neonatal hemorrhagic Escherichia coli enteritis
Introduction
Introduction to neonatal hemorrhagic E. coli enteritis Neonatal hemorrhagic Escherichia coli enteritis is an intestinal infectious disease caused by enterohaemorrhagic Escherichia coli (EHEC). EHEC is the causative agent of hemorrhagic enteritis, mainly Escherichia coli O157:H7, which is a newly discovered diarrhea-causing Escherichia coli in 1982. In addition, O26:H11 may also be one of the pathogens. There is no official report yet in China. Poultry and livestock are the storage host and the main source of infection for the disease. The population is generally susceptible, but mainly for the elderly and children. There is a clear seasonality, with peaks of 7, 8 and 9 months. Typical manifestations are acute onset, diarrhea, initial watery stools, followed by bloody stools. With abdominal pain, no fever or low fever, may be associated with nausea, vomiting and sensation-like symptoms. Those without comorbidities will recover naturally within 7 to 10 days. A small number of patients have a course of 1 to 2 weeks. basic knowledge The proportion of illness: 0.012% Susceptible people: good for newborns Mode of infection: digestive tract spread Complications: uremia thrombotic thrombocytopenic purpura
Cause
Causes of neonatal hemorrhagic Escherichia coli enteritis
Cause
Escherichia coli O157:H7 is different from other serotypes of Escherichia coli and grows well at 30-42 °C, but the optimal growth temperature is still 37 °C. The slow-fermented sorbitol-McKay (SMAC) medium can be used as Screening medium for O157:H7. On the SMAC medium, the O157:H7 colonies were colorless, while the fermented strains were pink, but half of the EPEC strains had characteristics similar to O157:H7, and attention should be paid to the identification of EPEC and EHEC. Escherichia coli O157:H7 is resistant to acid and low temperature, pH 2.5-3.5, temperature 37 °C, can withstand 5h without losing activity, and can survive in the refrigerator for a long time. Not heat resistant, killed at 75 ° C for 1 min. Escherichia coli O157:H7 does not contain the general enterotoxin gene code, does not produce LT, ST by gene probe and animal test, is not invasive, does not belong to EPEC serotype, can produce a large number of Shiga-like toxins (Shiga -Like toxin, referred to as SLT). SLT is antigenic and can be neutralized by rabbit antiserum of Shiga type I toxin. Because SLT can denature, dissolve and die of Vero cells (ie, African green monkey kidney cells), it is also called Veto toxin, or VT for short. Among the toxins produced by bacteria, VT is one of the strongest toxins. Heating at 98 ° C, 15 minutes can be inactivated. According to different antigenicity, it is divided into two types: VT1 and VT2. The structure is composed of 1 A subunit and 5-6 B subunits. The molecular weights were 3,300 and 8,000, respectively.
Pathogenesis
EHEC invades the human body from the oral cavity. After reaching the intestinal lumen, it adheres to the brush border of the intestinal villi with the help of pili. The B subunit binds to the intestinal epithelial cell glycolipid receptor GB3, and the A subunit has toxin activity and enters the cell. It also inhibits protein synthesis and damages intestinal epithelial cells. The focus is on the cecum and colon. The diffuse hemorrhage and ulcer of the intestinal mucosa are visible to the naked eye. In addition to intestinal epithelial cells, GB3 receptors are also widely present in vascular endothelial cells, kidney and neural tissue cells, damaging vascular endothelial cells, red blood cells and platelets leading to HUS. Extensive tubular necrosis can lead to acute renal failure. The excitability of parasympathetic nerves is enhanced by the action of toxins, sinus bradycardia and convulsions can occur, and Vero toxin also stimulates the release of factor VIII by endothelial cells, resulting in thrombotic thrombocytopenic purulent thrombocytopenic purpura.
Prevention
Neonatal hemorrhagic Escherichia coli enteritis prevention
Prevention of hemorrhagic Escherichia coli enteritis, in addition to common with other intestinal infectious diseases, such as washing hands before and after meals, to protect food water source hygiene, the focus should be on the management of frozen fast food, to prevent food contamination, before eating Fully heated.
Complication
Neonatal hemorrhagic Escherichia coli enteritis complications Complications uremia thrombotic thrombocytopenic purpura
Concomitant hemolytic uremic or thrombotic thrombocytopenic purpura.
Symptom
Neonatal hemorrhagic Escherichia coli enteritis symptoms Common symptoms Diarrhea watery stool abdominal pain nausea and vomiting weakness Hematuria jaundice coma
The incubation period is 1 to 14 days, usually 4 to 8 days. Before the illness, there may be a history of processing frozen food semi-finished products for fast food. There are three clinical types of asymptomatic infection, mild diarrhea, and hemorrhagic enteritis. Typical manifestations are acute onset, diarrhea, initial watery stools, followed by bloody stools. With abdominal pain, no fever or low fever, may be associated with nausea, vomiting and sensation-like symptoms. Those without comorbidities will recover naturally within 7 to 10 days. A small number of patients in the course of 1 to 2 weeks, secondary to acute hemolytic-uremic syndrome (HUS), manifested as pale weakness, hematuria, oliguria, anuria, subcutaneous mucosal bleeding, jaundice, coma, convulsions. More common in the elderly, children, immune function, the mortality rate of 10% to 50%.
Examine
Examination of neonatal hemorrhagic Escherichia coli enteritis
1. Bacterial culture separation
Increasing the positive rate of stool culture can increase the rate of diagnosis and affect the factors of culture, mainly the characteristics of stool, disease course and medium. Bloody stools, short course of disease, high positive rate, watery stool, long course of disease, especially more than 7 days, the positive rate is low. Sorbitol-Maconcon agar (SMAC) increases the positive rate.
2, immunological testing
Direct ELISA was performed using a monoclonal antibody to detect O157:H7 Escherichia coli.
3, genetic testing
The sensitivity and specificity of EHEC-specific DNA probes can reach 99%, or the EHEC DNA sequence analysis by PCR can be found to be unique to EHEC. Its specificity is strong and sensitive, 3~4h can be used. The results. Other multiplex PCR methods for simultaneous amplification of two pairs of oligonucleotide primers, SLT1 and SLT2, have not been widely used in clinical practice. Genetic testing can be used for clinical research and epidemiological investigations.
4, X-ray examination showed submucosal edema of the ascending colon and the model colon.
Diagnosis
Diagnosis and diagnosis of hemorrhagic Escherichia coli enteritis
diagnosis
In addition to epidemiological and clinical features, O157:H7 Escherichia coli and its toxins can be diagnosed from the stool.
Differential diagnosis
It should be differentiated from other Escherichia coli enteritis.
