Clostridium perfringens as the flora in the intestine of healthy persons

Perfringolysin O-Induced Plasma Membrane Pores Trigger Actomyosin Remodeling and Endoplasmic Reticulum Redistribution

Clostridium perfringens produces an arsenal of toxins that act together to cause severe infections in humans and livestock animals. Perfringolysin O (PFO) is a cholesterol-dependent pore-forming toxin encoded in the chromosome of virtually all C. perfringens strains and acts in synergy with other toxins to determine the outcome of the infection. However, its individual contribution to the disease is poorly understood. Here, we intoxicated human epithelial and endothelial cells with purified PFO to evaluate the host cytoskeletal responses to PFO-induced damage. We found that, at sub-lytic concentrations, PFO induces a profound reorganization of the actomyosin cytoskeleton culminating into the assembly of well-defined cortical actomyosin structures at sites of plasma membrane (PM) remodeling. The assembly of such structures occurs concomitantly with the loss of the PM integrity and requires pore-formation, calcium influx, and myosin II activity. The recovery from the PM damage occurs simultaneously with the disassembly of cortical structures. PFO also targets the endoplasmic reticulum (ER) by inducing its disruption and vacuolation. ER-enriched vacuoles were detected at the cell cortex within the PFO-induced actomyosin structures. These cellular events suggest the targeting of the endothelium integrity at early stages of C. perfringens infection, in which secreted PFO is at sub-lytic concentrations.

Three-dimensional structure of a putative non-cellulosomal cohesin module from a Clostridium perfringens family 84 glycoside hydrolase

The genomes of myonecrotic strains of Clostridium perfringens encode a large number of secreted glycoside hydrolases. The activities of these enzymes are consistent with degradation of the mucosal layer of the human gastrointestinal tract, glycosaminoglycans and other cellular glycans found throughout the body. In many cases this is thought to aid in the propagation of the major toxins produced by C. perfringens. One such example is the family 84 glycoside hydrolases, which contains five C. perfringens members (CpGH84A-E), each displaying a unique modular architecture. The smallest and most extensively studied member, CpGH84C, comprises an N-terminal catalytic domain with beta-N-acetylglucosaminidase activity, a family 32 carbohydrate-binding module, a family 82 X-module (X82) of unknown function, and a fibronectin type-III-like module. Here we present the structure of the X82 module from CpGH84C, determined by both NMR spectroscopy and X-ray crystallography. CpGH84C X82 adopts a jell-roll fold comprising two beta-sheets formed by nine beta-strands. CpGH84C X82 displays distant amino acid sequence identity yet close structural similarity to the cohesin modules of cellulolytic anaerobic bacteria. Cohesin modules are responsible for the assembly of numerous hydrolytic enzymes in a cellulose-degrading multi-enzyme complex, termed the cellulosome, through a high-affinity interaction with the calcium-binding dockerin module. A planar surface is located on the face of the CpGH84 X82 structure that corresponds to the dockerin-binding region of cellulolytic cohesin modules and has the approximate dimensions to accommodate a dockerin module. The presence of cohesin-like X82 modules in glycoside hydrolases of C. perfringens is an indication that the formation of novel X82-dockerin mediated multi-enzyme complexes, with potential roles in pathogenesis, is possible.

Anticarcinogenic, hypocholesterolemic, and antagonistic activities of Lactobacillus acidophilus

Lactobacillus acidophilus is considered to possess health-promoting attributes. These include anticarcinogenic and hypocholesterolemic properties and antagonistic action against intestinal and food-born pathogens. L. acidophilus can also survive the hostile environment and establish in the complex ecosystem of the gastrointestinal tract. Therefore, the beneficial effects of ingesting L. acidophilus accrue over a longer period than those organisms that cannot colonize the gut. However, the exact mechanisms of these attributes are not known. Presumably, the anticarcinogenic activity may be attributed to production of compounds and/or conditions that inhibit the proliferation of tumor cells, suppression of microorganisms that convert procarcinogens to carcinogens, and degradation of carcinogens formed. They hypocholesterolemic effect is probably exerted by inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, which is a rate-limiting enzyme in endogenous cholesterol biosynthesis in the body and by promoting the excretion of dietary cholesterol in feces as a result of coprecipitation in the presence of deconjugated bile acids in the intestine and/or adsorption by the organisms. The antagonistic effect against pathogens and other organisms is possibly mediated by competition for nutrients and adhesion sites, formation of metabolites such as organic acids, hydrogen peroxide, and production of antibiotic-like compounds and bacteriocins.

