ABSTRACT
Emergence of resistant strain to antimicrobials is a growing problem worldwide. Here, we report a case of multidrug-resistant Klebsiella pneumoniae and Acinectobacter baumannii, Gram-negative bacilli, which was only intermediate sensitive to colistin; a polymyxin E. Colistin has attracted more interest recently because of its significant activity against multi-resistant Pseudomonas aeruginosa, A. baumannii and K. pneumoniae, and the low resistance rates to it. The decrease in sensitivity of colistin against K. pneumoniae and A. baumanni sends alarming signals for the development of resistance to this antimicrobial drug. It is likely that colistin the important antimicrobial option against multi-resistant Gram-negative bacteria will be lost.