Interestingly, we noticed that genes related to foc fimbriae (focD, focH), trp biosynthesis (trpA, trpB, trpD), and RNA helicases (hrpA, deaD) had previously been identified as putative fitness factors in a transposon mutagenesis-based foreword genetic screen of UPEC BSI, but not UTI (20, 28). This evidence concerns the gene TPSG1 and bathing suit ichthyosis.