title: Increasing opsonizing and killing effect of serum from patients with recurrent K1 Klebsiella pneumoniae liver abscess.
abstract: BACKGROUND
  Klebsiella pneumoniae liver abscess (KLA) is an emerging infectious disease caused by the virulent K pneumoniae strains of capsular serotype K1 and commonly associated with diabetes mellitus. Recurrent KLA is rarely reported and the mechanism of recurrence is uncertain. In this study we evaluated both phagocytosis by neutrophils and serum killing ability of serum from recurrent K1 KLA patients compared to normal healthy subjects (NHS).
  
  
  METHODS
  This prospective study included six cases of recurrent K1 KLA consisting of three male and three female patients with a mean age of 67.2 years (range, 56-88 years). The different serotypes of K pneumoniae were reacted with serum from patients with recurrent KLA and NHS. Subsequent phagocytosis by neutrophils was determined using flow cytometry and serum killing assays were performed.
  
  
  RESULTS
  The most common underlying disease in patients with recurrent KLA was diabetes mellitus, occurring in about 83.3% (5/6) of patients. The antibiogram of the strains associated with recurrent KLA remained uniquely resistant to ampicillin. The average percentage derived from the serum killing assays showed serotype K1 and K2 resistance to serum from NHS (1281% and 621%, respectively); however, serum susceptibly was observed in the serum of patients with recurrent K1 KLA (0.3% and 1.1%, respectively). A significant increase in neutrophil phagocytosis of serotype K1 was observed following opsonisation with serum from patients with recurrent KLA compared with serum from NHS (p = 0.008). No significant difference in the phagocytic rate of non-K1/K2 or K2 serotypes was observed between NHS and patients with recurrent KLA (p = 0.76 and p = 0.132, respectively).
  
  
  CONCLUSIONS
  These preliminary results showed possible immunologic protection in patients with recurrent KLA due to increasing opsonization and serum killing.
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: Fang-Ching
authors.initials: FC
authors.lastname: Yeh
authors.forename: Kao-Ming
authors.initials: KM
authors.lastname: Yeh
authors.forename: L K
authors.initials: LK
authors.lastname: Siu
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
authors.forename: Ya-Sung
authors.initials: YS
authors.lastname: Yang
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial; D016667:Bacterial Capsules / Q000032:analysis* / Q000276:immunology; D001770:Blood Bactericidal Activity; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007710:Klebsiella Infections / Q000276:immunology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000737:chemistry / Q000276:immunology*; D008100:Liver Abscess / Q000276:immunology* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology; D009895:Opsonin Proteins / Q000276:immunology*; D010587:Phagocytosis; D011135:Polysaccharides, Bacterial; D011446:Prospective Studies; D012008:Recurrence
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D009895:Opsonin Proteins; D011135:Polysaccharides, Bacterial; C036962:capsular polysaccharide K1