Proteus is a common species of normal intestinal flora. The main ones related to human infection are common Proteus and mirabilis. They can cause urinary tract infection and abdominal postoperative incision infection. Pneumonia is rare, and there is no exact incidence statistics in China. It is rare in community infection and accounts for about 3.4% to 5.8% of hospital infection. Similar to other Gram-negative bacillus pneumonia, it is mainly inhaled Proteus colonized in the oropharynx. Normal people rarely carry this bacteria. The colonization of Proteus in the oropharynx increases in the elderly, those who use antacids or H2 receptor blockers to increase gastric pH, those with poor personal hygiene, and those who undergo gastrointestinal surgery. When the body's resistance decreases and the amount of inhaled bacteria is large and the toxicity is strong, pneumonia will occur.