Current approaches to the classification, characterisation and typing of pathogenic anaerobic bacteria.

Characterisation systems based on the demonstration of soluble antigens and toxins are of much practical value but have clear taxonomic limitations. This is illustrated by reference to our work with some of the pathogenic clostridia. The definition and classification of the anaerobic cocci is a difficult and continuing challenge. Systems for the classification and characterisation of the gram-negative non-sporing anaerobic bacilli are evolving well, though there are still some very difficult areas. A selection of the most helpful tests is indicated. Biotyping systems are compared with serotyping systems; the results of serological approaches to characterisation are encouraging. The further exploration of bacteriocin typing seems to be merited. The challenge of characterisation and classification of anaerobic spirochaetes commonly involved in human infections must now be taken up.