Contributions of insertion sequences conferring colistin resistance in Klebsiella pneumoniae

•Colistin resistance is related to gene alteration and insertional inactivation.•Insertion sequences (ISs) were widely distributed in mgrB and the crrCAB surrounding region.•Klebsiella pneumoniae with ISs would significantly increase frequency of colistin resistance.•High frequency of colistin resistance may increase risk for colistin treatment failure.