Overall, infection results of deletion mutants revealed that several mutants had a significant defect only during the competition experiment, including eight mutants during uptake (bcf, csg, stb, CS54, sipF, STY4679, STY4842-43, and STY1869) and 11 mutants defective in survival (exbDB, ompN, rfbIC, stc, STY0041, pagC, sipF, SPI-4, STY1398, typA, and STY1869) (P<0.05) (Figures 2 and 3). Here, STC1 is linked to infection.