Vibrio cholerae, is the causative agent of cholera, that infects millions, annually. Chironomids are aquatic insects host V. cholerae. Toxigenic strains produce cholera toxin (CT) which main virulence factor causes symptoms. In contrast to other bacterial pathogens, cholerae produces CT when at low cell densities while hemagglutinin/protease (HAP) a high density-controlled gene. When behavior w...

Background and Aims: Clostridium difficile is an identified cause of antibiotic-associated diarrhea, antibiotic-associated colitis, pseudomembranous colitis and nosocomial diarrhea. The objective of this survey was to determine molecular analysis of toxigenic Clostridium difficile isolates from hospital environment in Tehran tertiary medical centers. Materials and Methods: In this descriptiv...

Two strains of Aspergillus flavus, non-toxigenic NRRL 6550 and toxigenic NRRL 5940, were studied over a period of 44 days, in order to detect the presence of virus-like particles (VLPs) by means of electron microscopy (EM) and nucleic acids electrophoresis. Only the toxigenic strain contained VLPs, presenting three-segmented dsRNA. An increase in VLPs number was observed during the exponential ...

during one year period from 2010 to 2011 the samples from pneumonic animals were taken and transported to the laboratory. pasteurella multocida were identified in 16.6% of animal by biochemical test. the high incidence of p. multocida was obtained in the south of fars province, where the area was warm region. the mean death time between the isolates was 12-18 and 19-24 hours. only the capsular ...

Mycotoxins are natural contaminants in raw materials, food and feeds [1]. Aflatoxins are toxic metabolites produced by different species of toxigenic fungi, called mycotoxins. The discovery of aflatoxins dates back to the year 1961 following the severe outbreak of turkey “X” disease, in the England, which resulted in the deaths of more than 100.000 turkeys and other farm animals. The cause of t...

This review summarises the genetic methods used for chemotype determination of the main Fusarium type B-trichothecene producing species. Literature on Fusarium chemotype epidemiology over the last 15 years is reviewed in order to describe temporal and spatial chemotype distribution of these fungi worldwide. Genetic approaches used for chemotype determination are also reviewed and discussed, hig...

Guinea pigs infected by intradermal injection of living toxigenic diphtheria bacilli and protected by horse antitoxic globulin, given either before or after infection, develop delayed hypersensitivity of the tuberculin type to diphtherial proteins. The highest degree of hypersensitivity is specifically directed against diphtheria toxin (or toxoid) itself, although smaller delayed skin reactions...

Clostridium difficile is a major nosocomial pathogen and the main causative agent of antibiotic-associated diarrhoea. The organism produces two potent toxins, A and B, which are its major virulence factors. These are chromosomally encoded on a region termed the pathogenicity locus (PaLoc), which also contains regulatory genes, and is absent in non-toxigenic strains. Here we show that the PaLoc ...

Toxigenic serogroups O1 and O139 of Vibrio cholerae may cause cholera epidemics or pandemics. Nontoxigenic strains within these serogroups also exist in the environment, and also some may cause sporadic cases of disease. Herein, we investigate the genomic diversity among toxigenic and nontoxigenic O1 and O139 strains by comparative genomic microarray hybridization with the genome of El Tor stra...

The presence of glutathione (GSH) S-transferase activity, using 1-chloro-2, 4-dinitrobenzene (CDNB) as a substrate, has been established in the cytosolic fraction of the toxigenic (aflatoxin producing) and nontoxigenic strains of Aspergillus flavus. Significant differences in the GSH S-transferase activity were observed between the toxigenic and non-toxigenic strains. A positive correlation has...