PhDProperties of Escherichia coli considered to be of importance
in overcoming host defence mechanisms against urinary tract infection
(OTI) were investigated. These were:
1) 0 and H serotype
2) K antigen content
3) Sensitivity to the bactericidal activity of human serum
4) Haemolysin production
5) Fimbriae production
6) Fermentation of sucrose, salicin and dulcitol
7) Sensitivity to serine, spermine and urea
8) Growth requirements
9) Mucinase production
Ecoli strains isolated from normal subjects and patients
attending the Nephrourological Clinic at St. Bartholomew's Hospital
because of known or suspected UTI, were studied.
Strains isolated from urines more frequently belonged to
0 serogroups 2,4,6,8,18ab and 75, had high K antigen titres, were
haemolytic and fimbriate, and fermented salicin than periurethral
strains from normal subjects. These findings support the concept of
"special pathogenicity", that certain strains are more invasive for
the urinary tract than others. Strains rich in these "pathogenic
properties" were rarely isolated from normal subjects but were
significantly more frequently isolated from periurethral swabs of
patients. Periurethral strains from symptomatic, abacteriuric
(urethral syndrome) patients were similar to those from bacteriuric
patients when they were between infections. Previous work has not
implicated bacteria in the aetiology of most cases of this disease
and this finding remains unexplained. Strains isolated from the
upper tracts of patients undergoing localisation tests more frequently
exhibited pathogenic properties than those isolated from only the
lower tract, and this was considered to reflect the superior ability
of these strains to reach the upper tract or better combat host
defence mechanisms
