Salmonella Suppression by Known Populations of Bacteria in Flies

Abstract

Survivorship of Salmonella typhimurium, Streptococcus faecalis, Proteus mirabilis , and Pseudomonas aeruginosa was studied in dibiotic and tribiotic interactions in vitro and in various regions of the digestive tract of the blow fly, Calliphora vicina . In dibiotic interactions, Salmonella typhimurium dominated Streptococcus faecalis and was dominated by P. mirabilis , but in neither case was it eliminated from the larval gut. In tribiotic interactions, there was synergic suppression and a definite trend toward elimination of Salmonella typhimurium from the gut. This trend approaches but does not match the total exclusion of S. typhimurium from the gut of maggots with a normal flora. Bacterial survival in the gut of the fly is discussed in relation to doubling time, sweep-out rate of the maggot and prepupal gut, and the midgut bactericide.