Bacterial vaccines are suspensions of the killed bacteria in physiologic salt solution. Cresol is usually added as a preservative.

The use of many of these vaccines is in the experimental stage. They are often prepared from cultures obtained from the individual to be treated (autogenous vaccines) ; these usually give the best results, and some authors maintain that "stock" vaccines should be used only when it is impracticable to secure the autogenous agent. Bacterial vaccines are used to secure the production of an active immunity. Great care and skill are necessary for their proper use, and no definite statements as to dosage, etc., can be given.

Vaccine Virus.

See Under Virus Vaccinum.