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    Please use this identifier to cite or link to this item: http://ir.cnu.edu.tw/handle/310902800/29716

    標題: Low prevalence of rmpA and high tendency of rmpA mutation correspond to low virulence of extended spectrum beta-lactamase-producing klebsiella pneumoniae isolates
    作者: Yu, Wen-Liang
    Lee, Mei-Feng
    Tang, Hung-Jen
    Chang, Ming-Chung
    Chuang, Yin-Ching
    貢獻者: 保健營養系
    關鍵字: ESBL hypermucoviscosity
    klebsiella pneumoniae
    rmpA gene
    spontaneous mutation
    日期: 2015-02
    上傳時間: 2016-04-19 19:05:41 (UTC+8)
    出版者: Taylor & Francis Inc
    摘要: Invasive syndrome caused by Klebsiella pneumoniae (KP), including liver abscess, is mainly caused by community-acquired strains with characteristics of positive hypermucoviscosity (HV) phenotype and regulator of mucoid phenotype A (rmpA) and transcriptional activator (rmpA2) genes. Extended- spectrum -lactamase-producing KP (ESBL-KP) is commonly nosocomial and rarely HV-positive. We aimed to explore the reasons of the rarer prevalence of HV phenotype, rmpA and rmpA2 as well as the virulence phenotype among the ESBL-KP isolates from clinical specimens than those non-ESBL isolates. The -lactamase genes, rmpA, rmpA2 and genes for K capsule serotype of 440 KP isolates were analyzed. The virulence of the isolates was characterized by the mouse lethality experiments. The prevalence rates of HV phenotype (similar to 50% vs. < 10%) as well as rmpA and rmpA2 genes (similar to 50-60% vs. < 20-30%) were significantly higher in non-ESBL group than in the ESBL group (p < 0.0001). Expression of HV phenotype in the rmpA-positive KP isolates was significantly rarer in the ESBL group than in non-ESBL group (33.3% vs. 91.9%, p < 0.0001). The frameshift mutations of rmpA and/or rmpA2 corresponded to negative HV phenotype of KP isolates that harbored the rmpA and/or rmpA2, resulting in variable mouse lethality (LD50, similar to 10(3) - >5 x 10(7) CFU). The mutation rates might significantly differ among KP isolates from various sources. Virulence was dependent on rmpA-related HV phenotype. In conclusion, ESBL-KP isolates were less hypermucoviscous and less virulent than non-ESBL KP isolates, mostly due to concurrently lower carriage and higher mutation rates of the rmpA and rmpA2 genes.
    關聯: Virulence, v.6 n.2, pp.162-172
    Appears in Collections:[保健營養系(所) ] 期刊論文

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