The growth and death of wound bacteria in serum, exudate and slough

Abstract

Six strains of Str. pyogenes and four strains of Staph. aureus were found to grow well from large or small inocula in fresh human serum; four strains of E. coli failed to grow from large inocula and were killed when the inocula were small. Ps. pyocyanea , Proteus and Str. viridans sometimes grew and sometimes failed to grow in fresh serum. In serum which had been treated with trypsin or heated at 56° C. for 1 hr. the Gram-negative bacilli grew readily, and growth was still better in serum which had been heated and then trypsinized. Heating at 56° C. and treatment with proteolytic enzymes were shown to destroy complement and to inactivate the bactericidal activity of fresh serum against a Shigella highly sensitive to the properdin system. It is suggested that these changes might be enough to explain the conversion of serum by proteolytic enzymes into a suitable medium for the growth of coliform bacilli. This change might be brought about by bacterial or leucocytic enzymes. Fibrinolytic serum from a cadaver was found to retain at least a part of its complement and bactericidal activity. Strains of E. coli, Ps. pyocyanea , Proteus, Staph. aureus and Str. pyogenes were tested for growth in burn slough suspension and blister fluid. In slough suspension all strains grew well, but the Gram-negative bacilli grew rather more vigorously than the Gram-positive cocci. In blister fluid E. coli was killed and other strains grew. These findings are discussed in relation to wound sepsis.