Optimization of pulse-field gel electrophoresis for subtyping of Klebsiella pneumoniae

A total of 110 strains of Klebsiella pneumoniae were used to optimize pulsed-field gel electrophoresis (PFGE) for subtyping of K. pneumoniae. For optimization of electrophoresis parameters (EPs) of XbaI-PFGE, 11 isolates were analyzed with XbaI digestion using three EPs. The EP of a switch time of 6 to 36 s for 18.5 h gave clearest patterns and was declared the optimal EP for XbaI PFGE of K. pneumoniae. By software analysis and pilot study, AvrII was chosen as another PFGE enzyme. Both XbaI- and AvrII-PFGE gave D-values higher than 0.99 for 69 K. pneumoniae isolated from different sources. Our results also showed good typeability, reproducibility of both XbaI- and AvrII-PFGE for K. pneumoniae subtyping. Furthermore, the established PFGE method also had good discriminatory power to distinguish outbreak K. pneumoniae strains and a high degree of consistency with multilocus sequence typing method. A rapid PFGE protocol was established here, which could be used for genotyping and other researches of K. pneumoniae.