ABSTRACT
Objective To study adhesion and invasion of adherent-invasive Escherichia coli strains and its ability of survival and proliferation in macrophage cells.Methods Bacteria from the mucosa tissues of ileum,colon and rectum of inflammatory bowel disease (IBD)patients were isolated,cultured and identified.The toxic genes were confirmed by polymerase chain reaction.The adhesion and invasion ability of bacteria and its survival and proliferation ability in macrophage cells were observed after co-culture with cells.Results Five adherent-invasive Escherichia coli strains were isolated from the intestinal mucosa specimens of two patients with Crohn′s disease and one patient with ulcerative colitis.The adhesion rates of five bacteria stains (2A,2B,15A,15B,19B)to Caco-2 cells were (1 .4 ± 1 .3 )%,(1 .5 ± 0.6 )%, (0.6±0.1)%,(1 .4±0.4)% and (1 .1 ±0.8)%,respectively.The adhesion rates to Int-407 cells were (1 .0±0.8)%,(1 .5 ±0.8)%,(1 .0 ±0.8 )%,(1 .0 ±0.8 )% and (0.3 ±0.0 )%,respectively.The invasion rates to Hep-2 cells were (10.1 ±7.0)%,(0.7 ±0.4)%,(0.4 ±0.3 )%,(2.2 ±1 .0)% and (2.1 ±1 .8)%,respectively.The invasion rates to Int-407 cells were (0.7 ±0.5 )%,(0.5 ±0.3 )%, (2.8±1 .2 )%,(0.7 ±0.5 )% and (0.5 ±0.4)%,respectively.All five adherent-invasive Escherichia coli strains could survive and proliferate in macrophage cells.Conclusions Five adherent-invasive Escherichia coli strains are isolated for the first time in Chinese patients with IBD,and all of them could survive and proliferate in macrophage cells.