P-fimbriae-producing septicaemic Escherichia coli from poultry possess fel-related gene clusters whereas pap-hybridizing P-fimbriae-negative strains have partial or divergent P fimbrial gene clusters

Article Abstract:

P fimbriae associated with Escherichia coli strains causing colisepticaemia in poultry was examined by PCR and Southern blot hybridization. Of the 13 strains, five were P-fimbriae-expressing (P-positive) and eight were P-fimbriae-non-expressing (P-negative). PCR amplifications using probes specific for I, B, A, C or G genes in the pap operon showed positive amplification of sequences to the C and B genes in the P-positive strains, but no PCR amplification was observed in the I gene. Restriction endonuclease EcoRI digests of genomic DNA from each of the strains showed polymorphisms between the P-positive and P-negative strains. Hybridization of PstI digests with the A gene probe revealed a felA gene which encodes the major structural gene of fimbriae.

Bacteria, Bacterial adhesion, Septicemia

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Production of Escherichia coli STb enterotoxin is subject to catabolite repression

Article Abstract:

The production of thermostable toxin b(STb) increases proportionately with bacterial growth and is dependent on metabolite repression. Enterotoxigenic Escherichia coli secrete many heat-stable and heat-labile enterotoxins that cause diarrhoea in humans and animals. STb belongs to the methanol-insoluble type of toxin and affects pigs. The use of mutants is necessary since wild-type strains do not produce much of the toxin and the amount of toxin present in the culture is measured using a quantitative STb-specific inhibition 'ELISA'.

Observations

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Escherichia coli STB enterotoxin

Article Abstract:

Escherichia coli STb enterotoxin has been linked to diarrhoea illnesses of porcine origin. However, STb gene was alo found to be present in bovine, chicken and even human enterotoxigenic E. coli (ETEC) strains. STb has been documented as having effects on intestinal tissue through two possible mechanisms. It mediates the level of prostaglandin E2 which regulates water and electrolyte in diarhoea. The second mechanism involves the receptor-operative calcium channel in the plasma membrane.

Bacteria, Pathogenic, Pathogenic bacteria

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