Salmonellosis is an infectious disease of the digestive system resulting from infection with bacteria of the genus Salmonella, accompanied by severe intoxication and dehydration, sometimes occurring as typhus, or with septicemia. The most dangerous in terms of salmonellosis are thermally poorly processed eggs, dairy and meat products. The course of salmonellosis can occur according to the gastrointestinal or generalized variant, bacterial excretion without clinical manifestations is possible. The diagnosis of salmonellosis is made when salmonella is detected in the feces and vomit of the patient.
Salmonellosis is an infectious disease of the digestive system resulting from infection with bacteria of the genus Salmonella, accompanied by severe intoxication and dehydration, sometimes occurring as typhus, or with septicemia.
Salmonella is a genus of gram–negative, motile, facultatively anaerobic, rod-shaped microorganisms. Relatively stable in the environment. They can remain viable in water for up to 5 months, in soil for up to one and a half years, in meat for up to six months, in bird carcasses for up to a year or more. About 20 days are preserved in milk, a month in kefir and four in butter. In cheese, salmonella can remain alive for up to a year, 3-9 months in egg powder and 17-24 days on eggshells. Salmonella die after 5-10 minutes at a temperature of 70 ° C, Can withstand boiling for a while if they are in the thickness of a large piece of meat. When cooking eggs, they die after 4 minutes. In milk and meat products, salmonella is not only preserved, but also actively multiplies, while not affecting the organoleptic properties of the products. Microorganisms are quite resistant to salting and smoking, and when frozen, they increase the duration of their life. Currently, resident (otherwise – hospital) strains of salmonella with a high degree of resistance to antibiotic therapy and disinfectants have been identified.
The reservoir and source of salmonellosis is livestock, poultry, and some wild animals. In animals, the disease can occur both with clinical manifestations and asymptomatic. Healthy animals do not get sick with salmonellosis, individuals with weakened immunity are prone to this. Salmonella enter the bloodstream of such animals and seed organs and tissues. A person becomes infected when caring for sick animals, slaughtering them, eating infected animal products. Birds with salmonellosis can pollute objects of the environment and food with droppings. In some cases (certain types of pathogen), the source of infection may be a person. Animals are contagious for several months, a person can transmit the infection in the period from a few days to three weeks, sometimes the carrier persists for years.
Salmonellosis is transmitted by the fecal-oral mechanism mainly by food. The main importance in the epidemiology of salmonellosis is played by meat and dairy products, poultry eggs. The waterway of infection is realized in the case of salmonella ingress into drinking water sources for livestock in livestock farms. The contact-household route often has an important epidemiological significance in cases of nosocomial infections. In urban conditions, it is possible to implement an air-dust path of infection.
People have a high susceptibility to salmonellosis. The severity of the infection that has developed depends on a complex of factors, both external (the number of pathogens that have entered the body, their antigenic composition and biological characteristics) and internal (the state of the protective systems of the human body, concomitant pathologies, in particular the digestive system). The infection is most severe in infants (especially premature infants) and the elderly. Postinfectious immunity is unstable, it persists for no more than a year.
According to the clinical picture and the degree of spread, the infectious process is divided into gastrointestinal, generalized salmonellosis and bacterial excretion. The gastrointestinal form differs in localization into variants: gastritic, gastroenteritic and gastroenterocolitic.
Generalized salmonellosis can occur in the form of two variants: typhoid and septic. Bacterial excretion can be acute, chronic and transient.
The incubation period of salmonellosis can last from several hours to two days. Clinical manifestations depend on the variant of the disease. The most common form is the gastroenteritic variant of salmonellosis. It is characterized by general intoxication and violation of water-salt metabolism. The disease begins acutely, with an increase in temperature and an increase in signs of intoxication (headache, muscle aches, weakness). Then there is spastic pain in the abdomen with predominant localization in the upper abdomen and umbilical region, nausea and frequent vomiting. Diarrhea soon joins, fecal masses quickly acquire a watery, foamy character, fetid, sometimes their greenish tint is noted. Diarrhea and vomiting have different frequency depending on the severity of the disease. The abundance of secreted fluid during vomiting and defecation leads to the development of dehydration.
Physical examination reveals pallor of the skin, despite fever, cyanosis is sometimes noted, the tongue is dry and covered with plaque, bloating. When palpation in the abdomen, rumbling is noted, moderate soreness. When listening to the heart tachycardia, the tones are muted. Pulse of soft filling, tendency to arterial hypotension. Moderate oliguria is often noted. With severe dehydration, convulsions may develop, mainly in the lower extremities.
