title: Genotypes and virulence in serotype K2 Klebsiella pneumoniae from liver abscess and non-infectious carriers in Hong Kong, Singapore and Taiwan.
abstract: In Klebsiella pneumoniae liver abscess (KP-LA), K. pneumoniae K2 is the most frequently isolated serotype after K1, but this serotype has been much less studied. In the present study, the molecular types sequences type (MLST) of serotype K2 isolates from three different regions in Asia were identified and the virulence of these isolates was investigated. Eight different MLSTs were found among 26 isolates (ST 65, 66, 86, 373, 374, 375, 380, and 434). There were two major MLST groups, ST-65-like (42%) and ST86-like (46%). No isolates contained allS while all isolates contained rmpA. The prevalence of aerobactin gene and kfu were 25/26 (96%) and 3/26 (11.5%) respectively. Although liver abscess isolates were generally more resistant (11/15 isolates) to serum killing, there was no specific distribution of serum killing resistant or susceptible ST types between stool carriage and liver abscess isolates. Neutrophil phagocytosis showed that the liver abscess and carriage isolates varied in their susceptibility to phagocytosis. Strains with resistance to both neutrophil phagocytosis and serum killing were generally hypervirulent with lethality at LD50 < 10(3) colony forming units by intraperitoneal injection. In conclusion, Anti-phagocytosis and resistance to serum killing are two parameters that most predict hyperviurlence in serotype K2 isolates. Unlike serotype K1 KP-LA that mainly belong to ST-23, ST-65-like and -86-like are the two major MLST types among serotype K2 isolates from Singapore, Hong Kong and Taiwan.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore, Singapore.
authors.forename: Tse Hsien
authors.initials: TH
authors.lastname: Koh
authors.affiliation: Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: Nelson
authors.initials: N
authors.lastname: Lee
authors.affiliation: Department of Medicine, Section of Infectious Diseases, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 350, Taiwan.
authors.forename: Yu-Kuo
authors.initials: YK
authors.lastname: Tsai
authors.affiliation: Department of Microbiology, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, SAR, People's Republic of China.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ip
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan ; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 350, Taiwan ; Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: L Kristopher
authors.initials: LK
authors.lastname: Siu
keywords: Klebsiella pneumoniae; Liver abscess; MLST