Dr. Hesham M. Abdulla & Sahar A. El-Shatory
Faculty of Science, Suez Canal University, Ismailia, Egypt
Bacteria are group of minute (0.5 â€“ 2Âµm across), unicellular prokaryotic organisms. They are widespread, almost everywhere in the environment, living either saprophytic on organic matter or parasitic on other organisms. Bacterial toxin, is a specific substance, often a metabolic product of the bacterial cell, which damages other organisms. Bacterial toxins are either exotoxins or endotoxins. Exotoxins are heat labile proteins that are released as the bacteria grow. They are lethal in very small doses (Âµg/kg amounts); e.g. botulinum toxin. They are categorized, according to mechanism of action, into neurotoxins (nerve tissue), enterotoxins (internal mucosa) and cytotoxins (general tissue). Endotoxins are lipopolysaccharides in the cell wall of some bacteria, which is released during bacterial lysis, and is toxic under many conditions. They are heat stable and toxic only at high doses (mg/kg amounts); causing general systematic effects, e.g. diarrhoea and inflammation.