Although untreated PMNs became apoptotic within 10 h, 40% of infected PMNs could survived up to 24 h post-infection in this study; PMNs infected with K. pneumoniae serotype K1 significantly delayed the constitutive apoptosis of PMNs, detected by morphological analysis, annexin V, DNA fragmentation assay, and Western blot analysis. The gene discussed is ANXA5; the disease is infection.