title: Do neutrophils play a role in establishing liver abscesses and distant metastases caused by Klebsiella pneumoniae?
abstract: Serotype K1 Klebsiella pneumoniae is a major cause of liver abscesses and endophthalmitis. This study was designed to identify the role of neutrophils in the development of distant metastatic complications that were caused by serotype K1 K. pneumoniae. An in vitro cellular model was used to assess serum resistance and neutrophil-mediated killing. BALB/c mice were injected with neutrophils containing phagocytosed K. pneumoniae. Serotype K1 K. pneumoniae was significantly more resistant to serum killing, neutrophil-mediated phagocytosis and intra-cellular killing than non-K1 isolates (p<0.01). Electron microscopic examination had similar findings as in the bioassay findings. Intraperitoneal injection of neutrophils containing phagocytosed serotype K1 K. pneumoniae led to abscess formation in multiple sites including the subcutaneous tissue, lung, and liver, whereas no abscess formation was observed in mice injected with non-K1 isolates. The resistance of serotype K1 K. pneumoniae to complement- and neutrophil-mediated intracellular killing results in the dissemination of K. pneumoniae via the bloodstream. Escape from neutrophil intracellular killing may contribute to the dissemination and establishment of distant metastases. Thus, neutrophils play a role as a vehicle for helping K. pneumoniae and contributing to the establishment of liver abscess and distant metastatic complications.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, and Institute of Clinical Medicine, School of Medicine, Naitonal Yang-Ming University, Taipei, Taiwan.
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
authors.forename: Kuo-Ming
authors.initials: KM
authors.lastname: Yeh
authors.forename: Chiung-Tong
authors.initials: CT
authors.lastname: Chen
authors.forename: Yu-Kuo
authors.initials: YK
authors.lastname: Tsai
authors.forename: L Kristopher
authors.initials: LK
authors.lastname: Siu
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D006801:Humans; D007668:Kidney / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D007710:Klebsiella Infections / Q000276:immunology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000145:classification / Q000276:immunology* / Q000648:ultrastructure; D008099:Liver / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008100:Liver Abscess / Q000276:immunology* / Q000382:microbiology / Q000401:mortality; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D009504:Neutrophils / Q000276:immunology* / Q000382:microbiology / Q000637:transplantation; D010587:Phagocytosis / Q000276:immunology; D018805:Sepsis; D012703:Serotyping; D044967:Serum / Q000276:immunology; D013154:Spleen / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D015996:Survival Rate