CXCL8 and infection: One strain was found whose TnPZ contributed to the vigor of bacterial colonization in a short-term mouse infection model, whereas its tfs3 cluster seemed to diminish fitness (PeCan18B); and another strain was found whose TnPZ stimulated transcription of the IL-8 cytokine genes in cell culture but did not affect fitness in equivalent mouse infections (HUP-B43).