This specimen comes from a soldier who was injured by a gunshot wound to the left knee in France during August 1917. Much of the trench warfare in France and Flanders during the first world war took place in what had been cultivated fields that would be fertilised with horse manure, meaning that soil would be rife with the bacteria that cause gas gangrene. Muddy conditions would result in clothing also being covered with soil and bacteria, so if a soldier was wounded, infection was likely. Here we can see a clearly distinct portion in the upper right has become grey and devitalised, and bubbles can be observed in this tissue. The soldier’s leg was amputated to prevent further spread of the disease.
Gas gangrene is a bacterial infection which is potentially life threatening, involving muscle death and blood poisoning. It is usually caused by bacteria of the family Clostridium, especially Clostridium perfringens. These bacteria are anaerobic – that is they live in the soil in an environment low in oxygen. They are normal components of the gut flora of vertebrates, including domestic animals and humans, and hence they are found in soil which has been fertilised with manure. While this bacteria can exist in the human digestive tract in ways that can be beneficial, in other parts of the body they can cause a great deal of harm. If the bacteria are carried into muscle through, for example a bullet-wound, where the bullet picks up bacteria from the clothing as it passes through they encounter anaerobic conditions in the wounded tissue. The anaerobic conditions arise because injury to the circulation can reduce the flow of oxygen-carrying blood through the muscle . This produces the low-oxygen environment that promotes the flourishing of these bacteria and allowing them to produce powerful toxins that will further destroy the adjacent tissue. This process generates a gas – usually a mixture of hydrogen, carbon dioxide, nitrogen and oxygen – which will form bubbles within the tissue. The skin overlying the area will initially turn pale, and then darken to red or purple, and the skin will often crackle if pressed due to the air bubbles within. Other symptoms include fever, an increased heart rate, and a foul-smelling discharge that is more watery than normal pus, due to break down of the white blood cells by the bacterial toxins.
Gas gangrene can spread quickly through tissue if untreated, leading to death. Treatment involves the removal of the infected tissue, often through amputation of a limb, and antibiotics. Hyperbaric chambers, where oxygen is delivered at higher than normal pressure, can also be used to promote a more oxygen-rich atmosphere which inhibits the growth of the bacteria.
While trench warfare at the beginning of the 20th century made gas gangrene relatively common, today it is rare with an incidence that increases dramatically in times of war or natural disaster.