Pb. Crichton et al., A MINIATURIZED BIOTYPING SYSTEM FOR STRAIN DISCRIMINATION IN ESCHERICHIA-COLI, Epidemiology and infection, 111(1), 1993, pp. 81-88
A two-tier miniaturized scheme of eight tests was devised for biotypin
g strains of Escherichia coli in microwell plates. Primary biotypes we
re defined by positive and negative reactions in tests for fermentatio
n of raffinose, sorbose, dulcitol and 2-deoxy-D-ribose and for decarbo
xylation of ornithine when read after specified periods of incubation;
subtypes were identified within primary biotypes according to results
in secondary tests for rhamnose fermentation, lysine decarboxylation
and motility. The method gave reproducible results on different occasi
ons of testing. Among 100 E. coli strains from various sources, 26 of
the 32 possible primary biotypes and 56 full biotypes, as defined by r
esults in both primary and secondary tests, were identified, thus demo
nstrating a high index of strain discrimination (D = 0.98). The scheme
is recommended as a simple, reliable, inexpensive and efficient metho
d of differentiating strains of E. coli.