With the gastroenterocolitic variant, by the second or third day, the volume of bowel movements decreases, mucus and blood veins may be detected in the feces. Palpation of the abdomen reveals soreness and spasm of the large intestine, defecation may be accompanied by tenesmus. The gastritic variant has the most mild and short-term course, it is relatively rare. It is also characterized by an acute onset, less pronounced intoxication, repeated vomiting. The pain is localized mainly in the epigastric region, diarrhea does not develop. In the gastrointestinal form of salmonellosis, the severity is determined by the severity of intoxication and dehydration syndromes. The degree of intoxication is usually characterized by body temperature, which can vary from subfebrility to severe fever.
The generalized form can proceed according to a typhoid-like variant, while initially gastroenteral phenomena are often noted. Subsequently, as nausea, vomiting and diarrhea subside, fever and signs of intoxication increase (headache, insomnia, pronounced weakness), while the fever becomes permanent or undulating. When examining a patient, elements of hemorrhagic rash on the skin may sometimes be noted, on day 3-5, hepatosplenomegaly is detected. Moderate arterial hypotension and relative bradycardia are characteristic. The clinical picture resembles that of typhoid fever.
The septic variant of salmonellosis also often begins with a gastrointestinal clinic, followed by severe persistent remitting fever, tachycardia, chills and intense sweating when the temperature drops. There is a hepatolienal syndrome. The disease proceeds heavily, for a long time, can contribute to the development of secondary foci of purulent inflammation in the lungs, kidneys and bladder (pyelonephritis, cystitis), endocarditis, abscesses and phlegmon. Sometimes there is an inflammation of the iris.
After undergoing salmonellosis, regardless of its form, some patients continue to secrete the pathogen (bacterial excretion) for up to a month. If bacterial excretion is delayed for more than three months, it is recognized as chronic. Severe complications with a high probability of death include infectious and toxic shock, which is accompanied by edema of the lungs and brain, cardiovascular, renal and adrenal insufficiency. Generalized forms are fraught with the development of purulent complications.
For diagnosis, the pathogen is isolated from vomit and feces (in generalized forms, the pathogen is detected in the blood tank). Sometimes bacteria can be isolated from the washing waters of the stomach and intestines, bile. To identify the pathogen, sowing is carried out on nutrient media. Serological diagnostics is performed using RPH, ELISA.
The degree of dehydration is determined based on the analysis of data on hematocrit, blood viscosity, acid-base state and electrolyte balance. With the development of complications of salmonellosis, it is necessary to consult a cardiologist, urologist, nephrologist and other specialists, depending on the type of complication.
Patients with severe course or prone to complications are subject to hospitalization, in other cases, treatment is carried out at home. It is advisable to initially implement measures for gastric and intestinal lavage (siphon enemas, enterosorbents). Then the water-salt balance is corrected by taking rehydration measures. Dehydration of the first and second degree is corrected by frequent fractional ingestion of saline solutions. A more severe degree of dehydration may require intravenous infusion therapy with isotonic polyionic solutions.
Detoxification therapy with colloidal solutions or 10% dextran solution is carried out only after the restoration of water-electrolyte homeostasis. Signs of severe metabolic acidosis are an indication for the appointment of intravenous sodium bicarbonate.
Antibiotic therapy is indicated for a generalized form of the disease. Prescribe drugs of the fluoroquinolone group, chloramphenicol, doxycycline. For the treatment of gastrointestinal forms of the disease, antibiotics are used only in cases of infection resistant to other therapeutic measures. In the gastrointestinal form, a good effect is given by the appointment of enzyme preparations (pancreatin, dry bile). In the acute period of the disease, the patient is prescribed diet No. 4, after the intestinal manifestations subside – No. 13.
The general prevention of salmonellosis includes measures to ensure sanitary and hygienic conditions during the maintenance, slaughter of livestock and poultry, processing of carcasses and animal products, cooking dishes from them at catering establishments and food industries. As well as measures to control the morbidity of farm animals and birds. Individual prevention consists in careful culinary processing of animal products, compliance with the shelf life of food.
Measures of specific prevention of salmonellosis (vaccination) are not provided due to the antigenic heterogeneity of the pathogen and the instability of immunity. Emergency prevention in the focus of infection in nosocomial outbreaks is carried out with the help of a therapeutic salmonella bacteriophage.