A cluster of carbapenemase-producing Enterobacter cloacae complex ST171 at a tertiary care center demonstrating an ongoing regional threat

BACKGROUND: In Minnesota and North Dakota, a clonal strain of bla KPC-3-producing Enterobacter cloacae complex has been reported with increasing frequency.

METHODS: Between July 2015 and February 2016, 13 carbapenem-resistant E. cloacae complex isolates were identified at our institution. Five bla KPC-positive isolates were identified by polymerase chain reaction and underwent pulsed-field gel electrophoresis and whole genome sequencing. Medical records of these patients were reviewed.

RESULTS: All 5 case-isolates belonged to sequence type 171 and were bla KPC-3-positive. Three pulsed-field gel electrophoresis patterns with >90% similarity were identified in the 5 case-isolates. We identified overlaps in time and location between case patients. Plasmid types and resistance genes were nearly identical between the isolates. Whole genome sequencing showed isolates A, B, and D to be closely related with <10 core single-nucleotide polymorphisms differences. Isolates C and E were also closely related to each other, but more distantly to A, B, and D; all belonged to the clonal lineage of the major circulating E. cloacae complex strain in Minnesota and North Dakota. Despite having overlapping hospital stays, isolates for patients C and D were not identical.

CONCLUSIONS: Isolates A and D were nearly identical, indicating possible transmission during hospitalization. Transmission of the other isolates may have occurred elsewhere. This report highlights the importance of using both epidemiologic and molecular data to track the spread of carbapenemase-producers.