Carbohydrate involvement in the association of a prokaryotic cell with Trichomonas vaginalis and Tritrichomonas foetus.

Previous studies have shown that Trichomonas vaginalis are capable of ingesting bacteria. This observation was confirmed in the present study and extended to Tritrichomonas foetus. Using a special strain of Escherichia coli grown under conditions that produced fimbriae presenting a lectin-like molecule recognizing mannose, we showed that the bacteria attached to and were ingested by trichomonads through a mechanism involving cell-to-cell recognition. Absence of the fimbriae or addition of alpha-methyl-D-mannoside to the interaction medium blocked attachment of the bacteria to the protozoa cell surface. Ingested bacteria were later digested within the cytoplasmic vacuole.