Low urinary counts of P-fimbriated Escherichia coli in presumed acute pyelonephritis.

We report 6 children who showed clinical symptoms and laboratory signs of acute pyelonephritis but in whom bacteriuria was insignificant, with Escherichia coli 10(4)/ml, or less. None of the children had symptoms of other disease. Three of the children who were at first treated inadequately or were not treated with antibiotics developed significant bacteriuria later on (10(5)/ml, or greater). Ultrasonic scanning to evaluate kidney involvement at the acute phase of disease showed transient changes in four of the 6 children--dilatation of one or both pelves or increased ecogenicity of the renal sinus, or both. The urinary E coli strains isolated from all 6 children were P-fimbriated, as determined by a P-fimbriae specific particle agglutination test (PPA test). P-fimbriate E coli are known to be strongly associated with acute non-obstructive pyelonephritis in children and we suggest that the finding of any number of P-fimbriated E coli in the urine of children with clinical evidence of acute pyelonephritis supports this clinical diagnosis.