[Detection of endotoxins and enterotoxins of Bacteroides fragilis in culture media].

Four B. fragilis strains were studied one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF). Endotoxin and enterotoxin which are released into the culture medium during the growth of strains were detected. Cultures in BHI broth were incubated for 48 hours at 37 degrees C. After 4, 8, 16, 24 and 48 hours of cultivation, samples of bacterial culture were collected and the optical density was measured. Then the samples were centrifuged, supernatants were filtered through 0.45 micron filters and concentrated three times with 5000 D ultrafilters. Prepared samples were kept frozen at 70 degrees C until use. The presence of endotoxin in samples was revealed by means of immunoelectroprecipitation (IEP) and immunoenzymatic test (dot-ELISA). The assays were performed with antibacterial rabbit immune sera. The activity of enterotoxin was detected on a human colon adenocarcinoma cell line HT 29/C1. The results of the study indicate that endotoxin is released spontaneously by nonenterotoxigenic IPL E 323 strain into the culture medium at the early stages of cultivation. The presence of endotoxin is not demonstrated by means of immunoelectroprecipitation in culture filtrated of ETBF strains. Trace amounts of endotoxin are revealed with dot-ELISA. The activity of enterotoxin is detected after 16 hours of incubation of ETBF strains.