Methods: MICs were determined by BSAC agar dilution methodology. Carbapenem-resistant isolates lacking imipenem/EDTA synergy were tested by PCR for blaKPC. Multi-locus sequence typing and blaKPC sequencing was performed on a subset of isolates. Plasmid analysis was performed by transformation, PCR-based replicon typing and, in some cases, whole-plasmid sequencing. Patient data provided by the sending laboratories were reviewed.
Results: Two hundred and ten KPC-producing isolates were submitted from 71 UK laboratories outside North-West England, representing 160 patients. All were Enterobacteriaceae, predominantly K. pneumoniae (82%; 172/210), and most (91%; 191/210) were obtained from hospitalised patients. Analysis of 123 isolates identified blaKPC-2 (64%; 79/123), blaKPC-3 (27%; 33/123) and blaKPC-4 (9%; 11/123). Within K. pneumoniae, clonal group (CG) sequence type (ST) 258 was dominant (64%; 54/84), however 21 unrelated STs were also identified. Plasmid analysis identified a diverse range of plasmids of at least 11 different replicon types, found in multiple STs and species.
Conclusions: KPC enzymes are increasingly detected in Enterobacteriaceae in the UK outside North-West England, despite a lack of reported outbreaks. K. pneumoniae CG258 are the dominant hosts although plasmid spread also plays a significant role in dissemination of KPCs between other K. pneumoniae STs and enterobacterial species.