Abstract
Helicobacter pylori is a Gram-negative microaerophilic bacterium which colonizes the gastric mucosa of human stomach. Infection of H. pylori is found to link to gastric gastritis, gastric ulcer, duodenal ulcer and gastric cancer. H. pylori is recently reported to produce biofilms coated in the outside of cell wall. Biofilm, in addition to as a natural defense barrier, may also play a role in pathogenesis in some bacteria including Pseudomonas aeruginosa and Streptococcus mutans. Formation of biofilm is regulated by quorum sensing system. The first part of this study is to investigate the morphology of H. pylori biofim at various stages by using scanning electronic microscope and confocal laser scanning microscope including adherence to surface, microcolony formation and aggregated cell to produce biofilm material. The aggregated biofilm conducted some pore and channel structures and the average thickness of the mature biofim was about 70~80μm. The second part of this study is to find out the relationship between LuxS protein and biofilm formation. Isogenic luxS - mutation was generated. Despite no apparent difference in bacterial morphology, the luxS- mutant affects bacteria growth and biofilm formation, suggesting its function in H. pylori growth and biofilm formation. Finally, the relationship between biofilm formation and antibiotic resistance of clinical isolates was investigated. A positive relationship was found between the masses of biofilm and the resistance of antibiotics penetration. In addition, resistant isolates were found to have a higher degree of biofilm formation (p=0.028). We concluded that H. pylori produced biofilm that acts as a barrier to avoid the antibiotics effects and that the Lux protein is involved in biofilm formation.