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By Mayo Clinic staffYour mouth is naturally teeming with microorganisms, including fungi, viruses and bacteria. Although this might sound unpleasant, most of these microorganisms are actually beneficial because they help break down food and protect you from disease-causing organisms.
In trench mouth, though, harmful bacteria are able to grow out of control. This overgrowth causes infection of your gums. This infection can damage or destroy the delicate gum tissue (gingiva) that surrounds and supports your teeth. Large ulcers, often filled with bacteria, food debris and decaying tissue, may form on your gums, leading to severe pain, bad breath and a foul taste in your mouth.
Precisely how these bacteria destroy gum tissue isn't known. But it's thought that enzymes and toxins produced by the bacteria play a role.