The role of bacterial virulence factors and Tamm-Horsfall protein in the pathogenesis of Escherichia coli urinary tract infection in infants
V. Israele, A. Darabi and G. H. McCracken Jr
Department of Pediatrics, University of Texas Health Science Center, Dallas.
Forty-three patients and 70 controls were enrolled in an open study to
evaluate the role of bacterial virulence factors and Tamm-Horsfall protein
(THP) in the pathogenesis of urinary tract infection (UTI) due to
Escherichia coli. The ages of the patients and controls ranged from 5 days
to 6 months. Nine patients had upper UTIs and 33 patients had lower UTIs,
based on bacteremia and radiographic evidence. There were no differences
between patients and controls in the percentages of strains showing
hemolytic activity of E coli strains isolated from periurethral and rectal
cultures. Urinary E coli strains recovered from patients showed a
significantly higher percentage of mannose-resistant hemagglutination,
greater P and X fimbriation, more type 1 pili, and the presence of
mannose-sensitive and mannose-resistant hemagglutination when compared with
E coli strains recovered from the controls. The O but not the K
pyelonephritogenic serotypes were more commonly recovered from patients
than from controls. The mean THP concentrations in urine (micrograms of THP
per milligrams of creatinine) were 29.9 and 91.4 micrograms/mg for patients
and controls, respectively. With the exception of hemagglutination
properties and certain pyelonephritogenic O serotypes, other virulence
factors of E coli could not be defined in our infant population. The role
of THP, if any, in the pathogenesis of UTI remains unresolved.