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File:IPLab9Clostridium7.jpg|This is a high-power photomicrograph of a tissue section stained with a tissue Gram's stain (Brown & Brenn). The Gram-positive bacilli can be seen throughout this tissue section.
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== Study Questions ==
* <spoiler text="What organism causes myonecrosis (gas gangrene)?">Clostridium perfringens invades traumatic or surgical wounds and causes an anaerobic cellulitis or myonecrosis (gas gangrene). Clostridium species are gram-positive bacilli that grow under anaerobic conditions and produce spores which are frequently present in the soil.</spoiler>
* <spoiler text="What are some of the factors that help Clostridium perfringens produce such a fulminant anaerobic cellulitis?">Clostridia release collagenase and hyaluronidase that degrade the extracellular matrix proteins (collagen and elastin) which make up the connective tissue between muscle bundles. This allows the bacteria to migrate and invade along fascial planes.
C. perfringens secrete 12 toxins, the most important of which is alpha toxin. Alpha toxin is a phospholipase C that degrades lecithin, a major component of cell membranes, and thus destroys red blood cells, platelets, and muscle cells, causing myonecrosis.
Alpha toxin also has a sphingomyelinase activity that contributes to nerve-sheath damage.
Theta toxin binds cholesterol and forms a membrane-destabilizing pore that causes leukocyte lysis, explaining the paucity of polymorphonuclear leukocytes in the lesions of gas gangrene.</spoiler>
{{IPLab 9}}
[[Category: IPLab:Lab 9]]
