Effects of physiologic variations in temperature on the rate of antibiotic-induced bacterial killing.

The effects of physiologic temperature variations on antibiotic-induced killing of Escherichia coli, Pseudomonas aeruginosa, Streptococcus faecalis, and Streptococcus pneumoniae were studied. At concentrations less than or equal to four times the minimal bactericidal concentration, the activity of each of the antibiotics (gentamicin sulfate, sodium ampicillin, and chloramphenicol) against the test bacteria was influenced by changes in temperature. Only with S. pneumoniae did such influence appear to result directly from temperature-induced changes in the multiplication rate of the bacteria. Repeated subculturing of bacteria at 41 degrees C to induce temperature adaptation had a variable effect on the rate of bacterial killing by appropriate antibiotics. The magnitude of the effect of temperature on antibiotic-induced rates of bacterial killing varies with the antibiotic class, the species of bacteria, and the temperature to which bacteria have been adapted.