Other Salmonella infections

Introduction to other Salmonella infections It is an acute infectious disease caused by various Salmonella (Salmonellae). Salmonella typhimurium and Salmonella paratyphi A. are commonly referred to as Salmonella typhi, although they are also belonging to Salmonella, but due to traditional habits and pathological changes of typhoid and paratyphoid fever. And clinical manifestations have certain characteristics, so it has been introduced separately, therefore, other Salmonella infections refer to non-typhoidalsalmonellosis caused by non-typhoid Salmonella. The main mode of infection of this disease is caused by eating meat, egg products and dairy products contaminated with Salmonella. Due to the difference in pathogenic bacteria and body reactivity, its clinical manifestations are more complicated, and can be divided into gastroenteritis type, typhoid type, sepsis type and local suppurative infection type. In addition, it can also be expressed as urinary tract infection and asymptomatic infection. . basic knowledge The proportion of illness: the probability of population 8% Susceptible people: no specific population Mode of infection: by eating infection Complications: osteomyelitis meningitis

Other causes of Salmonella infection

(1) Causes of the disease

Salmonella belongs to the genus Enterobacter. Since the isolation of Salmonella choleraesuis by Salmon and Smith in the porcine cholera epidemic in 1885, more than 2,000 serotypes have been discovered so far, according to their biochemical characteristics, can be divided into 1, 2, 3a, 3b, 4, and 5 subgenus, each subgenus is divided into various serotypes according to the structural characteristics of bacterial antigen (O) and flagellar antigen (H), most of which are pathogenic to human body Salmonella belongs to the first subgenus, such as Salmonella typhi, Salmonella paratyphi, Salmonella cholerasuis, Salmonella typhimurium, Salmonella enteritidis ), Salmonella-la bois-morbificans and Salmonella anatis, each of the subgenus Salmonella has its biochemical characteristics, according to the isolation of Salmonella against various salts and sugars The use, decomposition ability, and cleavage by 0-1 phage can identify which subgenus the Salmonella strain belongs to.

Salmonella is a Gram-negative bacillus, the rod is in the shape of a rod, the size is (0.6 ~ 1.5) m × (2.0 ~ 5.0) m, there are more flagella around the bacteria, belonging to the genus Periwinkle, most of the Salmonella It is sporty and quite active. Salmonella has no capsules and no spores.

Most of the Salmonella can grow on common medium and develop well. After 37~18h culture in 37%, the colony diameter can reach 2~3mm, round, smooth, translucent, moist, and the edges are neat. Some Salmonella isolated from sewage or food, the colonies may be marginal, rough, dry and dull, a small number of Salmonella, such as Salmonella choleraesuis, Salmonella serrata and Salmonella abortus in common nutrition Poor growth on the medium, Salmonella biochemical reactions are more complex, the same species of Salmonella can have atypical biochemical reactions, however, most Salmonella can ferment glucose, maltose, sugar, xylose, mannose and Sorbitol, acid production, gas production (S. typhimurium does not produce gas), except for some (such as some Salmonella typhimurium can ferment lactose), do not ferment lactose and sucrose, suitable growth temperature is 37 ° C, suitable The pH is pH 6.8-7.8. Salmonella is more resistant to the outside world. It can survive for several months in water, milk and meat. When the temperature is 22~30%, it will be 2~4h in food. Can quickly multiply, Can also survive winter in frozen soil, not strong against heat, 55% effect on 1h or 60% effect 15 ~ 30min is killed, 5% phenol solution or 0.2% mercuric chloride solution can kill it in 15min Salmonella has similar antigenic structures to other Enterobacteriaceae bacteria, such as bacterial antigen (O), flagellar antigen (H) and surface antigen (Vi). The bacterial antigen is the main basis for the serological typing of Salmonella. Its chemical composition is lipopolysaccharide, and more than 60 kinds of bacterial antigens have been found. Some of the bacterial antigens of Salmonella can be mutated in growth and reproduction. The flagellar antigen of Salmonella is protein, according to the characteristics of its flagellar antigen. It is divided into I phase bacteria and phase II bacteria. Phase I bacteria can agglutinate with the same kind of H factor antiserum; Phase II bacteria can be induced in the medium containing the same kind of H factor antiserum, they lose the same The ability of the H-factor antiserum to agglutinate, it can be seen that the flagellar antigen of the phase I bacteria is more specific, while the flagellar antigen of the phase II is more specific, and the surface antigen is N-acetyl-galacturonic acid homopolymer. , less stable, in some Salmonella, may lack Vi antigen According to these relatively simple biochemical and agglutination tests, the initial identification of Salmonella can be made, but the determination of the serotype depends on the agglutination test using different antiserums. In addition, phage can be applied to certain serotypes (such as rats). Salmonella typhimurium is further identified. In Salmonella, Salmonella associated with human and animal diseases are mainly classified into dozens of serotypes of A to F, and some are pathogenic to humans, such as Salmonella. Salmonella typhi, paratyphoid A and Salmonella, some of which are pathogenic to animals and humans, such as Salmonella paratyphi, Salmonella typhimurium, Salmonella enteritidis and Salmonella choleraesuis; others only The pathogen of animals is not pathogenic to humans. The pathogenicity of Salmonella can be significantly different due to different serotypes or different strains of the same serotype. For example, Salmonella typhimurium usually causes latent infection or gastrointestinal infection. Inflammation, only occasional bacteremia; Salmonella choleraesuis usually cause sepsis or local suppurative infection, only when it causes gastroenteritis or recessive infection; Salmonella typhimurium sometimes causes bacteremia or latent infection, But usually leads to gastroenteritis.

