LABORATORY AND CLINICAL STUDIES ON POLYMICROBIAL INFECTION IN THE SURGICAL FIELD

There are many cases of polymicrobial infection experienced during daily clinical procedure in the surgical field, and it is important in such cases to clarify the types of bacteria responsible for the infection and constituting the infectious fields. These aspects were investigated by examining diseases known to have a high incidence. In the present study, 1, 093 strains of bacteria, which were isolated from the bile, appendiceal contents, and ascites due to peritonitis, abdominal drainage and wound infection, were used. Polymicrobial infection was found for 42.3% of all strains, especially 65.5% of the strains isolated from cases of peritonitis. As for combinations of bacteria, the incidence of combination of Escherichia coli with Bacteroides fragilis was largest, while 98.1% of Bacteroids fragilis was isolated together with other strains. Experiments for observing changes in infectious virulence due to polymicrobial infection clearly revealed enhancement of virulence, suggesting that chemotherapy should be conducted for bacteria showing a high MIC value with regard to administration of antimicrobial agents for polymicrobial infection.