Mutant prevention concentration of tigecycline for Klebsiella pneumoniae isolates with four different resistance statuses.

Dear Editor, Klebsiella pneumoniae (K. pneumoniae) is one of the most important causes of healthcare-associated infections, especially among hospitalized patients [1]. Since most clinical isolates of K. pneumoniae are resistant to fluoroquinolones and carbapenems, clinicians have to use tigecycline as the last resort. Unfortunately, the prevalence of tigecycline-resistant K. pneumoniae seems to be increasing [2,3]. The potential development of resistance to tigecycline during treatment is of concern. In this study, in order to determine whether tigecycline restricts the selective enrichment of resistant mutant subpopulations of K. pneumoniae, we measured the mutant prevention concentrations (MPCs) of tigecycline for 91 K. pneumoniae clinical isolates with four different resistance statuses, and assessed their propensity of developing resistance to tigecycline.