Automation of Salmonella typhi phage typing.

Two steps in the procedure for bacteriophage typing of Salmonella typhi have been automated. The culture inoculum was applied by flooding the surface of phage agar in a 150x20 mm petri dish and removing the excess liquid with a safety pipettor. This step replaced the older method of manually preparing up to 100 individual areas for inoculation. The number of bacteria per unit area was the same with both methods, so the automated method involved no change in the technique. The second automated step involved use of a bacteriophage applicator which simultaneously dispensed 59 uniform drops of bacteriophages onto the inoculated plate. The automated procedure has reduced personnel time by about 90% with no less in sensitivity or accuracy.