Infections caused by resistant Gram-negative bacteria are seen in increasing frequency. Colistin is used in the treatment of these infections but colistin-resistant bacteria and pan-resistant bacteria have emerged. This situation is thought to become an important health problem in the near future. Various combination therapies are used in the infections caused by pan-resistant bacteria. Double-carbapenem regimen, with or without colistin, is used for this purpose. In this report, we present two different cases of pan-resistant Klebsiella pneumoniae infection, first one developing on a necrotic skin lesion, and second one occurring as central venous catheter-related bacteremia during the treatment of a urinary tract infection, treated with double carbapenems, one of them together with colistin. Klimik Dergisi 2018; 31 (2): 169-72.