(two) pathogenesis

Salmonella enters the human body by mouth, and it can cause mucosal inflammation in the intestinal tract. The clinical manifestations are gastrointestinal symptoms. Some experimental animal models have shown that Salmonella does not produce enterotoxin, and swallowing a large number of dead bacteria does not cause disease. Salmonella infection is caused by live bacteria. The pathogens multiply in the intestine, causing local inflammation, causing colonic mucosal congestion, edema, inflammation and exudation. In severe cases, bleeding, erosion and ulceration can occur, when Salmonella reaches the submucosal lamina propria. If the function of the lamina propria defense system is relatively imperfect, Salmonella can enter the blood circulation, produce bacteremia and form local infection lesions. The consequences of Salmonella entering the human body depend on the type, quantity and virulence of the bacteria. The intensity and host immune status, various Salmonella may cause asymptomatic infection, acute gastroenteritis, bacteremia or sepsis, localized suppurative infections, similar to different types of clinical manifestations of typhoid, however, some sandmen Bacteria have a tendency to manifest as a clinical type, such as Salmonella typhimurium often causes asymptomatic infections or gastroenteritis, but rarely invade Liquid circulation; on the contrary, Salmonella choleraesuis only occasionally produces gastroenteritis or asymptomatic infection, but often causes sepsis or localized purulent infection, different strains, and even different strains may have pathogenic differences, human volunteers Studies have shown that a large amount of Salmonella (105-106) is required to cause gastroenteritis in healthy adults. The 1% or 10% of the above-mentioned bacteria can only cause temporary bacterial status, and different serotypes can cause infection. There are also large differences in the amount. Unlike normal adults, infants, the elderly, and people with reduced immune function may also cause a small amount of Salmonella to cause disease. The condition of the body also plays an important role in whether or not the disease occurs. In patients with chronic diseases, the chance of serious salmonellosis increases, and patients with cirrhosis are more prone to Salmonella infection. In cirrhosis, the patient's gastrointestinal circulatory dysfunction and dysfunction, systemic resistance is reduced, so Salmonella is prone to occur. Gastroenteritis, in addition, the liver can filter bacteria from the intestines in the blood of the portal vein. If the liver function is damaged, it can cause bacteremia. It has been reported that 25 cases were not found during laparotomy. The sclerotherapy patients were cultured in portal vein blood, 23% of which were positive, while the blood collection in the arm vein was negative, indicating the importance of normal liver filtration. In cirrhosis, there is a traffic branch between the portal vein and the hepatic vein. Portal vein blood from the intestinal tract can enter the systemic circulation without filtering through the liver. Moreover, due to portal hypertension during cirrhosis, blood from the intestine can bypass the liver through the collateral circulation and enter the systemic circulation. Therefore, there are a considerable number of Intestinal bacterial bacteremia can occur in patients with cirrhosis, including Salmonella bacteremia, various diseases such as malignant histiocytosis, lymphoma, dermatomyositis, systemic lupus erythematosus, etc. After treatment with adrenocortical hormone Reduce the body's resistance to various infections, prone to Salmonella infection, stomach surgery, such as major gastrectomy, gastrointestinal anastomosis, etc., easy to occur Salmonella gastroenteritis, the reason may be due to reduced gastric acid secretion after surgery The food enters the small intestine and colon too quickly, the normal flora of the intestine changes, the concentration of hydrogen ions in the intestine changes and the gastrointestinal anastomosis After the reduction of nutrient absorption, the pathological changes of salmonellosis are related to the species, clinical type, etc. Gastrointestinal type of gastrointestinal congestion, edema, bleeding spots, and intestinal lymph node lesions are particularly significant, sepsis type Similar to the pathological changes in sepsis caused by other bacteria, Salmonella in the blood circulation can reach various organs and tissues, producing single or multiple purulent lesions.

