Lack of association between hemolysin production and acute inflammation in human urinary tract infection

Hemolysins are cytolytic proteins which have been extensively characterized at the molecular level, however, their in vivo functions remain unclear. This study analyzed the association of hemolysin production with the inflammatory response in patients with urinary tract infection (UTI). Infants and children with their first episode of UTI (n = 644) were followed prospectively. The body temperature, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), urinary leucocyte count and renal concentrating capacity were used as measures of the inflammatory response. The hemolytic genotype (hly) of the Escherichia coli strain from each UTI episode was defined by DNA-DNA hybridization, and the phenotype by hemolysis in blood agar. There was no significant increase in the level of fever, CRP, ESR, or decrease in renal concentrating capacity during UTI episodes caused by hly positive compared to hly negative E. coli. Multiple regression analysis did not demonstrate significant associations of hly with elevated fever, CRP, ESR or reduced renal concentrating capacity. In contrast, patients infected with P fimbriated E. coli strains had higher fever, CRP, ESR and lower renal concentrating capacity than those infected with other strains. This association was not influenced by the hly genotype of the P fimbriated strains. The frequency of hly+ strains was not significantly higher in the subset of patients assigned a diagnosis of acute pyelonephritis compared to asymptomatic bacteriuria. This was in contrast to P fimbriae, which were accumulated in acute pyelonephritis. The results suggested that the acute inflammatory response to E. coli UTI is independent of hemolysin production. The inflammatogenic potential of uropathogenic E. coli clones was better described by the presence or absence of P-fimbriae than by hemolysin.