Schistosoma-associated Salmonella resist antibiotics via specific fimbrial attachments to the flatworm.

BACKGROUND: Schistosomes are parasitic helminths that infect humans through dermo-invasion while in contaminated water. Salmonella are also a common water-borne human pathogen that infects the gastrointestinal tract via the oral route. Both pathogens eventually enter the systemic circulation as part of their respective disease processes. Concurrent Schistosoma-Salmonella infections are common and are complicated by the bacteria adhering to adult schistosomes present in the mesenteric vasculature. This interaction provides a refuge in which the bacterium can putatively evade antibiotic therapy and anthelmintic monotherapy can lead to a massive release of occult Salmonella. RESULTS: Using a novel antibiotic protection assay, our results reveal that Schistosoma-associated Salmonella are refractory to eight different antibiotics commonly used to treat salmonellosis. The efficacy of these antibiotics was decreased by a factor of 4 to 16 due to this association. Salmonella binding to schistosomes occurs via a specific fimbrial protein (FimH) present on the surface on the bacterium. This same fimbrial protein confers the ability of Salmonella to bind to mammalian cells. CONCLUSIONS: Salmonella can evade certain antibiotics by binding to Schistosoma. As a result, effective bactericidal concentrations of antibiotics are unfortunately above the achievable therapeutic levels of the drugs in co-infected individuals. Salmonella-Schistosoma binding is analogous to the adherence of Salmonella to cells lining the mammalian intestine. Perturbing this binding is the key to eliminating Salmonella that complicate schistosomiasis.

[Bacterio-parasitic interactions. Enterobacteria and schistosomes (Salmonella - schistosome association)]. / Interactions bactério-parasitaires. Enterobactéries et schistosomidés (salmonello-schistosomo-synusies).

The description of a case imported from Chad of an association of Salmonella typhi - Schistosoma haematobium and, in this connection, a new revised general account. The association Salmonella-Schistomas is wide-spread. It corresponds to a salmonello - schistosomo - micro - association by the fixation of precise bacteria in the case of a bacteriemia on the cutaneous surface of male schistosomes in clearly defined places. These Salmonella constitute a permanent antigenic solicitation and they are capable of mobilization and rejection (bacteriuria after passage through the blood-stream) whereas bacteriosis remains asymptomatic. In fact, on the practical level, a clear and absolute distinction must be made between:--the bacteriemia with the concomitant bacteriuria, which are largely physiological in nature, very frequent and originating from various germs, connected with the emunctory function of the kidneys and which can be observed in any subject.--the schistosomal bacteriuria which are specific entities and evidence of a veritable micro-association of a symbiotic nature between the Salmonella and the schistosome, a micro-association which the bacteriuria reveals unexpectedly whereas the clinical symptoms are absent, not clearly discernible or totally misleading.