Other Salmonella infection prevention

Pay attention to food hygiene and strengthen meat, egg food management is the main measure to prevent this disease, strengthen the food hygiene education for the masses, strengthen the health education for the cooks, canteens and restaurant managers, improve their health knowledge, do not eat Diseased livestock, poultry meat and internal organs, all meat, animal internal organs and eggs must be fully cooked before they can be eaten, do a good job in the cafeteria, food and beverage stores, all cooking utensils, utensils must be cleaned frequently, Disinfection, raw and cooked foods should be separated from the container. When making, separate the knife and the board, and strengthen the food hygiene management. The livestock slaughtering process should be in accordance with the hygienic operation. The intestinal bacteria should be prevented from contaminating the meat, and the meat should be sanitized. Only qualified persons can be sold in the market. When animals die, it is forbidden to slaughter, sell and eat. For the slaughterhouse, meat market, meat and egg products processing, transportation and storage, pay attention to cleaning, disinfection and extinguishment. Rats, flies, cockroaches, etc., in order to prevent food from being contaminated by pathogens, pay attention to water source protection, strengthen drinking water management and disinfection work, raise livestock, poultry Pay attention to avoid Salmonella infection, keep the place to meet the hygiene requirements, the feed is not contaminated by Salmonella, the transportation process should be quick and free from fatigue, so as to reduce the chance of mutual infection, the slaughterhouse should pay attention to cleanliness and avoid Animals should be concentrated in slaughterhouses for a long time to prevent the spread of infection in animals. Patients should be prevented from spreading Salmonella in the population. Patients in the acute phase should be treated in isolation. Those who are carriers or chronic carriers should not be involved in food treatment during the recovery period. Work, and should strictly abide by personal hygiene, antibiotics can be used to treat chronic carriers, to terminate the state of bacteria, for oral immunization for active immunization, is currently being developed, has been carried out animal tests, initially considered safe and effective Whether it can be used for the prevention of Salmonella infection in humans in the future is for further study.

Other complications of Salmonella infection Complications osteomyelitis meningitis

Salmonella typhimurium can cause multiple intestinal infections such as osteomyelitis and meningitis.

Other symptoms of Salmonella infection Common symptoms Intestinal hemorrhage, nausea, intestinal perforation, diarrhea, relaxation, hot abdominal pain, indifferent expression

The length of the incubation period is related to the number of Salmonella infections, the pathogenicity of the strain and the clinical type. After eating food contaminated with Salmonella, gastrointestinal symptoms often occur in 8 to 48 hours. If the amount of infected bacteria is large, It can occur within 12 hours. A small amount of infection takes a long time due to pathogen reproduction. The incubation period can be about 48 hours. The incubation period of sepsis and typhoid type is longer, about 1 to 2 weeks.

Gastroenteritis type

Is the most common clinical type, also known as Salmonella food poisoning, accounting for about 70% of salmonellosis, incubation period of 6 ~ 48h, the shortest 2h, up to 3 days, acute onset, beginning with nausea, vomiting Then, abdominal cramps and diarrhea appear quickly. At first, most of them are loose stools. Then the stools often have yellow water samples. Each time, the amount is more, with little or no fecal matter. Even mucus or pus and bloody feces, stool daily. From time to dozens of times, often have fever, body temperature can reach 38 ~ 40 ° C, may be accompanied by chills or chills, the severity of Salmonella gastroenteritis varies greatly, a few patients may have no fever, only rare Stool, heavy can be violent, accompanied by rapid dehydration, can cause shock and kidney failure due to severe dehydration, and can even die quickly, this situation is more likely to occur in premature and malnourished infants, Salmonella The symptoms of gastroenteritis disappear more than 2 to 3 days after starting treatment. Occasionally, the course of disease can be postponed to 2 weeks, and the mortality rate can exceed 1%. The death cases are almost all infants, elderly and debilitated patients, and the number of white blood cells of patients. More normal Scope, but there is a neutrophil nucleus left shift phenomenon, blood culture in all cases is almost negative, in almost all cases of acute stool can be cultured to isolate pathogens, 2 weeks after the start of gastroenteritis, about 50% There is still pathogen growth in the stool culture. The more common pathogen is Salmonella typhimurium. In China, Salmonella typhimurium infection accounts for about 20% of all Salmonella infections, second only to Salmonella typhimurium infection, in the United States, rats. Salmonella typhimurium infection ranks first in Salmonella infection. In recent years, the number of reported cases of Salmonella typhimurium infection has increased. It is the main pathogen causing acute food poisoning. In the reported Salmonella food poisoning. Salmonella typhimurium is the first, about 30%, followed by Salmonella choleraesuis. The incubation period of Salmonella typhimurium food poisoning is short, mostly 2 ~ 24h, rapid onset, chills, fever, body temperature is generally 38 ~ 39 ° C, with headache, lack of appetite, nausea, vomiting, abdominal pain, diarrhea, stool several times a day to dozens of times, initially with a loose stool, followed by a yellow water sample, with a small amount of sticky The individual can with pus and blood, bad smell, children may experience high fever, convulsions, coma, dehydration, circulatory failure, little or no urine.

