Frequency and organization of pap homologous DNA in relation to clinical origin of uropathogenic Escherichia coli

Abstract

The pap operon encodes the gal alpha 1-4gal beta specific adhesins of Escherichia coli. The presence and organization of pap homologous DNA was determined using two probes specific for pap in 217 uropathogenic E. coli samples by dot blot and Southern blot analysis. The frequency of pap homologous DNA was 76% in pyelonephritis, 69% in cystitis, and 52% in an asymptomatic bacteriuria group. Further, the gal alpha 1-4gal beta binding phenotype among the pap-positive strains was expressed more often in acute pyelonephritis (91%) than the cystitis (60%) or asymptomatic bacteriuria (52%) strains. This was explained in part by difference in organization of pap homologous DNA between the genotypically positive pyelonephritis and asymptomatic bacteriuria strains. The pyelonephritis isolates contained three copies of pap significantly more often than the asymptomatic bacteriuria strains, and the pyelonephritogenic O-antigen types had a general increase in pap copy number. The difference in expression of gal alpha 1-4gal beta adhesins between pyelonephritis and asymptomatic bacteriuria isolates was thus not only a function of the frequency of pap homologous DNA but also of phenotypic expression among genotypically pap-positive strains.