Enteroinvasive Escherichia coli Infection

　　First, etiology

　　An intestinal infectious disease caused by EIEC. EIEC is a group of diarrheal Escherichia coli isolated from the feces of dysentery patients in 1967. EIEC has similar biochemical characteristics to Shigella, is non-motile, does not ferment or ferments slowly on lactose, has common antigens, and is an invasive pathogen, also known as dysentery-like Escherichia coli, which can invade epithelial cells and grow and reproduce within them, causing inflammatory reactions. It is important to differentiate between the two, and the differential culture media include citrate medium and sodium acetate medium. Common O serotypes include: O28, O29, O32, O112, O124, O136, O143, O144, O152, O164, O167, etc. EIEC does not produce enterotoxins, mainly invades the colon, and forms intestinal wall ulcers. It has a strong pathogenicity, and only 10 to 100 bacteria are needed to cause disease. Contaminated water and food can cause outbreaks, and it can also be transmitted by contact, forming sporadic cases. Both adults and children can be affected.

　　Second, pathogenesis

　　EIEC invades the intestinal mucosal epithelial cells, releasing endotoxins after bacterial death, which destroy cells to form inflammation and ulcers, causing diarrhea. Clinically, it is rare and mainly affects older children and adults. The clinical manifestations are similar to those of dysentery.

　　Extraintestinal complications of enteroinvasive Escherichia coli infection are not common.

　　Bacteremia is mainly seen in children, in patients with malnutrition, sickle cell anemia, and low immune function. There have been more than 100 cases reported abroad, and a few cases have been reported in China. The symptoms of patients with concurrent bacteremia are more severe, with a mortality rate as high as 46%. Bacteremia is most common within 1 to 2 days after onset, and antibiotic treatment is effective.

　　Hemolytic uremic syndrome is mainly seen in Shigella dysenteriae infections. Some cases initially present with a leukemic reaction, followed by hemolytic anemia and DIC. Some cases may develop acute renal failure, with thrombosis in both renal arteries and renal cortex necrosis, fibrous protein deposition in glomeruli and arterial walls. About half of the cases are positive in the horseshoe crab test, and most cases have positive immune complexes in the serum. Endotoxemia may be related to the onset of the disease, but the endotoxemia caused by other bacteria does not have similar manifestations. The prognosis of this disease is severe.

　　Arthritis often occurs within 2 weeks after dysentery, possibly due to变态反应, mainly affecting large joints, which can cause redness and swelling of the knee and ankle joints, as well as effusion. Agglutinating antibodies against Shigella are present in the synovial fluid, and the serum anti-O titer is normal. Hormonal therapy can quickly alleviate the symptoms.

　　Symptoms include fever, abdominal pain, diarrhea, tenesmus, purulent stools, which are difficult to differentiate from dysentery. A positive EIEC serum agglutination test is necessary for diagnosis, and the Escherichia coli isolated from fecal culture should also be positive in the guinea pig corneal test. Treatment is the same as for dysentery, and antibacterial treatment is required for severe cases.

　　How to prevent enteroinvasive Escherichia coli infection:

　　Enteroinvasive Escherichia coli infection is usually a self-limiting disease, and most patients recover within 1 to 2 weeks. The prognosis is related to the following factors:

　　1. Elderly, weak, infants, and patients with low immune function have more complications and serious prognosis;

　　2. The mortality rate of toxic dysentery is high, especially in respiratory failure type;

　　3. Shigella dysenteriae serogroup I causes more severe symptoms, while Shigella flexneri is more likely to lead to chronic conditions, and drug-resistant strains affect the efficacy;

　　4. The appropriate use of antibacterial drugs is crucial for clearing the infection; improper use, insufficient course of treatment, and delayed treatment all affect the efficacy.

　　1. Specimens:For extraintestinal infections, collect midstream urine, blood, pus, cerebrospinal fluid, etc.; for diarrhea patients, collect feces.

