The Journal of Medical Microbiology, Vol 10, Issue 3 293-298, Copyright © 1977 by Society for General Microbiology
Biochemical typing of urinary Escherichia coli strains by means of the API 20 E enterobacteriaceae system
B. I. Davies
With the API 20 E Enterobacteriaceae system of biochemical testing, a
biotype, coded numerically, was determined for each of 574 strains of
Escherichia coli isolated from patients with urinary tract infection. The
serotypes of the strains were also determined. Fifty-five different
biotypes were identified, two accounting together for 42% of the strains
examined and seven others each accounting for between 8.4 and 1.9%. There
was little correlation between biotype and serotype. Fifty pairs of strains
were isolated from patients before treatment. In 43 the biotype and
serotype of both strains of each pair were the same. In six pairs the
biotype, but not the serotypes, differed, the difference being limited to
the results of the tests for lysine decarboxylase. The biotypes of the
strains of the remaining pair differed widely although their serotypes were
the same. It is suggested that this method of biotyping offers a simple but
accurate way of discriminating between recrudescent urinary tract infection
caused by E. coli and that due to reinfection.
