BIOTYPING OF ESCHERICHIA-COLI IN MICROWELL PLATES

A simple, inexpensive scheme of eight tests for biotyping strains of E scherichia coli in microwell plates is described. The tests comprise p rimary tests for the fermentation of raffinose, sorbose, ornithine, du lcitol and 2-deoxy-D-ribose, and secondary tests for rhamnose fermenta tion, lysine decarboxylation and motility. Among a collection of 75 cl inical isolates of Esch. coli from 12 patients, 18 full biotypes desig nated according to their positive and negative reactions in the eight tests were distinguished. These biotypes gave an indication of the nat ural history of patients' infections. Because it provides excellent an d reliable type discrimination, biotyping can be used in combination w ith other typing techniques to resolve local epidemiological problems involving Esch. coli.