If it is not diagnosed and treated in time, it is easy to cause death. In most areas of China, there are reports of the spread of Salmonella typhimurium infection. In the early 1970s, the disease was prevalent in the northwestern region. Since then, North China, East China and South China have successively It is reported that food poisoning caused by Salmonella typhimurium contains a large number of pathogenic bacteria in the stool. If it is not diagnosed, isolated and treated in time, the pathogen can cause serious and widespread pollution, so that the following cases continue to appear, such as in Shenyang. In a children's hospital pediatric ward, due to the treatment of children with typhoid Salmonella typhimuritis, the floor, doors and windows, walls, utensils, such as sheets, mattresses, bed frames, bedside tables, toys, thermos, brooms and rags, etc. It is contaminated by pathogenic bacteria, and Salmonella typhimurium can be isolated even in the air of the ward. If the ward is not completely disinfected, it is difficult to stop the continuation of the hospital due to infection in the hospital. A hospital in Shandong Province has also reported that it has been treated. Children with typhoid Salmonella typhimurium gastroenteritis and severely contaminated the ward, hospitalized in the pediatric ward within 5 months and accompanying person The disease is prevalent, the incidence rate is as high as 54.9%, and the mortality rate is 31.6%. Doctors check, nurses take care, and ward workers can play a role in the spread of this disease. A hospital in Henan Province is in 1 In the first half of the year, 140 cases of Salmonella typhimurium gastroenteritis were treated, of which 78 cases were hospital infections, accounting for 55.7% of all cases. The shortest hospital stay was 3 days, and the longest one was hospitalized after 28 days. 66 cases occurred within 5 days, accounting for 84.6%. The reason for the epidemic was that the ward was contaminated during the treatment of patients, the patients were crowded, the rate of escort was high, and the disinfection and isolation system was not strict. It may be a contributing factor due to Salmonella typhimurium. The host is extensive and there are many routes of transmission, so it is easy to cause epidemics. Most of the patients are infants, and about 90% of patients under one and a half years old.

Typhoid type

The clinical symptoms are similar to mild typhoid fever, but the incubation period is shorter, with an average of 3 to 10 days. The course of disease is also short, usually 1 to 2 weeks, and the condition is lighter. The heat type is relaxation heat or heat retention. The expression is indifferent, relatively slow pulse, even rose rash can be found, diarrhea is more common, intestinal bleeding and intestinal perforation rarely occur, typhoid fever occasionally with gastroenteritis as a precursor, typhoid fever after typical gastrointestinal symptoms The number of white blood cells in the blood is reduced, blood and stool culture may have pathogen growth, and the Salmonella typhimurium which is often caused by typhoid fever is Salmonella choleraesuis.

Septicemia

This type of case is sporadic, common in children and patients with chronic diseases, the onset of more rapid, but also slow onset, fever, chills, sweating and gastrointestinal symptoms, heat type is irregular, relaxation Hyperthermia or intermittent heat type, high fever lasts for 1 to 3 weeks. If there are complications, such as suppurative lesions, the fever can be prolonged for a long time, even for several months, or as a repeated acute attack. Liver and spleen are often swollen, and even jaundice, sputum and meningeal irritation can be seen. In most cases, the number of white blood cells is in the normal range. The blood culture has pathogen growth, but the stool culture is often negative, which is different from the persistent bacteremia of typhoid fever. Intermittently enter the blood circulation, the most common pathogen is Salmonella choleraesuis.

