Introduction: Polymyxins are antimicrobial agents capable of controlling carbapenemase-producing Klebsiella pneumoniae infection.
Methods: We report a cluster of four patients colonized or infected by polymyxin-resistant and Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae.
Results: Three patients were hospitalized in adjacent wards, and two were admitted to the intensive care unit. The index case maintained prolonged intestinal colonization by KPC-producing K. pneumoniae. Three patients received polymyxin B before the isolation of polymyxin-resistant K. pneumoniae.
Conclusions: Colonization by KPC-producing K. pneumoniae and previous use of polymyxin B may be causally related to the development of polymyxin-resistant microorganisms.