Gangrene - Gangrene

This is when secondary changes occur in necrotic tissue due to infection with putrefactive bacteria or drying. When necrotic tissue becomes infected with putrefactive bacteria, it turns green-black, becomes dirty, and emits a foul odor. This is called wet gangrene. Putrefactive bacteria can also infect the foci of inflammation, in which case hydrogen sulfide ( _H2S ) is released due to the decay of protein, causing the foci to collapse, become dirty, and become very smelly, which is called gangrenous inflammation. Pulmonary gangrene is a typical example of this condition. Pulmonary gangrene occurs following pneumonia, lung cancer, bronchiectasis, etc., and is often caused by mixed infection with fusiform bacteria and spirochetes, and the foul-smelling sputum will separate into several layers if left untreated. Recently, pulmonary gangrene has been lumped together with lung abscess and called lung suppuration. Gas gangrene is a special type of gangrene. It is an anaerobic bacterial myositis caused by infection of deep puncture wounds, lacerations, compound fractures, and other traumatic injuries with Clostridium perfringens, and is characterized by muscle necrosis, localized crepitation, and an acidic odor. In contrast to wet gangrene, there is also dry gangrene, in which necrotic tissue dries out, and is also known as mummification.

[Yutaka Watanabe]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

壊死(えし)に陥った組織に、腐敗菌の感染や乾燥などによる二次的変化がおきた場合をいう。壊死組織が腐敗菌の感染を受けると緑黒色を呈し、汚くなり、悪臭を放つようになる。これを湿性壊疽とよぶ。炎症の病巣にも腐敗菌の感染がおこることがあり、この場合はタンパク質の腐敗により硫化水素H₂Sが遊離されるので病巣は崩れ、汚く、非常に臭い状態となり、壊疽性炎といわれる。この病状の代表としては肺壊疽があげられる。肺壊疽は肺炎、肺癌(がん)、気管支拡張症などに引き続いておこり、紡錘状菌、スピロヘータなどの混合感染によることが多く、悪臭の強い喀痰(かくたん)は放置すると数層に分かれる。最近、肺壊疽は、臨床的には肺膿瘍(のうよう)と一括して肺化膿症とよばれている。また、壊疽の特殊なものとしてガス壊疽がある。深い刺創、裂創、複雑骨折などの外傷にウェルチ菌が感染しておこる嫌気性細菌性筋炎のことで、筋肉の壊死、局所の捻髪(ねんぱつ)音、酸性臭などを特徴としている。湿性壊疽に対して乾性壊疽もあるが、これは壊死組織が乾燥した状態のもので、ミイラ化ともよばれている。

［渡辺　裕］

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