Enhancement of antibiotic antibacterial activity by experimental pleural exudates.

The aim of this research was to study the synergistic effect of experimental pleural exudates and antimicrobial drugs on various microorganisms. The antibacterial activity of different pleural exudates alone and in the presence of sub-MIC amounts of antibiotics was studied by a continuous recording turbidimetric method. Synergistic action between the antibiotics and the exudates was demonstrated. This phenomenon can be explained by the presence of heat-labile substances that themselves possess only slight antibacterial activity but are able to increase the effect of sub-MIC antibacterial drugs.