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Stools from autistic and healthy children were studied for fecal lactoferrin, Clostridium difficile toxins, Clostridium perfringens enterotoxin and cultured for Clostridium spp. Elevated level of FLA was demonstrated in 24.4% stools, all from boys (31.25%). No toxins were detected. Clostridium spp. was isolated with similar frequency from all samples. C. perfringens were isolated significantly often from the autistic stools, intermediate sensitive strains to penicillin 19%, to clindamycin 11.3%, and to metronidazole 7.5% were detected. Further studies on fecal microflora and inflammatory mediators, with larger groups of patients, are required in order to explain their role in neurological deficits., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

In this study, for the first time, Clostridium histolyticum lethal factor was purified by ammonium sulfate precipitation of culture broth, centrifugation through an Amicon filter device and hydrophobic interaction chromatography. The purified lethal factor was devoid of proteolytic activity. At a concentration of 150 ng mL(-1) the lethal factor killed 50% of HeLa cells within 24 h of exposure. Abrogation of actin filaments, activation of caspases, fragmentation of nuclear DNA as well as ultrastructural changes indicated that the cell death occurred by apoptosis. The apoptotic action of the lethal factor is in agreement with changes induced in animal tissues by administration of C. histolyticum culture medium.

Clostridium histolyticum culture supernatant contains numerous enzymes, which exert a cytotoxic effect on host cells. This includes lethal toxin, clostripain and high-potassium-sensitive toxin. Since the number of C. histolyticum infections increased during the last several years, it seems worthwhile to evaluate whether protease inhibitors, used for the treatment of many diseases, could influence toxicity, and thus, pathogenicity of C. histolyticum. In this study we evaluated in vitro the influence of four common protease inhibitors: aprotinin, phenylmethylsulphonyl fluoride (PMSF), l-1-chloro-3-[4-tosylamido]-7-amino-2-heptanone-HCl (TLCK) and chymostatin on the toxicity of C. histolyticum supernatant towards human epithelial HeLa cells. We show that aprotinin has no effect, while PMSF, TLCK and chymostatin potentiate the cytotoxic activity of C. histolyticum, probably by hindering natural defence mechanisms of cells. In addition, PMSF and TLCK block clostripain enzymatic activity, while chymostatin leaves it intact. Elevated cytotoxicity of the supernatant is not related to the quantity of high-potassium-sensitive toxin, as was reported previously, since desalted supernatant still exerted its strong toxic effect. Our results show that addition of protease inhibitors for treating diseases complicated by concurrent C. histolyticum infection must require special attention.