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METHIONINE UPTAKE AND CYTOPATHOGENICITY OF VIABLE BUT NONCULTURABLE SHIGELLA DYSENTERIAE TYPE 1
Citation:
Rahman, I., R. Colwell, M. Shahamat, P. Kirchman, E., AND Russek-Cohen. METHIONINE UPTAKE AND CYTOPATHOGENICITY OF VIABLE BUT NONCULTURABLE SHIGELLA DYSENTERIAE TYPE 1. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/005, 1994.
Description:
A pathogenic strain of Shigella dysenteriae Type 1 was selected for study to elucidate the physiology and potential pathogenicity of organisms In the viable but nonculturable (VBNC) state In the environment. tudies in our laboratory have shown that S. dysenteriae Type 1 survives in laboratory microcosms in the VBNC state for long periods of time, i.e., more than 6 months. BNC cells of S. dysenteriae Type 1 were found to retain cytopathogenicity for cultured HeLa cells. o determine whether VBNC S. dysenteriae Type 1 (expressed protein after loss of culturability, S-labeled methionine was added to suspensions of VBNC cells. otal cellular proteins were extracted and examined by autoradiography. esults Indicate that VBNC S. dysenteriae Type I Is capable of both active uptake of methionine and incorporation of methionine into protein. mino acid uptake and protein synthesis substantiate the viability of cells of S, dysenteriae Type I in the VBNC state, i.e., although the cells are unable to be cultured on laboratory media by standard bacteriological methods, the cells remain metabolically active. urthermore, VBNC cells of S. dysenteriae Type 1 may pose a potential public health hazard that has not yet been recognized.