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Antimicrob Agents Chemother. 1973 July; 4(1): 62-65
Copyright © 1973 American Society for Microbiology. All Rights Reserved.

Scanning Electron Microscopy of the H37Ra Strain of Mycobacterium tuberculosis Exposed to Isoniazid

Kuni Takayama, Lynn Wang¹ and Richard S. Merkal

Veterans Administration Hospital, Madison, Wisconsin 53705
Institute for Enzyme Research, University of Wisconsin, Madison, Wisconsin 53706
Agricultural Research Service, National Animal Disease Laboratory, Ames, Iowa 50010

ABSTRACT

The morphology of cells of the H37Ra strain of Mycobacterium tuberculosis exposed to 0.5 µg of isonicotinic acid hydrazide (isoniazid) per ml was examined by scanning electron microscopy (SEM). Cells that were exposed to isoniazid for 3 h showed no detectable change, whereas cells exposed to the drug for 24 h exhibited diverse morphological features. From our examination of these SEM pictures, we have reconstructed the probable sequence of morphological changes to be as follows: (i) the wrinkling of the cell surface was ascribed as the earliest observable change, (ii) the cell surface then became very rough and ragged, (iii) eventually the cytoplasmic material was extruded from the cell, (iv) this event produced a collapsed cell, (v) the cells began to fragment, (vi) the fragmented cells then coalesced to form an amorphous mass of cell debris.

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FOOTNOTES

¹ Present address: Department of Bacteriology, Hadassah Medical School, The Hebrew University, Jerusalem, Israel.

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Antimicrob Agents Chemother. 1973 July; 4(1): 62-65
Copyright © 1973 American Society for Microbiology. All Rights Reserved.

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