Use of a Laser-Doppler electrophoresis method in bacteriology (preliminary results)

A new electrophoresis system using Laser Doppler velocimetry has been developed. This technic allows fast measurements (1 minute) over a large number of particles (several thousand or more). Furthermore, the small size of the particles is no longer a limitation of the measurement. These qualities made it possible to study the electrokinetic properties of cells. In this paper the authors present the first application obtained on different types of bacteria (Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris) submitted to five antibiotics (gentamycin, minocyclin, cephalotin, spiramycin, sobramycin). After four hours or incubation at 37°C, important decreases of electrophoretic mobility were observed on bacteria treated with antibiotics to which they were sensitive. On the other hand, no significant modification appeared on bacteria treated with antibiotics to which they were not sensitive. In conclusion, the electrophoretic mobility test seems to be useful to study the response of bacteria to antibiotics and perhaps could be used to set antibiograms.