The prc mutant of E. coli RS218 exhibited a decreased ability to cause a high level of bacteremia [24] [as confirmed by us in four species (Tables 3 and 4)] and is more susceptible to human serum killing than strain E. coli RS218 as are the strains in this study (Fig 3 and S2 Table). The gene discussed is PPRC1; the disease is bacterial infectious disease with sepsis.