Datta S, Pal A, Basu S, Banerjee P C
Indian Institute of Chemical Biology, Calcutta, India.
Microb Drug Resist. 1997 Winter;3(4):351-7. doi: 10.1089/mdr.1997.3.351.
The present work characterizes a 70 kb plasmid of the Indian epidemic isolate Shigella dysenteriae type 1 strain Dt66 in relation to virulence and drug-resistance characters. Curing of the plasmids of Dt66 strain by acriflavine (AF) yielded seven groups of AF-cured derivatives. One group of derivatives containing 5 plasmids (70-2.5 kb) as against 6 (120-2.5 kb) in the wild type showed resistance to chloramphenicol, pivmecillinam, streptomycin, and tetracycline (CmrPivrSmrTcr) but sensitivity for ampicillin and nalidixic acid (AmsNals). This derivative when used as donor in conjugation experiments with a plasmidless E. coli KL318 strain (AmsCmsPivsSmrTcsNalr) as recipient, transferred only its 70 kb plasmid into the recipient with concomitant transfer of the CmrPivr phenotype. Both the donor and the transconjugant exhibited a diffuse pattern of adherence and produced keratoconjunctivitis in guinea pigs. Transconjugants contained a 42 kDa lipopolysaccharide band which was absent in recipient. Moreover, both donor and transconjugants showed Congo red binding ability. The results suggest that the 70 kb plasmid of S. dysenteriae Dt66 strain encodes not only Cmr,Pivr character but also is associated with virulence-related characters such as Congo red binding, LPS-biosynthesis, HeLa cell adherence, and keratoconjunctivitis related to virulence.
本研究对印度流行分离株痢疾志贺氏菌1型菌株Dt66的一个70 kb质粒的毒力和耐药特性进行了表征。用吖啶黄素（AF）消除Dt66菌株的质粒产生了七组AF消除衍生物。一组衍生物含有5个质粒（70 - 2.5 kb），而野生型含有6个质粒（120 - 2.5 kb），该组衍生物对氯霉素、匹美西林、链霉素和四环素具有抗性（CmrPivrSmrTcr），但对氨苄青霉素和萘啶酸敏感（AmsNals）。该衍生物在与无质粒的大肠杆菌KL318菌株（AmsCmsPivsSmrTcsNalr）作为受体进行的接合实验中用作供体时，仅将其70 kb质粒转移到受体中，并伴随CmrPivr表型的转移。供体和转接合子均表现出弥散性黏附模式，并在豚鼠中引起角膜结膜炎。转接合子含有一条42 kDa的脂多糖带，而受体中不存在。此外，供体和转接合子均显示出刚果红结合能力。结果表明，痢疾志贺氏菌Dt66菌株的70 kb质粒不仅编码Cmr、Pivr特性，还与毒力相关特性有关，如刚果红结合、LPS生物合成、HeLa细胞黏附以及与毒力相关的角膜结膜炎。
