In the course of our study of established infections during the past year and a half, it has been demonstrated frequently that penicillin is of questionable benefit or no benefit at all in the treatment of many infections in which there is a mixture of organisms. In some of these infections there is undoubtedly a synergistic action on the part of the bacteria in the production of the pathologic process. In other cases, secondary contaminants which are not pathogenic or are only feebly so, under ordinary circumstances, are able to multiply in the presence of wound exudate or dead tissue.
Using the wound as a culture medium, these organisms produce metabolic products which may be toxic locally to the tissues of the wound or may be absorbed by the body and give rise to general symptoms. Certain of these metabolic products may also destroy the growth-inhibiting action of penicillin. Abraham
MELENEY FL, JOHNSON BA, PULASKI EJ, COLONNA F. TREATMENT OF MIXED INFECTIONS WITH PENICILLINI. With Special Reference to the Adjuvant Action of Parachlorophenol. JAMA. 1946;130(3):121-124. doi:10.1001/jama.1946.02870030001001