Factors affecting the microecology of the gut

Abstract

This author began his career in medical bacteriology in the early 1950s, i.e. shortly after the introduction of antibiotics into clinical practice. In those years the often similar side-effects of these chemically different drugs were usually (and correctly) attributed to population shifts among the indigenous microflora with a resulting overgrowth or superinfection by undesirable or outright pathogenic microorganisms. Early experimental data included the demonstration that oral administration of streptomycin rendered guinea-pigs susceptible to enteric infection with cholera vibrios (Freter, 1954, 1955) and made mice susceptible to colonization by cholera vibrios or shigellae (Freter, 1956a). The most exciting event at the time seemed to be the discovery that colonization of streptomycin-treated animals by these human pathogens could be completely prevented by the feeding of a streptomycin-resistant strain of Escheriehia coli (Freter, 1956a). This raised the (then) justifiable expectation that the oral administration of a properly selected strain of E. coli or other bacterial species would allow it to colonize the gut and take over some or all of the normal functions of an indigenous microflora, when the laUer had been disturbed by antibiotics or by other forms of stress.