Helicobacter pylori adheres selectively to Fusobacterium spp

Helicobacter pylori strains ATCC 43504 and ATCC 43629 were tested for their ability to coaggregate with 79 strains of bacteria representing 16 genera. All except two of the strains were of human origin, and most of the strains were isolated from the oral cavity. The helicobacters failed to coaggregate with all strains except the fusobacteria. Several coaggregations were partially or completely inhibited by lactose. Strong coaggregation was seen with each of four subspecies of Fusobacterium nucleatum and with Fusobacterium periodonticum ATCC 33693, all of human dental plaque origin. In contrast, the helicobacters failed to coaggregate with non-plaque isolates, Fusobacterium mortiferum ATCC 25557 and Fusobacterium ulcerans ATCC 49185. Heat treatment of the fusobacteria inactivated their ability to coaggregate, whereas heating of the Helicobacter partners had no effect, suggesting the presence of an adhesin on the fusobacteria and a corresponding receptor on the helicobacters. The potential ability of H. pylori to colonize the oral cavity by adhering selectively to the ubiquitous fusobacteria gives credence to the possibility that dental plaque may serve as a reservoir for this pathogen outside of the stomach.