria: * Age 18-75 year-old * The infection caused by carbapenem-resistant (CR) Enterobacteriaceae, CR P.aeruginosa or CR A. baumannii which susceptible to colistin * The duration of treatment approximately between 7-14 days * Kidney function, according to Kidney Disease Improving Global Outcomes (KDIGO) classification, should less than stage 4 and no replacement therapy in all modality. * The patients are anticipated to live more than 48 hrs after participation. * In case of Colistin administration beforehand, it should not exceed 24 hrs. * All of participants should be willing to join this project. Exclusion Criteria: * Pregnancy and lactation * End stage renal disease who take renal replacement therapy * Any type of Neuromuscular disease * Body mass index exceed 30 * Infection that require treatment more than 14 days