Carbapenems are a class of antibiotic agents which kill a broad spectrum of bacteria. Infections due to gram-negative bacteria which have acquired resistance to carbapenems are increasing, especially with Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa . The optimal treatment of such infections is not known. Antibiotics like polymyxin, tigecycline and rifampin are used alone or in combination with other antibiotics. The outcome of using these new and old drugs is not well studied. This observational study aims to study the clinical and microbiological outcomes of these infections and treatment at our institution.