　　2. Isolation, culture, and identification:Directly inoculate the fecal specimen onto selective culture media for enterobacteria. Blood must first be enriched in broth, then transferred to blood agar plates. Other specimens can be simultaneously inoculated onto blood agar plates and selective culture media for enterobacteria. After incubation at 37℃ for 18 to 24 hours, observe the colonies and perform smear staining and microscopic examination. A series of biochemical reactions are used for identification. Enteropathogenic Escherichia coli must first undergo a serological typing test. Necessary to detect enterotoxins. In addition to identifying Escherichia coli, the urinary system should also be counted; only when the bacteria count per milliliter of urine is ≥100,000 does it have diagnostic value.

　　What kind of food is good for the body when infected with enteroinvasive Escherichia coli?

　　It is advisable to have light, hygienic, and healthy food as the main diet, and to reasonably match the diet.

　　(The above information is for reference only; for details, please consult a doctor.)

　　First, treatment

　　1. General treatment:Patients with obvious symptoms must rest in bed and follow the disinfection and isolation procedures for intestinal infectious diseases. The diet should consist mainly of liquid foods. After the condition improves, switch to congee, noodles, and other foods. Avoid eating cold, greasy, and刺激性 foods. Those with dehydration should be appropriately rehydrated. For infants with dehydration within the range of 5% to 10% of body weight, the World Health Organization-recommended Oral Rehydration Salt Solution (ORS) can be used, containing 20g of glucose, 3.5g of sodium chloride, 2.5g of sodium bicarbonate, and 1.5g of potassium chloride per liter of water. After being tested in nearly 2000 cases across China, the average effective rate is 96.9%. For those with repeated vomiting or severe dehydration, consider initial intravenous fluid replacement, and as soon as possible, switch to oral rehydration.

　　2. Antimicrobial therapy:In recent years, the resistance of EIEC to various drugs and antibiotics has been increasing year by year. Currently, most of the commonly used antibacterial drugs such as sulfonamides, streptomycin, chloramphenicol, and tetracycline are mostly resistant, and the clinical efficacy has correspondingly decreased. Bacteria can show multiple drug resistance. Therefore, for the selection of EIEC antibiotics, it should be based on the results of local drug sensitivity tests of epidemic strains or the culture of patients' feces, in order to avoid indiscriminate misuse. Pay attention to drug rotation within a certain area. The evaluation of the efficacy of antibacterial drugs should mainly be based on the negative conversion rate of stool culture, and the negative conversion rate at the end of treatment should reach above 90%. Commonly used drugs include the following:

　　(1) Quinolones: They have the advantages of a broad antibacterial spectrum and easy oral absorption. In recent years, the number of resistant strains has gradually increased, and resistance can also be transmitted through plasmids. For Shigella infection, ciprofloxacin 400-600mg/d is commonly used, taken orally in 2 or 3 doses, for a course of 3-5 days. Other new quinolones are also effective against Shigella infection.

　　(2) Sulfamethoxazole/trimethoprim (sulfamethoxazole-trimethoprim): The dose is 2 tablets/time, 2 times/d, 7 days as a course of treatment. According to our results, the cure rate can reach above 95%. In recent years, resistance has gradually increased, and the efficacy has shown a decreasing trend. It should be avoided in patients with sulfonamide allergy, leukopenia, and incomplete liver or kidney function.

　　(3) Antibiotics: EIEC is mostly resistant to commonly used antibiotics such as chloramphenicol, streptomycin, and ampicillin, and some strains are still relatively sensitive to doxycycline. Most pathogenic bacteria are still relatively sensitive to kanamycin and gentamicin in vitro tests, but they can only be used by injection, and the immediate effect is better. Due to the low concentration of drugs in the intestinal wall tissue, they are not excreted into the intestinal lumen, making it difficult to clear bacteria, easy to relapse, and it is recommended to be used in combination with oral trimethoprim. Studies outside China have shown that cephalosporin antibiotics also have good efficacy against Shigella, and they can also be chosen if necessary.

　　3. Traditional Chinese Medicine Treatment:Berberine 0.3g/time, 4 times/d, 7 days as a course of treatment. Alternatively, raw garlic can be taken orally, or Mahuang decoction can be taken orally, or Bai Tou Weng decoction can be taken orally, all of which have certain effects.

　　II. Prognosis

　　The mortality rate of diarrhea caused by EIEC is relatively high.