| 摘要: | 中文摘要 大腸桿菌莢膜多醣類對菌株之抗
生素感受性及病原性的關係 以Cefazloin (CEF ) 誘導非莢膜多
醣類產生株 ( Non-capsular polysaccharide-synthesizing strains )
之產生莢膜多醣類變異株 ( CEF-CPS ) 及其莢膜多醣類(CPS)等來探討菌
株之莢膜多醣類產生能力與抗生素感受性及病原性的關係及其莢膜多醣類
對菌株生物活性之影響,其結果如下: (1)母株對小白鼠的腹腔致 死劑
量其LD50是33.2mg/Kg而變異株是12.0mg/Kg.母株和CPS同時或經CPS予處
理小白鼠腹腔注射後兩者都會處促使母株對小白鼠之致死能力明顯增加而
具劑量關係.(2).對天竺鼠紅血球凝集反應力價.受培養基種類的影響,即
培養基誘導菌株產生CPS與否會影響其凝集力價,若添加CPS時亦會處促使
母株之血球凝集力價之增加.(3).In vitro and in vivi 變異株對抗巨噬
細胞能力明顯高於母株;CPS預處理小白鼠其腹腔細胞會增加細菌抗吞噬能
力,而且其作用則隨劑量增加而加強. (4).變異株較母株對多種抗生素具
較高之耐性限閾,且當細菌懸浮液和CPS同時存在時會增加菌株對抗生素之
吸附能力及耐性.(5).試管內CPS短期處理macrophages會活化細胞對細菌
的吞噬作用及tetra-zolium 的還原能力, 但長期處理時會抑制
macrophages對tetrazolium的還原能力,同時發現macrophages會明顯增加
lactate dehydrogenase (LDH)的釋放. 故由以上結果顯示大腸桿
菌莢膜多醣類產生能力與菌株對抗生素之感受性,對抗巨噬細胞吞噬能力
及對小白鼠的致死能力等具相當密切相關性. Key word: capsular
polysaccharide, mouse lethality, hemagglutination,
phagocytosis, antibiotic susceptibility.
Summary The effect on
capsular polysaccharide synthesis of Escherichia coli
on its antibiotic susceptibility and pathogenicity.
By using cefazolin induction in proteose-peptone glycerine salt
medium,we screened a capsular polysaccharide-synthesizing
variant from a noncapsular polysaccharide synthesizing parental
strain of Escherichia coli.We used this E. coli variant strain
and the purified capsular polysaccharide synthesis on its
antibiotic susceptibility and pathogenicity. Theresults were
summarized as: (1) The LD50 of parental strain on ICR female
micewas 33.2 mg/kg ( the wet of E. coli/the body weight of mouse
),whereas theLD50 of variant strain was reduced to 12.0 mg/kg.
However, if we pretreated the ICR mice with purified capsular
polysaccharide and then intraperitoneal injection of parental
strain 1h later, or challenged with the mixture of capsular
polysaccharide and parental strain, the mouse lethality of
parental strain wouldbe enhanced and it had a dose dependent
curve. (2).The hemagglutination titeof E. coli with Guinea pig
RBC were influence by the bacterial culture media.wefound that
the culture media might induced E.coli to synthesize capsular
polysa-ccharide and the changed the HA titers. Mixing the
purified capsular polysaccharide with the parental strain would
also increase its HA titer. (3).The antiph-agocytic activity of
variant strain was much higher than that of the parental strain.
Purified capsular polysaccharide could enhance the
antiphagocytic activi-ty of parental strain, and it also had a
dose dependant phenomenon. (4). The resistance threshold of
variant strain to many different antibioticswere higher than
that of the parental strain.The presenceof capsular
polysaccharide might trap the antibiotics, so that it would
increase the antibiotic resistance of parental strain, and
(5). After treating the macrophages with purified capsular
polysaccharide in vitro,the activities of phagocytosis and
tetra-zolium reduction were enhanced in early incubation period.
However, inhibitionmay be observed after long time treatment
with purified capsular polysaccharide,while concomitantly
increased of Lactate dehydrogenase activity in culture sup-
ernatant. Based on the above results, we demonstrated that
the capsular polysaccharide synthesizing ability were closely
related to the antibiotics susceptibility, ant--phagocytic
activity of E.coli and lethality on ICR mice. |
