Some problems--and their solutions--in the production of DTP (diphtheria, tetanus, pertussis) vaccine.

The desirability of choosing methods and equipment to meet local needs such as yield per cycle and ready availability of components of media and other reagents, and of simple equipment such as good quality glassware, of replacement parts for more complex equipment, and, most of all, of technical assistance is emphasised. Particular emphasis is given to ways of increasing yield from agar and static-liquid culture and to simple methods of separating bacteria from large volumes of culture using bacterial-precipitants. Designs are given for simple growth and mixing vessels, including magnetically-stirred units which require a minimum of servicing. It is strongly recommended that the basic production-unit should be a simple, multipurpose, high-quality stainless-steel vessel of appropriate size: such a unit has a working-life of at least 10 years. Regardless of the type of equipment used, simple or complex, the need, at all times, for well-trained technical staff is also stressed.