Mode of action of chloramphenicol. VII. Growth and multiplication of Escherichia coli in the presence of chloramphenicol.

Allison, James L. (Walter Reed Army Institute of Research, Washington, D. C.), Richard E. Hartman, Roberta S. Hartman, Alan D. Wolfe, Jennie Ciak, and Fred E. Hahn. Mode of action of chloramphenicol. VII. Growth and multiplication of Escherichia coli in the presence of chloramphenicol. J. Bacteriol. 83:609-615. 1962.-Significant increases in both total and viable numbers of bacteria in cultures of Escherichia coli B/r were shown to occur in the presence of "bacteriostatic concentrations" (50 mug/ml) of chloramphenicol. Bacterial viability began to decline between one and two generation times after the addition of the antibiotic. It is inferred that unbalanced growth and cellular division occurring in the absence of protein synthesis give rise to physiologically inhomogeneous bacterial populations. Analytical studies on such populations, therefore, do not necessarily determine events that are typical for all individual bacteria in the culture. These considerations emphasize further the need for elucidating the primary action of chloramphenicol in isolated, cell-free systems that are free of physiological complications.