Escherichia coli O104:H4 from 2011 European Outbreak and Strain from South Korea

To the Editor: Beginning in early May 2011, an outbreak caused by Shiga toxin–producing Escherichia coli O104:H4 was reported in Germany and other countries in Europe. In this outbreak, the number of hemolytic uremic syndrome (HUS) cases has been unusually high (1). As of June 9, 2011, a total of 722 cases of HUS, 19 deaths, and 2,745 cases of enterohemorrhagic E. coli (EHEC) infection were reported (2). A case of HUS caused by E. coli O104:H4 was fi rst reported in South Korea in 2004 (3). Because infections caused by E. coli O104:H4 have been reported rarely, interest has arisen in the E. coli O104:H4 strain from South Korea. We characterized the E. coli O104:H4 strain isolated in South Korea (EC0417119) in 2004 and compared it with the E. coli O104:H4 strain associated with the current EHEC outbreak in Europe. The serotype EC0417119, isolated from a patient with HUS in 2004, was reconfi rmed as E. coli O104:H4. The strain was positive for stx1 and stx2 by PCR (4) but negative for aggR by PCR (5). In the antimicrobial drug susceptibility test using VITEK 2 AST-N169 test kit (bioMérieux, Marcy L’Etoile, France), the strain was resistant to ampicillin, ampicillin/sulbactam, and trimethoprim/sulfamethoxazole but susceptible to ceftriaxone, cefotaxime, nalidixic acid, and tetracycline. We also performed pulsedfi eld gel electrophoresis (PFGE) for EC0417119, according to the PulseNet standard protocol (6), and compared its PFGE profi le with that of the current outbreak strain E. coli O104:H4, which was obtained from the PulseNet Asia Pacifi c network. PFGE profi les resolved by either XbaI or BlnI did not match each other. The percentage similarity of XbaIand BlnI-digested PFGE profi les of the 2 isolates was 75% and 66.7%, respectively, as shown in the Figure. Infections with the EHEC O104 strain were reported several times worldwide. In Europe, such occurrence was rare, and before the current outbreak, the EHEC O104:H4 strain was documented only once in South Korea. For this reason, it was logical to examine the possible relatedness of the EC0417119 strain and the strain causing the current outbreak. However, the EC0417119 strain has many different characteristics compared with the current outbreak strain: not possessing enteroaggregative E. coli determinant, not producing extended-spectrum β-lactamases, and not showing indistinguishable PFGE patterns. In conclusion, there is no evidence that the E. coli O104:H4 strain isolated in South Korea in 2004 is related to the strain that has a caused the massive and unprecedented EHEC outbreak in Europe.