A new polyvalent Pseudomonas vaccine.

This paper describes the preparation, chemical characterisation and immunogenic properties of a new polyvalent pseudomonas vaccine. New cultural methods were devised which allowed a build-up of the immunogen in the cell wall of the bacteria, and mild extraction techniques were used to remove the immunogens from the cell wall of living bacteria without apparent physical or chemical change which might affect immunogenicity. The polyvalent vaccine comprised 16 component vaccines, each a lipid-protein-carbohydrate complex extracted from one of the 16 different serotypes of Pseudomonas aeruginosa. Single injections into mice of each of the 16 component vaccines induced protection against several strains of homologous serotypes within 3 days of vaccination. The polyvalent vaccine induced similar protection against several strains of each of the 16 serotypes. We would like to thank R. E. Dyster, K. Digby and J. Simmonds for their technical assistance.

Breakpoints in antibiotic sensitivity testing and their clinical relevance.

Antibiotic sensitivity testing has been developed into a highly sophisticated process technically. Interpretation of results obtained requires the definition of breakpoints in order to separate sensitive (likely to respond to treatment) from resistant (likely to persist despite treatment) strains. Various methods used for the setting of breakpoints are described and their merits and drawbacks discussed. Although there may be wide disparities in the definitions adopted in different countries, there is no clinical evidence that favours one set of figures over another. Problems over determination of breakpoints for fungi and of antibiotic combinations remain to be resolved.