Arrival of Klebsiella pneumoniae producing KPC carbapenemase in the United Kingdom

Background: KPC-type carbapenemases are increasingly prevalent in parts of the USA and Israel and are an emerging concern in South America, Europe and China. We investigated the UK's first two KPC-producing Klebsiella pneumoniae isolates. Methods: The isolates were referred to the UK's national reference laboratory for confirmation of carbapenem resistance. Susceptibilities were determined by agar dilution, and bla_KPC and Tn 4401-like elements were sought by PCR and sequencing. Isolates were compared by PFGE of Xba I- and Spe I-digested genomic DNA. Results: The isolates were from patients in different UK hospitals, with no epidemiological connection. Both were resistant to carbapenems (MICs > 16 mg/L), with imipenem MICs unchanged by EDTA, and also to all other β-lactams (including inhibitor combinations), tobramycin, amikacin and ciprofloxacin. They were susceptible to gentamicin (MICs ≤ 1 mg/L) and colistin (MICs ≤ 0.5 mg/L), with intermediate susceptibility to tigecycline (MICs 1-2 mg/L). The isolates belonged to the same PFGE-defined strain, highly related to a disseminated KPC-producing strain characterized previously in Tel Aviv, Israel. Like this Israeli strain, the UK isolates produced KPC-3 carbapenemase, with the bla_KPC-3 gene located within a Tn 4401-like element. Conclusions: The first KPC-3-producing K. pneumoniae isolates detected in the UK were highly genetically related to a KPC-3-producing Israeli K. pneumoniae strain. This relatedness was consistent with the history of one UK patient, who had been hospitalized previously in Israel. However, this strain may be circulating more widely since the second UK patient had no identifiable links with Israel or other overseas countries.