4. Local suppurative infection

The patient has a bacteremia stage in the past or on admission. One or more local suppurative lesions may occur in the febrile phase or after fever. They may also be complicated by mild cases or have no symptoms before the onset. Suppurative lesions may be Occurrence of any part of the body, becoming the main clinical manifestations, bronchial pneumonia, lung abscess, pleurisy, empyema, endocarditis, pericarditis, pyelonephritis, arthritis, costal cartilage abscess, rib osteomyelitis and meningitis are more common In addition, mumps, orchitis, spleen abscess, intraperitoneal abscess, breast abscess and subcutaneous abscess have also been reported, the clinical manifestations of patients vary widely, but most patients have a temporary increase in body temperature and peripheral blood leukocytes Increased number of patients, in some diseases, such as sickle cell anemia, prone to localized purulent lesions, suppurative lesions are more likely to occur in the local lesions, such as hematoma, infarction, cysts, neoplasms and aneurysms Etc., Salmonella meningitis is more common in infants, especially newborns, and the clinical manifestations are similar to other bacterial meningitis, but the course is longer. And more likely to relapse, the mortality rate can reach 40% to 60%, Salmonella pneumonia is more common in the elderly, especially in patients with existing diabetes, tumor, cardiovascular disease and chronic lung disease, can form lung abscess, mortality Higher, up to 50%, the four clinical manifestations of Salmonella infection are often difficult to clearly distinguish, often overlap each other, such as gastroenteritis may be associated with or secondary bacteremia, septic type is more common with local suppurative lesions, In addition, Salmonella infection can also be manifested as acute genitourinary tract infections, poultry, livestock or wild animals can be infected by a variety of Salmonella at the same time, and meat can be in contact with each other during processing, storage, transportation and sales, so Humans can also be infected with two or more Salmonella at the same time.

Inspection of other Salmonella infections

Blood picture

The number of white blood cells in the peripheral blood is mostly in the normal range, and it is also increased or decreased. When local suppurative infection occurs, the number of white blood cells in the blood increases, while those who resemble typhoid fever often decrease.

2. Bacterial culture

Gastroenteritis type can be cultured from vomit, feces, and suspicious foods, and pathogenic bacteria are isolated. Among them, Salmonella typhimurium, Salmonella enteritidis, Salmonella choleraesuis, Salmonella typhimurium and Salmonella typhimurium infection are more common. Studies have shown that the positive rate of rectal swab culture is higher, typhoid type, sepsis type can be cultured from blood, pathogens are isolated, and some cases can be cultured from local suppurative lesions or secretions to isolate pathogenic bacteria for acute gastrointestinal In patients with inflammation, the fecal specimens can be simultaneously inoculated on a strongly selective SS agar medium and a weakly selective MacConkey medium, and after 37 ° C overnight, pick up suspected colonies that do not ferment lactose, and inoculate the trisaccharide iron medium. Upper culture, and serological typing, for patients who have been treated with antibacterial drugs or in the late stage of the disease, because the amount of Salmonella in their feces is already small, the above direct culture method sometimes has false negative results, in order to improve the culture. For the positive rate, 0.5% selenite broth or tetrasulfonate broth can be used as the enrichment agent, and about 1 g of the stool sample is inoculated into 10 ml of the bacteriostatic agent. After overnight at 37 °C, and then transferred to the above medium for culture, the Beijing Epidemic Prevention Station introduced phosphate buffered peptone as the enrichment medium, inoculated with the specimen and placed at 37 °C, and the culture was enhanced for 5-6 hours. The effect of different serotypes of Salmonella on the growth of various selective enrichment media is quite different. There is currently no ideal enrichment medium for all kinds of Salmonella. The effect of enrichment, such as 0.5% selenite broth, has good enrichment effect on Salmonella typhimurium and Salmonella paratyphi A, but inhibits growth of Salmonella choleraesuis, Salmonella abortus, etc. The effect of increasing the culture temperature in the selective enrichment culture, reaching 43 ° C, culture for 18 ~ 24h, in addition to Salmonella typhimurium, generally can significantly enhance the selection effect of the enrichment medium, for Escherichia coli, Proteus, Both Pseudomonas and non-pathogenic bacteria that do not ferment lactose have strong inhibitory effects, making it appear more pure colonies on the culture plate, making it easier to separate and identify further strains, from blood, urine and pus Equivalent specimen The method for isolating Salmonella is basically the same as the method for isolating Salmonella from fecal specimens. Separating Salmonella from blood can extract 5 ml of venous blood from the patient, and immediately inoculate 50-100 ml of 0.5% to 1% glucose bile broth or Glucose broth enrichment solution, cultured at 37 ° C, daily inoculated with platinum ring to inoculate the selective medium or blood agar medium, usually inoculated for 3 days, if necessary, continuous inoculation for 2 weeks, from Urine, sputum, serosal fluid, and pus in the isolation of Salmonella, the specimen can be centrifuged first, 3000r / min, 15min, take the sediment for direct culture separation or after enrichment and culture, then for separation and culture, for domestic and foreign use There are many kinds of culture medium for the isolation of Salmonella, but it is impossible to identify Salmonella and Proteus, and the genus Citrobacter from the colony morphology. Deng Diyi developed a new isolation medium for Salmonella, lactose lysate. Sodium dodecyl sulfate agar II (LLSII) medium, Salmonella (except Salmonella paratyphi A) can grow on the medium and form a red or orange characteristic colony with a central black edge. The bacteria of the genus Proteus and Citrobacter are inhibited by the formation of hydrogen sulfide (H2S) to form yellow colonies. Therefore, the non-salmon bacteria producing hydrogen sulfide which interferes with the isolation of Salmonella can be distinguished from the colony morphology. The identification of Salmonella is complicated. At present, more than 2,000 serotypes have been found in the world. 201 serotypes have been found in China, and new serotypes are still being discovered. Antiserum is often used as the "O" antigen. Identification, and then using antiserum for "H" antigen identification, in recent years, phage lysis test, DNA hybridization and polymerase chain reaction (PCR) and other techniques for Salmonella serotype identification.

