Seventy-three liver abscess isolates of serotype K1 Klebsiella pneumoniae from a nationwide collection in Korea were genotypically characterized using pulsed-field gel electrophoresis and multilocus sequence typing. We found that serotype K1 K. pneumoniae strains that caused liver abscesses in Korea were genotypically related and that most were sequence type 23.Klebsiella pneumoniae has become a major etiologic agent of liver abscess in recent decades, and such an epidemiologic change has been most prominent in Asian countries, including Taiwan and Korea (4,13,18). Meta-analysis of the etiology of pyogenic liver abscesses in Korea has clearly documented that the etiology of pyogenic liver abscesses has continuously changed in this country during the last half-century (4). A recent nationwide Korean study showed that K. pneumoniae accounted for 78.2% of community-acquired liver abscesses in Korea (4). The K. pneumoniae liver abscess has distinctive clinical characteristics, such as a strong association with diabetes mellitus (10, 12) and a high tendency for other metastatic infectious foci (2,4,9). Previous studies have shown that K1 is the predominant serotype among K. pneumoniae isolates that cause liver abscesses in Taiwan and Korea, accounting for around 60% of cases (4, 9). However, the K1 serotype had been uncommon among the clinical isolates before the 1990s (1, 5, 6). Furthermore, infection by this serotype has been more widespread in the Asian countries even though there have been reports addressing a recent increasing role of K. pneumoniae in liver abscess in the United States (8,15,16). To date, there is no explanation for the epidemiological changes and global differences observed.In order to elucidate the reasons for the emergence of serotype K1 K. pneumoniae as a major causative organism for liver abscesses in some Asian countries, molecular characterization of the isolates is essential. In this study, we determined the genotypes of serotype K1 K. pneumoniae liver abscess isolates collected through a prospective nationwide study in Korea and investigated the possibility of regional spread of these invasive strains in Korea.Serotype K1 K. pneumoniae isolates that were collected from community-acquired liver abscesses during a nationwide prospective study by the Korean Study Group for Liver Abscess (4) were included. The residences of the patients were widely distributed throughout the entire country of South Korea. Community-acquired infection was defined as an infection diagnosed within 48 h of admission to the hospital. The K antigen serotype was determined using both slide agglutination testing with antisera (Denka Seiken, Tokyo, Japan) and magA PCR, as previously described (4). Seventy-three liver abscess isolates were randomly selected and were genotyped. Five ATCC reference strains of serotype K1 (ATCC 8044, ATCC 8045, ATCC 8047, ATCC 35593, and ATCC 13886) were also typed for comparison. For pulsedfield gel electrophoresis (PFGE), agarose-embedded bacterial genomic DNA was digested with 20 U o...

2 (i)-ro, Osong-eup, Cheongwon-gun, Chungcheongbuk-do 363-951, Republic of Korea This study was conducted to investigate the molecular characteristics and genetic relatedness of vancomycin-resistant Enterococcus faecium (VREF) isolates obtained from humans and poultry in Korea. A total of 147 VREF isolates from humans (71 clinical isolates) and poultry (76 isolates) in Korea were compared with respect to their antibiotic susceptibilities, organization of the Tn1546 transposon element, detection of virulence genes (esp and hyl), pulsed-field gel electrophoresis (PFGE) typing and multilocus sequence typing (MLST). All of the human and poultry isolates had the vanA gene and 11.3 % (8/71) of the clinical isolates showed the VanB phenotype/vanA genotype. PCR mapping of the Tn1546 elements was different for isolates of the two groups: human isolates were classified into five transposon types, whereas all poultry isolates were identical to Tn1546 of E. faecium strain BM4147. The esp gene was detected in both human (93.0 %, 66/71) and poultry (26.3 %, 20/76) isolates, as was the hyl gene (human isolates: 80.3 %, 57/71; poultry isolates: 26.3 %, 20/76). Using MLST, the 71 human isolates could be divided into ten sequence types (STs) belonging to clonal complex (CC) 17 (except for one singleton). The 76 poultry isolates were categorized into 14 STs and 88.2 % (67/76) of the poultry isolates belonged to CC26. PFGE typing of the human isolates demonstrated diverse PFGE profiles among the strains. However, the PFGE patterns of the poultry isolates were possibly related to the strains collected from individual farms. These data suggest that epidemic clonal groups of human and poultry VREFs in Korea have evolved through different evolutionary processes.