[Microcalorimetric testing of the antibacterial activity of doxycycline, gentamicin and their combination (author's transl)].

The antibacterial activity of doxycycline and gentamicin was tested by microcalorimetric methods and by finding out the MIC of these substances, the test organisms being Staph. aur. haem. (13.665) and E. coli (3.579). The investigations were carried out with the above mentioned substances both alone and in combination. A synergistic effect was found with both methods applied, but microcalorimetry showed that the combination influences the cell metabolism in another way than the individual substances. Another remarkable finding is that doxycycline inhibits the microcalorimetric activity of our bacterial strains in doses 10 to 100 times lower than found with the standard MIC finding methods.