3. Serological examination

The patient's serum can be used for agglutination test or enzyme-linked immunosorbent assay (ELISA) with a bacterial antigen or subunit antigen prepared from a known Salmonella strain to detect whether the serum contains specific antibodies, generally in the onset 1~ After 2 weeks, there is a higher antibody titer. If the double serum is checked, the second titer is increased by 4 times or more, and the diagnosis can be confirmed. However, due to the general clinical laboratory, the Salmonella antigen type Limited, it is more prone to missed detection, a certain Salmonella-specific antigen test is more helpful to confirm the diagnosis, such as Keller et al. established two mouse hybridoma cells capable of secreting Salmonella enteritidis IgG antibody, prepared by Monoclonal antibody is used as ELISA to detect Salmonella enteritidis in specimens. It has the advantages of high specificity and high sensitivity. As long as there are 10 pathogens in the specimen, it can be tested positive.

4. Molecular biology testing

In recent years, DNA probes and PCR have been used to detect Salmonella DNA, and preliminary studies have shown that PCR detection has high specificity and sensitivity.

For example, pathogenic bacteria can be measured in joint effusion.

Diagnosis and identification of other Salmonella infections

diagnosis

1. Epidemiological data Patients often have a history of suspected contaminated food due to the onset of illness. The same eater has a collective illness in a short period of time. The food is often uncooked livestock (pig, cow, sheep) or poultry (chicken, goose, duck). Meat and eggs, or other food contaminated with such food.

2. Clinical manifestations within 1 to 2 hours after eating suspicious food, sudden acute gastroenteritis symptoms, first abdominal pain, nausea, vomiting, followed by diarrhea, often accompanied by chills or chills, high fever, body temperature up to 40 ° C, stool at first It is rare, and the stool turns into a yellow water sample after a few diarrhea. The smell is strong, and the amount is more, each with less pus and blood. In addition, Salmonella infection can also appear as typhoid, sepsis or local suppurative infection.

3. Laboratory inspection

(1) Blood: The number of white blood cells in the peripheral blood is mostly in the normal range, and there is also an increase or decrease. When a local suppurative infection occurs, the number of white blood cells in the blood increases, while those who resemble typhoid fever often decrease.

