Interaction of salmonellae and schistosomes in hostparasite relations

Abstract

Salmonella paratyphi A were cultured from the tegument of Schistosoma mansoni after the worms were filtered from 2 patients with naturally occurring chronic Salmonella paratyphi A infection. Examination by immunofluorescence microscopy of the S. mansoni revealed S. paratyphi A colonies on and within the surface tissues of the schistosomes. To further define and establish this relationship a series of laboratory experiments were conducted and subsequently S. paratyphi A were also cultured from the tegument of schistosomes (1) after the bacteria were incubated with the S. mansoni in vitro; and (2) following recovery of the worms from mice previously inoculated with the salmonella. In addition, in the presence of S. mansoni, S. paratyphi A was shown to be protected from the bactericidal effects of ampicillin in vitro. This bacteria-host-parasite interaction may in part explain why Salmonella paratyphi A infection and schistosomiasis clinically occur frequently together and present such a difficult therapeutic problem.