Characterisation of Escherichia coli adhesins in patients with symptomatic urinary tract infections

Abstract

The ability of bacteria to adhere to the epithelial cells of hosts has been shown to be mediated by adhesins. Many of these show readily demonstrable haemagglutinating activity. Of 109 Escherichia coli strains isolated from patients with symptomatic urinary tract infection, 11 (10.1%) were identified by their haemagglutinating properties as being P fimbriated, which was confirmed by the latex bead test. Other classes of adhesins, termed X and "other", were found in mannose resistant haemagglutinating E coli strains, which represented 4.6% (5) and 0.9% (1), respectively, of all the strains. Type 1 fimbriae were found in 40.4% (44/109) of E coli strains grown on colonising factor agar (CFA) medium. This incidence was 12.8% higher (53.2%, 58/109) when the strains were grown on CFA supplemented with urea, which suggested that urea may modulate the expression of type 1 fimbriae. Conversely, this phenomenon was not seen in P fimbriated E coli. Assays using trypsinised and non-trypsinised human erythrocytes showed no difference in the percentage of strains that haemagglutinated. Regarding the clinical correlation of fimbriated E coli strains, the X mannose resistant haemagglutinating adhesins were also found to be of clinical relevance. P fimbriated E coli strains were isolated from five out of the eight patients with pyelonephritis.