(2) Bacterial culture: Gastroenteritis type can be cultured from vomit, feces, and suspicious foods to isolate pathogenic bacteria, including Salmonella typhimurium, Salmonella enteritidis, Salmonella choleraesuis, Salmonella typhimurium and Astragalus membranaceus Bacterial infections are more common. Studies have shown that the positive rate of rectal swab culture is higher, typhoid type, sepsis type can be cultured from blood, pathogens are isolated, and some cases can be cultured from local suppurative lesions or secretions. For pathogens, for patients with acute gastroenteritis, the fecal specimens can be simultaneously inoculated on a strongly selective SS agar medium and a weakly selective MacConkey medium. After 37 ° C overnight, pick up suspected colonies that do not ferment lactose and inoculate them. Cultured on trisaccharide iron medium and serologically typed. For patients who have been treated with antibacterial drugs or in the late stage of the disease, because the amount of Salmonella in their feces is already small, sometimes false negatives may occur with the above direct culture method. As a result, in order to increase the positive rate of culture, 0.5% selenite broth or tetrasulfonate broth can be used as a microbial agent, and about 1 g of stool specimens can be inoculated to 10 m. l Incubation agent, placed at 37 ° C overnight, and then transferred to the above medium for culture, Beijing Epidemic Prevention Station introduced phosphate buffer protein sputum water as an enrichment medium, inoculated specimens after 37 ° C, culture 5 ~ The effect of obvious enrichment can be achieved in 6h. The growth ability of different serotypes of Salmonella in various selective enrichment media is quite different. At present, there is no ideal enrichment medium for various kinds. Salmonella can achieve the effect of enrichment in the process, such as 0.5% selenite broth can have good enrichment effect on Salmonella typhimurium, Salmonella paratyphi A, and Salmonella choleraesuis, sheep abortion Salmonella and the like have the effect of inhibiting growth. In the selective enrichment culture, the culture temperature is increased to 43 ° C, and the culture is carried out for 18 to 24 hours. In addition to Salmonella typhimurium, the selection effect of the enrichment medium can be obviously enhanced. It has strong inhibitory effect on Escherichia coli, Proteus, Pseudomonas and non-pathogenic bacteria which do not ferment lactose, so that more pure colonies appear on the culture plate, which is easier to separate and identify further strains. Blood, urine The method for isolating Salmonella in specimens such as pus and the method for isolating Salmonella from fecal specimens is basically the same. Separating Salmonella from blood can extract 5 ml of venous blood from the patient and immediately inoculate 0.5% to 1% of 50-100 ml. Glucose bile broth or glucose broth enrichment solution, cultured at 37 ° C, daily inoculated with platinum ring to inoculate the selective medium or blood agar medium, usually continuous inoculation for 3 days, if necessary, continuous 2 weeks after inoculation, the isolation of Salmonella from urine, sputum, serosal cavity, pus, can be centrifuged first, 3000r / min, 15min, take the sediment for direct culture separation or after enrichment culture and then separate There are many kinds of culture media for the isolation of Salmonella at home and abroad, but it is impossible to identify Salmonella and Proteus, and the genus Citrobacter from the colony morphology. Deng Diyi et al developed a new Salmonella isolation. The medium, lactose lysine sodium dodecyl sulfate agar II (LLSII) medium, and Salmonella (except Salmonella paratyphi A) can grow on the medium and form a central black edge red or Orange Characteristic colonies, and the bacteria of the genus Proteus and Citrobacter are inhibited by the characteristics of hydrogen sulfide (H2S) to form yellow colonies. Therefore, from the colony morphology, the hydrogen sulfide-producing which interferes with the isolation of Salmonella can be produced. The identification of Salmonella is more complicated than that of non-Salmonella. At present, more than 2,000 serotypes have been found in the world. 201 serotypes have been found in China. New serotypes are still being discovered, often with antiserum. "O" antigen identification, and then using antiserum for "H" antigen identification, in recent years, phage lysis test, DNA hybridization and polymerase chain reaction (PCR) and other techniques for Salmonella serotype identification.

(3) Serological examination: the patient's serum can be used for agglutination test or enzyme-linked immunosorbent assay (ELISA) with a bacterial antigen or subunit antigen prepared from a known Salmonella strain to detect whether the serum contains specificity. Antibodies, generally appear 1 to 2 weeks after the onset of high antibody titer, if double serum test, the second titer is 4 times or more increased, can be clearly diagnosed as the disease, but, due to general clinical The Salmonella antigens in the laboratory are limited, so it is prone to missed detection. It is helpful to confirm the diagnosis by certain Salmonella-specific antigens. For example, Keller has established two strains that can secrete Salmonella enteritidis IgG antibodies. Hybridoma cells, using the prepared monoclonal antibody as an ELISA to detect Salmonella enterica in the specimen, have the advantages of high specificity and high sensitivity. As long as there are 10 pathogenic bacteria in the specimen, the test is positive.

(4) Molecular biological detection: In recent years, DNA probes and PCR have been used to detect Salmonella DNA. Moreover, PCR detection has high specificity and sensitivity.

Differential diagnosis

1. Differential diagnosis of gastroenteritis

(1) Staphylococcus aureus food poisoning: Staphylococcus aureus can produce exotoxin during growth. It can cause food poisoning after eating. The incubation period is short. After 1 to 5 hours after eating, nausea and headache will occur after 2~3 hours. Then, there is severe abdominal pain and vomiting. Most of the body temperature is normal or only low fever. The stool is discharged several times a day. It is yellow watery and stench. Usually, the amount is small, and there may be a sense of urgency. Serious cases may also be caused by frequent diarrhea. Dehydration, stool and residual food bacteria can grow with S. aureus.

