In vitro activity of tigecycline in combination with rifampin, doripenem or ceftazidime against carbapenem-resistant Klebsiella pneumoniae bloodstream isolates

Klebsiella pneumoniae is one of the most significant nosocomial pathogens in healthcare settings. Over the last decade, K. pneumoniae producing extended-spectrum β-lactamases (ESBLs) have been prevalent worldwide. ESBL-producing isolates are considered resistant to all penicillins, cephalosporins and aztreonam, and carbapenems are the only β-lactams that still remain consistently active.1 But owing to the overuse of carbapenems, resistant strains have become endemic in many countries as well. In addition, most carbapenem-resistant K. pneumoniae (CR-KP) are resistant to other antimicrobial classes, referred to as multidrug-resistant (MDR) and extensively drug-resistant strains.2 The lack of active antimicrobials against CR-KP continues to threaten public health.