Clostridium perfringens and other anaerobes isolated from bile

Clostridium perfringens was isolated from bile in 13 cases of 150 patients examined. The serotypes of C perfringens strains isolated from bile and faeces were investigated using antisera to Hobbs' type 1-17. Two or more serological types were often found in a single specimen, but in the same patient the serotypes of C perfringens strains isolated from the bile were identical with those from the faeces. Beta-glucuronidase production in these C perfringens serotypes was tested with the API-Strep system. Strains agglutinated with Hobbs' antisera produced beta-glucuronidase, but non-agglutinated strains did not.

Extraction of Clostridium perfringens spores from bottom sediment samples

Two extraction-separation procedures were developed and evaluated for use in conjunction with the mCP membrane filter method for the enumeration of Clostridium perfringens spores in bottom sediments. In the more facile of the two procedures, a distilled-water suspension of the sediment sample is pulse sonicated for 10 s and allowed to settle. Portions of the supernatant are then removed for membrane filtration. This procedure is recommended for general use. The more complicated procedure is recommended for situations in which the presence of high levels of toxic materials is suspected or in which relatively low spore densities are present in fine silts. In this procedure, sonication is followed by a distilled water wash. The centrifuged sediment is resuspended in distilled water and mixed with the components of a two-phase separation system (50% polyethylene glycol in distilled water and 25% sucrose in 3 M phosphate buffer [pH 7.1]). After equilibration of the system and low-speed centrifugation, the top phase and interphase are removed, mixed, and membrane filtered. The recoveries of C. perfringens spores by the two procedures, when used in conjunction with the mCP method, were comparable to each other and significantly greater than those by the British most-probable-number method. It was estimated that more than 85% of the spores were recovered by the procedures. The precision of the sonicate-and-settle-mCP procedure was markedly better than that obtained theoretically by the most-probable-number method and approached that theoretically attributable to counting an average of 85 colonies on each of two plates.

New presumptive identification test for Clostridium perfringens: reverse CAMP test

The reverse CAMP test proved to be a highly sensitive test since 97.0% of all Clostridium perfringens cultures tested gave an easily discernible positive reaction.

Persistent high numbers of Clostridium perfringens in the intestines of Japanese aged adults

TSN agar was applicable for enumeration of Clostridium perfringens in fecal samples of adults but not in those of infants. It was demonstrated using TSN agar that some healthy aged adults had persistently carried C. perfringens at levels ranging from 10(7) to 10(9), while some others ranged from 10(3) to 10(6) per ml volume of fecal sample although all of these adults had the same diets. In the test for agglutinability of isolates of C. perfringens collected from two elderly adults, a younger adult and a baby, it was demonstated that most of the isolates obtained from an aged adult of high levels for 19 months belonged the same serotype, while rapid alteration of serotypes could be observed in three other persons with high or low levels. In spite of as many as 10(9) C. perfringens per ml of feces, no trace of a-toxin could be detected in the fecal samples. In in vitro tests, fecal suspension suppressed the production of a-toxin although it allowed the organism to grow sufficiently.

Human fecal flora: the normal flora of 20 Japanese-Hawaiians

Quantitative and qualitative examination of the fecal flora of 20 clinically healthy Japanese-Hawaiian males was carried out by using anaerobic tube culture techniques. Cultural counts were 93% of the microscopic clump counts. Isolated colonies were selected in a randomized manner to give an unbiased sampling of the viable bacterial types. Each isolate was characterized for species identification. From a total of 1,147 isolates, 113 distinct types of organisms were observed. Statistical estimates indicate that these types account for 94% of the viable cells in the feces. The quantitative composition of the flora of this group of people, together with differential characteristics of previously unreported species, is presented for those kinds of bacteria which each represented at least 0.05% of the flora.

Enumeration of fecal Clostridium perfringens spores in egg yolk-free tryptose-sulfite-cycloserine agar

The Shahidi-Ferguson perfringens, tryptose-sulfite-cycloserine (TSC), and egg yolk-free TSC agars have been tested for their suitability to enumerate fecal spores of Clostridium perfringens. When these spores comprised at least 20% of the total anaerobe spores, equally accurate counts were obtained in the three media. With lower ratios of C. perfringens spores, the most accurate counts were obtained in egg yolk-free TSC agar. The median C. perfringens spore count of 60 normal fecal specimens was log 3.4/g. A nonmotile, sulfite- and nitrate-reducing Clostridium, not identifiable with any known clostridial species, was isolated from 14 out of 60 fecal specimans. It was not differentiated from C. perfringens in the nitrite motility test, but could be distinguished by its inability to liquefy gelatin.