Interspecies Transfer of blaIMP-4 in a Patient with Prolonged Colonization by IMP-4-Producing Enterobacteriaceae

A patient was colonized by IMP-4-producing Enterobacter cloacae and Escherichia coli strains for 7 months. IMP-4-producing E. cloacae strains were first and last isolated at day 33 and at 8 months after admission, respectively. IMP-4-producing E. coli strains were first and last isolated at days 88 and 181 after admission, respectively. The E. cloacae and E. coli isolates shared identical genetic features in terms of bla(IMP-4), bla(TEM-1), qnrB2, aacA4, HI2 plasmids, and ISCR1. This study shows the first prolonged colonization with in vivo interspecies transfer of bla(IMP-4).