Clinical Significance of Antibody-coated Bacteria (ACB) Detected in Pus and Exudate

Abstract

Our group have evaluated the presence of antibody-coated bacteria (ACB) in pus, exudate and secretions collected from various purulent loci other than those in urinary tract which were reported by Thomas, et al. The results of examination for ACB had a good correlation with a direct method for detecting bacteria by means of Gram stain and pure culture.
In 97 of 168 specimens obtained from 131 cases, bacteriologic culture were positive and ACB were negative. Among these cases, significance of most of the bacteria isolated was not clear. In 39 specimens which were ACB was positive, 35 were positive bacteriologic culture and 4 were negative. In these 4 specimens obtained from the sites apparently having infection, the findings of positive ACB with negative bacteriologic culture suggested that in these cases the presence of ACB was more useful than bacteria culture in establishing a diagnosis. In regard to the frequency of bacteria isolated and bacteria which showed positive fluorescence, E. coli was most frequently seen followed by Bacteroides group, such as α, β, γ-Streptococcus, Enterococcus and S. marcescence were also frequently isolated from the specimens, but ACB were negative in almost of strains. The isolation of Proteus groups was rare, however in most of these cases positive fluorescence were usually observed.
The intensity of fluorescence had a little correlation with the number of bacteria detected. The more bacteria existed, the heavier staining tend to be.
Our results indicate that the immunofluorescence test for ACB in the site of infection provides a simple and reliable diagnostic aid. By using this test, even a small amount of specimens can be examined within a short period; and the morphology, the number of bacteria can also be studied in the test. For this reason, the causative organism can be quickly identified without wasting a lot of time waiting the culture results, therefore the test is useful especially when anaerobic groups appear to be the pathogenic organisms.