Predominance of class II papG allele of Escherichia coli in pyelonephritisin infants with normal urinary tract anatomy

P-fimbrial genotypes of Escherichia coli strains and their possible associa tion with urinary tract abnormalities were studied in infants with pyelonep hritis, A total of 153 urinary E, coli strains were analyzed by polymerase chain reaction for class I, II, and III alleles of the pyelonephritis-assoc iated adhesin gene pap G, Strains with any class II pap G alleles were foun d significantly more often in infants with normal anatomy and function or i n infants with clinically insignificant abnormalities than they were in inf ants with significant abnormalities (90 of 119 vs. 14 of 34 infants; P < .0 01). On the other hand, strains without any papG alleles were found signifi cantly more often in infants with major urinary tract abnormalities (11 of 34 vs. 17 of 119 infants; P = .016), Our genotypic findings indicate that, especially in infants with a normal urinary tract, infection is caused by m ore-virulent E, coli than is present in infants without a normal urinary tr act, This virulence could be due to expression of pyelonephritogenic P fimb riae by an infecting E, coli strain.