Considering that heat-inactivated ExPEC did not induce macrophage apoptosis in vitro (Rodrigues et al., 1999), but virulent ExPEC caused severe damage to macrophages (Zhuge et al., 2019), it is very likely that COX-2 up-regulation during ExPEC XM O2:K1:H7 infection may inhibit the apoptosis of macrophages to enhance the human immune system. Here, PTGS2 is linked to infection.