title: Comparison of prevalence of virulence factors for Klebsiella pneumoniae liver abscesses between isolates with capsular K1/K2 and non-K1/K2 serotypes.
abstract: Hypermucoviscosity, rmpA (regulator of mucoid phenotype), aerobactin (an iron siderophore), kfu (an iron uptake system), allS (associated with allantoin metabolism), and K1/K2 capsules are important virulence determinants in Klebsiella pneumoniae for liver abscesses. We determined the prevalence of these virulence factors of 50 nonrepeat K. pneumoniae isolates recovered from patients with primary liver abscesses who were treated at 2 medical centers in Taiwan. Virulence genes were surveyed by polymerase chain reaction analysis. The prevalence of hypermucoviscosity phenotype, plasmid-born rmpA, aerobactin, kfu, and allS genes revealed 96%, 100%, 100%, 100%, and 100% in 26 capsular K1 isolates; 90%, 100%, 100%, 0%, and 0% in 10 K2 isolates; and 79%, 86%, 93%, 50%, and 0% in 14 non-K1/K2 isolates; respectively. When injected into mice intraperitoneally, regardless of any capsule K serotype, K. pneumoniae isolates with hypermucoviscosity phenotype as well as presence of rmpA and aerobactin genes exhibited high virulence for mouse lethality (LD(50), <10(2) CFU). Without significant difference in the prevalence of expressing hypermucoviscosity phenotype and carriage of rmpA and aerobactin genes, these virulent non-K1/K2 isolates are as capable as K1/K2 isolates of causing primary liver abscesses.
authors.affiliation: Department of Intensive Care Medicine, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Yu
authors.forename: Wen-Chien
authors.initials: WC
authors.lastname: Ko
authors.forename: Kuo-Chen
authors.initials: KC
authors.lastname: Cheng
authors.forename: Ching-Chien
authors.initials: CC
authors.lastname: Lee
authors.forename: Chien-Cherng
authors.initials: CC
authors.lastname: Lai
authors.forename: Yin-Ching
authors.initials: YC
authors.lastname: Chuang
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial; D016667:Bacterial Capsules; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000378:metabolism; D007710:Klebsiella Infections / Q000453:epidemiology / Q000821:virology; D007711:Klebsiella pneumoniae / Q000145:classification* / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D008100:Liver Abscess / Q000453:epidemiology / Q000821:virology; D051379:Mice; D010641:Phenotype; D011135:Polysaccharides, Bacterial; D015995:Prevalence; D012703:Serotyping; D013624:Taiwan / Q000453:epidemiology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D014783:Viscosity
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D006877:Hydroxamic Acids; D011135:Polysaccharides, Bacterial; C512267:RmpA protein, Klebsiella pneumoniae; D037521:Virulence Factors; C036962:capsular polysaccharide K1; C068924:capsular polysaccharide K2; C031819:aerobactin