IN ALL surgical procedures asepsis is essential, and in preparing for operation on the bowel it would seem desirable to render the lumen as clean as possible.
About 75 per cent of the flora of the normal adult colon consists of gram-negative organisms, mainly enterobacteriaceae, though there are decided differences in the various segments of the gut. The remainder are mainly streptococci, anaerobes and organisms which probably have not regularly been studied in culture. Occasionally exceptional numbers of Proteus, Pseudomonas and even Staphylococcus pyogenes may be present. These appear often to cause pronounced degrees of disfunction, although they are not commonly regarded as gut pathogens in the strict sense. There may, in addition, be true pathogens of the Salmonella or dysentery groups.
Until the introduction of streptomycin by Schatz, Bugie and Waksman1 there had been no antibiotic acting on these gram-negative bacillary organisms. Because of the concentrating effect of