Abstract
The variation in metabolism of biochemical test substrates by klebsiella isolates has been demonstrated. It is suggested that this variation is likely to result in false-negative reactions in biochemical tests incubated for short periods. The observations made may explain the reported difficulties in obtaining reproducible results in biotyping Klebsiella strains. Preliminary work suggests that differences in substrate metabolism will provide a means of increasing the sensitivity of methods for the biochemical typing of Klebsiella spp.