High prevalence of phagocytic-resistant capsular serotypes of Klebsiella pneumoniae in liver abscess.
To better understand the role of capsular polysaccharide (CPS) K1 or K2 in Klebsiella pneumoniae liver abscess as well as the development of metastasis to eye, neutrophil phagocytosis of 70 CPS isolates including K1 (n = 23)/K2 (n = 10), non-K1/K2 (n = 37) was evaluated by flow cytometry, fluorescence imaging, and electron microscopy. K1/K2 isolates were significantly more resistant to phagocytosis (P < 0.0001) than non-K1/K2 isolates and displayed increased resistance to intracellular killing. Although mucoid phenotype (M-type) K1/K2 isolates were significantly more resistant to phagocytosis (P = 0.0029) than M-type non-K1/K2, no significant difference in the phagocytosis rate was observed between K1/K2 isolates with M-type and non-M-type (P = 0.0924). Mucoidy is an associated factor that was predominant in K1/K2 isolates, but which itself is not an independent influence on phagocytic resistance. The K1/K2 CPS proved significantly more resistant to phagocytosis than non-K1/K2 CPS in liver abscess isolates (P < 0.0001) and non-abscess isolates (P = 0.0001), suggesting that K1/K2 isolates were generally more virulent in both liver abscess and in non-liver abscess conditions. These findings indicate that resistance of CPS K1 or K2 K. pneumoniae to phagocytosis and intracellular killing presumably contributes to their high prevalence in liver abscess and uniquely in endophthalmitis.
Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, Taipei, Taiwan.
Jung-Chung
JC
Lin
Feng-Yee
FY
Chang
Chang-Phone
CP
Fung
Jin-Zhen
JZ
Xu
Hsiao-Pei
HP
Cheng
Jaang-Jiun
JJ
Wang
Li-Yueh
LY
Huang
L K
LK
Siu
D000942:Antigens, Bacterial / Q000276:immunology; D016667:Bacterial Capsules / Q000276:immunology*; D001769:Blood / Q000382:microbiology; D005434:Flow Cytometry; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000276:immunology / Q000472:pathogenicity*; D008100:Liver Abscess / Q000382:microbiology*; D008854:Microscopy, Electron; D009504:Neutrophils / Q000276:immunology; D010587:Phagocytosis; D011135:Polysaccharides, Bacterial / Q000276:immunology; D012703:Serotyping; D013183:Sputum / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000276:immunology; D014947:Wounds and Injuries / Q000382:microbiology
D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; D037521:Virulence Factors; C036962:capsular polysaccharide K1; C068924:capsular polysaccharide K2