Association of Resistance to Bile Salts and Virulence in Salmonella typhimurium Strains

Abstract

A strain of Salmonella typhimurium unable to form colonies on Difco SS agar, which contains 0.85% Bacto Bile Salts No. 3, was less virulent when inoculated intraperitoneally into white Swiss mice than were 3 mutant strains not inhibited under the same conditions. A sensitive reversion from one of the resistant mutants exhibited a virulence pattern similar to that of the sensitive parent strain. Resistant bacteria produced greater damage to internal organs and were able to persist for longer periods of time in host animals although the incidence of fatal infection was only somewhat higher than in animals infected with bile sensitive organisms. These observations indicated that salmonellae able to withstand the effect of high concentrations of bile salts were also better able to establish chronic infection in mice leaving relatively large numbers of survivors as carriers of the organism.