Factors affecting the value of a simple biochemical scheme for identifying Enterobacteriaceae: the reproducible recognition of biotypes.

Abstract

SUMMARY A biochemical screening scheme on agar media for differentiating Enterobacteriaceae in a hospital laboratory is evaluated. Careful observation of test reactions within the scheme permitted the recognition of 78 biotypic reaction patterns which could contribute to epidemiological surveillance. The limitations of the technique are described and discussed and methods of importance in ensuring the reproducibility of reaction patterns emphasised.

Biotypes of Klebsiella pneumoniae (sensu lato) and Enterobacter aerogenes characterised by differential substrate metabolism: application of the technique.

“…Isolates were identified on the basis of aesculin hydrolysis, citrate utilisation, ornithine decarboxylation, phenylalanine deamination, indole production, H2S production, colony colour on xylose lysine decarboxylase agar, urease production, and motility; biochemical tests were carried out as described by Barr et al (1977).…”

“…MEDIA Cultures were maintained on nutrient agar slopes and streaked on MacConkey agar 24 hours before use. Media for the identification of clinical isolates were prepared as described by Barr et al (1977). Media for the biotyping of clinical isolates by the methods of Rennie and Duncan (1974) were prepared, and biochemical tests carried out, by conventional methods (Cowan, 1974).…”