(2) Vibrio parahaemolyticus food poisoning: Vibrio parahaemolyticus, also known as halophilic bacteria, incubation period of 6 ~ 12h, first abdominal pain, chills, fever, followed by severe diarrhea, vomiting, yellow stool Water sample or blood water sample, can have more mucus and pus and blood, strong odor, defecation several times a day, each time more, more likely to cause dehydration, can also have a sense of urgency, stool and residual food bacteria culture can be There is Vibrio parahaemolyticus growth, which is more common in residents or tourists in coastal areas.

(3) E. coli food poisoning: the pathogen is toxin-producing or invasive Escherichia coli, commonly known as Escherichia coli, with an incubation period of 2 to 20 hours, usually 4 to 6 hours, first appearing loss of appetite, abdominal pain, nausea, and then appear Diarrhea, but less vomiting, stools are mostly yellow watery, can be mucus pus and blood, have a foul smell, several times a day, each time more, more no urgency, severe cases can cause dehydration, stool and residual food Bacterial culture can produce toxin-producing or invasive E. coli growth.

(4) Clostridium botulinum food poisoning: eating food poisoning caused by meat contaminated with Clostridium botulinum, the incubation period is 2 to 72 hours, mostly 12 to 36 hours, often suddenly onset, first Generalized weakness, weakness, headache, dizziness, blurred vision, diplopia, eye muscle spasm, severe cases followed by pronunciation, swallowing and difficulty breathing, normal temperature or only low fever, consciousness is always clear, may be lighter Gastrointestinal symptoms, such as nausea, constipation, bloating, etc., diarrhea is rare, and the remaining food bacteria can be cultured with Clostridium botulinum.

(5) Proteus poisoning: the incubation period is generally 4 ~ 12h, first abdominal pain, nausea, fever, followed by vomiting, diarrhea, stool yellow water, several times a day, each time more, can cause dehydration, often no urgency Sense, stool and residual food bacteria culture can have Proteus growth.

(6) Bacterial dysentery: the incubation period is longer, usually 1 to 2 days, often with symptoms of systemic poisoning, such as fever, headache, abdominal pain, diarrhea and general malaise, less vomiting, frequent stools, often more than 10 times However, each time the amount of bowel movements is small, it is a mucus pus-like blood sample, which is obviously heavy after urgency. The faeces are cultured with Shigella, commonly known as dysentery bacilli.

(7) Cholera: The incubation period is generally 1 to 3 days. There are often epidemiological clues to be found. Typical cases are vomiting and vomiting. The vomiting and diarrhea is rice bran-like, dehydration is obvious, caused by OI group Vibrio cholerae. No fever, abdominal pain; caused by non-OI group Vibrio cholerae, often have fever, abdominal pain, and can occur bacteremia, causing parenteral damage, vomiting and diarrhea culture can have Vibrio cholerae growth.

(8) chemical poisons or biotoxin gastroenteritis: chemical poisons, such as arsenic, mercury, organic phosphorus, etc., biotoxic substances, such as gastroenteritis, fish gall, pufferfish and other gastroenteritis have a corresponding food eating history, incubation period Shorter, usually for a few hours, in addition to gastrointestinal symptoms, the patient has clinical manifestations of multiple organ damage such as liver, heart, kidney, nerves, etc., vomiting and diarrhea and residual food can detect poison.

(9) Others: The disease needs to be differentiated from viral gastroenteritis, curvular enteritis and Yersinia enteritis.

2. Differential diagnosis of typhoid and sepsis type typhoid fever, paratyphoid compared with other Salmonella infections, typhoid fever, paratyphoid fever longer, more serious illness, typhoid fever, paratyphoid fever has relatively slow pulse, rose rash, can occur intestinal Complications such as bleeding, intestinal perforation, and other Salmonella infections are rare, typhoid fever, paratyphoid serum serum reaction is positive, blood, bone marrow, stool culture may have typhoid or paratyphoid bacillus growth, sepsis can often find the primary infection lesions, The total number of white blood cells and neutrophils are mostly increased, and pathogenic bacteria can be isolated from blood culture.

3. Differential diagnosis of localized purulent infection type Local suppurative infection caused by Salmonella and local suppurative infection caused by other bacteria are difficult to distinguish from each other in clinical practice. It is necessary to isolate pathogenic bacteria by pus culture of local lesions. Only after the identification can be made.

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