In assays in which silicone tube implantation and bacterial infection occurred simultaneously, both type 1 and type 3 pili were essential for bladder and catheter colonization, but in assays in which the silicone tube was inserted 24 h before the infection, only mutants lacking at least type 3 pili were significantly impaired in the colonization of both the bladder and implants. The gene discussed is SGCG; the disease is bacterial infectious disease.