Population dynamics of ingested Clostridium difficile in the gastrointestinal tract of the Syrian hamster

The population dynamics of Clostridium difficile in the hamster gastrointestinal tract were studied after intragastric inoculation with organisms and a 51Cr tracer. Seventy-eight percent of spores germinated within the small intestine within 1 hr. Germinated spores and vegetative cells both showed two phases of elimination from the hamster cecum--an initial phase of rapid death that was not affected by antibiotic treatment followed by a phase of complete inhibition of multiplication. The latter phase of inhibition was not seen in antibiotic-treated animals and was thus attributable to the indigenous flora. The 51Cr tracer mixed well with cecal contents and was eliminated exponentially with a dilution rate constant ranging from -0.46/hr to -0.31/hr in normal hamsters. The hamster cecum was therefore dynamically analogous to a continuous flow system, a finding supporting the concept that anaerobic continuous flow cultures are useful in vitro models of the cecal ecosystem.