Table 3. Intramacrophage survival properties of strains C50041 and ΔspiA.

Values are mean±sd.

Strain	Growth phase	Percentage invasion (3 h)	Percentage proliferation (23 h)	Proliferation ratio (23 h/3 h)
C50041	Exponential	1.43±0.25	35±7.1	24.5±0.71
ΔspiA		1.15±0.21	34±4.9	29.23±1.09
C50041	Biofilm	29±3.5	1273±3.22	44.29±5.8*
ΔspiA		46±6	1140±3.39	24.7±3.98

^*The proliferation rate of strain C50041 was significantly greater than that of ΔspiA in the biofilm phase (P<0.05).