Diarrhea is defined as an increase in the number of bowel movements, thin stools, or stools containing mucus, pus and blood, or undigested food. Diarrhea is considered to be caused by the passage of watery stools more than 3 times a day, or total stools of more than 200g per day, with a water content of more than 80%. Generally, those with a disease duration of less than 2 weeks are called “acute diarrhea”; those with a disease duration of more than 2 months are called “chronic diarrhea”. The former is common in clinical practice. Acute diarrhea etiology 1, intestinal diseases (1) infectious diseases: ① bacteria: common Salmonella spp, Shigella spp, Campylobacter spp, Escherichia coli infection. Vibrio cholerae infection caused by cholera has been rare in recent years. In addition, some conditional pathogens such as “Clostridium difficile” cause acute diarrhea after treatment with broad-spectrum antibiotics, endoscopy can be seen in the rectal mucosa covered with “membranous” lesions, and called “pseudomembranous enteritis “② Viruses: such as rotavirus diarrhea; ③ Fungi: uncommon, mostly seen in special populations such as the elderly and infirm, the application of broad-spectrum antibiotics, or the application of immunosuppressive drugs; ④ Other: parasitic infections, such as amoebic enteritis, are less common clinically. (2) inflammatory diseases: ulcerative colitis is often the first manifestation of acute diarrhea with mucopurulent stools, and it is difficult to distinguish it from bacillary dysentery in the early stage; anti-infective treatment is ineffective, plus typical colonoscopic manifestations can confirm the diagnosis; (3) neoplastic diseases. 2, acute poisoning and drug factors: Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Clostridium botulinum and other bacterial enterotoxins contaminated food and cause acute diarrhea. Consumption of toxic mushrooms, puffer fish, or chemicals such as arsenic, phosphorus, lead, mercury, etc. can also cause acute diarrhea. Some constipated patients who take excessive laxatives (such as phenolphthalein/goop, hemp, laxative, etc.) can develop acute diarrhea, which can often be relieved on its own after stopping the medication. In addition, some Chinese medicine or health products containing aloe vera or rhubarb ingredients can also cause diarrhea, should not be taken for a long time. 3, systemic diseases: such as hyperthyroidism often have diarrhea performance. Allergic purpura involving the gastrointestinal tract can cause acute abdominal pain with diarrhea, and even blood in the stool, when the examination of endoscopy can find multiple erosions and ulcers in the gastrointestinal mucosa. In clinical practice, acute gastroenteritis caused by bacterial infection or food contamination with bacterial toxins is the most common. Especially in summer, when food is prone to spoilage, the number of patients with acute diarrhea occurring after an unclean diet increases exponentially, and many hospitals need to open special intestinal clinics to avoid cross-infection of these patients with general patients. What do we need to pay attention to in the clinical management of patients with infectious diarrhea? First, do all patients with infectious diarrhea need to be treated with antibiotics? No. The body has the ability to heal itself. The human body has the ability to heal itself, and the process of diarrhea or vomiting is actually a detoxification process, and the body will recover naturally after the toxins are removed from the body through diarrhea or vomiting. Therefore, many patients with acute diarrhea can be relieved by themselves in 1 or 2 days without medication. However, antibiotics should be given promptly in the following 6 cases: 1. diarrhea more often than 5 times/day; 2. large amount of dilute watery stool, or stool with mucus and pus blood; 3. stool examination reveals more than 3-5 white blood cells/high magnification field; 4. combined fever, especially temperature over 38℃; 5. diarrhea symptoms continue for more than 3 days; 6. laboratory blood test with elevated WBC and neutrophil percentage more than 75%. Second, how to choose antibiotic treatment for patients with infectious diarrhea? Generally, an antibiotic can be used, but when anaerobic infection or antibiotic-associated enteritis is suspected, metronidazole or tinidazole can be used in combination. The preferred route of administration is oral; intravenous fluids may be chosen if there is significant vomiting or if clinical symptoms are severe. If the bacterial culture clarifies the pathogenesis, then antibiotics should be selected according to the drug sensitivity results. Third, pay attention to the rehydration treatment of patients with acute diarrhea A considerable number of patients with acute diarrhea are afraid to eat and drink water because they are worried that eating and drinking will aggravate diarrhea, or they cannot eat because of vomiting, and they do not have timely intravenous rehydration, which results in serious complications such as hypotensive shock, electrolyte and acid-base metabolism disorders, ischemic enteropathy and acute renal failure. Therefore, attention should be paid to the rehydration treatment of patients with acute diarrhea. The easiest way to rehydrate is to give oral rehydration salts, which can also be prepared by yourself with plain water with appropriate amount of sugar and salt. For vomiting patients who can not eat or the presence of hypotension, should promptly open the vein for infusion therapy. Fourth, acute diarrhea patients need to pay attention to what diet? As long as there is no persistent vomiting, severe abdominal pain and blood in the stool, patients should be told not to fast, drink more water, and consume light liquid or semi-liquid food such as juice, rice soup, thin porridge, noodle flakes, etc. in small amounts several times, avoiding greasy, high protein (including milk and eggs), coarse fiber and spicy and stimulating foods. Normal diet can be gradually resumed only after diarrhea symptoms are relieved for at least 1 day.