STX2 and pyelonephritis: Among the 16 virulence genes which represent the main categories of virulence determinants (sfa, papC, sepA, etrA, aer, feaG, fsaA, eaeA, rfc, cnf1, hlyA, eltA, estA, exhA, stx1, and stx2), we only detected the papC gene in 10 E. coli, which encode the protein of pilus associated with pyelonephritis and belong to ExPEC.