Plasmid analysis of clinically isolated Enterobacter cloacae in Showa University Hospital

Abstract

We have reported the possibility of an outbreak of a plasmid-borne carbapenemase-producing Enterobacteriaceae at Showa University Hospital using conjugal transfer experiments ; however, we could not perform plasmid profiling and fingerprinting to identify the plasmid responsible for the outbreak in clinical isolates. Therefore, to distinguish whether the appearance of metallo- β -lactamase IMP-11 （ bla IMP-11 ） -producing Enterobacter cloacae （ E. cloacae ） was due to the same plasmid, we established a plasmid testing system involving plasmid isolation, typing, profiling, and fingerprinting, as well as DNA sequencing analysis of genes surrounding the carbapenemase-encoding gene. Plasmid fingerprinting is an essential tool for identifying plasmids when next-generation sequencing methods cannot be employed. Of note, an important step in fingerprinting is plasmid isolation, which is difficult when large plasmids are involved. In addition, plasmid profiling using S1 nuclease pulse-field gel electrophoresis （ PFGE ） Southern blotting important tool for profiling the size and number of plasmids in bacteria. study, we isolated an approximately 90-kb IncL/M plasmid by employing our plasmid analysis system. different MP-11 -producing of similar size and fingerprinting pattern, we suggest the IncL/M plasmid in