The following forms and variants of the course of salmonellosis are distinguished:
- Gastrointestinal (localized) form:
1.1. gastric option,
1.2. gastroenteric option,
1.3. gastroenterocolitic variant.
- Generalized form:
2.1. typhoid variant,
2.2. septic option.
- Bacterial excretion:
For all forms and variants of the disease, the incubation period ranges from several hours to 2 days.
The gastroenteric variant is the most common form; develops sharply, several hours after infection. Manifested by intoxication and disorders of water and electrolyte balance. In the first hours of the disease, signs of intoxication predominate: fever, headache, chills, body aches. In the future, there are abdominal pains (usually of a spastic nature), localized in the epigastric and umbilical regions, nausea, repeated vomiting. Diarrhea quickly joins. The stool is initially fecal in nature, but quickly becomes watery, foamy, offensive, sometimes with a greenish tinge. The frequency of vomiting and defecation may vary, but the amount of fluid excreted is more important than the frequency for assessing the degree of dehydration. Defecation is not accompanied by tenesmus.
Despite the high body temperature, on examination, pallor of the skin is noted; in more severe cases, cyanosis develops. Tongue dry, coated with bloom. The abdomen is swollen, with palpation, a slight diffuse soreness and rumbling of the intestines can be noted. Heart sounds are muffled, tachycardia, a tendency to lower blood pressure, soft-filled pulse are noted. The flow of urine is reduced. In more severe cases, clonic seizures may develop, more often in the muscles of the lower extremities.
Gastroenterocolitic variant. The onset of the disease resembles the gastroenteric variant, but already on the 2-3rd day of the disease, the volume of stool decreases. Mucus appears in them, sometimes blood. On palpation of the abdomen, spasm and soreness of the colon is noted. The act of defecation may be accompanied by tenesmus. Thus, the clinical manifestations of this variant have many similarities with the variant of acute dysentery of the same name.
Gastric option. Observed much less often. Characterized by an acute onset, repeated vomiting and pain in the epigastric region. As a rule, the intoxication syndrome is mild, and diarrhea is absent at all. The course of the disease is short-term and favorable.
The severity of the gastrointestinal form of salmonellosis determines the severity of intoxication and the amount of water and electrolyte losses. When assessing the degree of intoxication, the level of the temperature reaction is primarily taken into account. Body temperature can be very high, in these cases, its rise is usually accompanied by a feeling of chills, headache, fatigue, body aches, anorexia. In cases of a milder course of the disease, the fever is moderate, even subfebrile.
At the same time, one of the leading conditions that determine the severity of the disease in various types of salmonellosis is the severity of water and electrolyte losses.
With the generalization of the process, a typhoid-like variant of salmonellosis, similar in clinical picture to typhoid-paratyphoid diseases, or a septic variant may develop. As a rule, the generalized form is preceded by gastrointestinal disorders.
Typhoid variant. May begin with manifestations of gastroenteritis. In the future, against the background of subsiding or disappearance of nausea, vomiting and diarrhea, an increase in the temperature reaction is observed, which acquires a constant or wavy character. Patients complain of headache, insomnia, severe weakness. On examination, the pallor of the patient’s skin is noted, in some cases, separate roseolous elements appear on the skin of the abdomen and lower chest. By the 3-5th day of the disease, hepatolienal syndrome develops. Blood pressure tends to decrease, relative bradycardia is expressed. In general, the clinical picture of the disease takes on features that are very reminiscent of the course of typhoid fever, which complicates the clinical differential diagnosis. A typhoid variant of salmonellosis is not excluded in the absence of initial manifestations in the form of gastroenteritis.
Septic option. In the initial period of the disease, manifestations of gastroenteritis can also be observed, which are subsequently replaced by prolonged remitting fever with chills and severe sweating when it decreases, tachycardia, myalgia. As a rule, hepatosplenomegaly develops. The course of the disease is long, torpid, characterized by a tendency to form secondary purulent foci in the lungs (pleurisy, pneumonia), heart (endocarditis), in the subcutaneous tissue and muscles (abscesses, phlegmon), in the kidneys (pyelitis, cystitis). Iritis and iridocyclitis may also develop.
After the transferred disease, regardless of the form of its course, some of the patients become bacterial excretors. In most cases, Salmonella shedding ends within 1 month (acute shedding); if it lasts more than 3 months, after clinical recovery it is regarded as chronic. With transient bacterial excretion, single or double sowing of Salmonella from feces is not accompanied by clinical manifestations of the disease and the formation of significant antibody titers.
The most dangerous complication in salmonellosis is infectious toxic shock, accompanied by acute edema and swelling of the brain, acute cardiovascular failure, often against the background of acute adrenal insufficiency and acute renal failure.
Edema and swelling of the brain, arising against the background of exicosis, are manifested by bradycardia, short-term hypertension, redness and cyanosis of the skin of the face and neck (“strangulated syndrome”), rapidly developing paresis of the muscles innervated by the cranial nerves. Then the increasing shortness of breath joins, and, finally, there comes a cerebral coma with loss of consciousness.
Severe oliguria and anuria is an alarming signal of the possible onset of acute renal failure. This suspicion is heightened if urine is still not excreted after blood pressure is restored. In such cases, it is urgent to determine the concentration of nitrogenous toxins in the blood. In the future, patients develop symptoms characteristic of uremia.
Acute cardiovascular failure is characterized by the development of collapse, a decrease in body temperature to a normal or subnormal level, the appearance of pallor and cyanosis of the skin, cooling of the extremities, and later – the disappearance of the pulse due to a sharp drop in blood pressure. If the adrenal glands are involved in the process (hemorrhages in them due to disseminated intravascular coagulation), the collapse is very resistant to therapeutic influences.
Diagnosis of Salmonellosis
Salmonellosis should be distinguished from many diseases accompanied by the development of diarrheal syndrome: shigellosis, escherichiosis, cholera, viral diarrheal infections, mushroom poisoning, heavy metal salts, phosphorus-organic compounds, etc. In addition, in some cases, there is a need for urgent differential diagnosis of salmonellosis from myocardial infarction, acute appendicitis, an attack of gallstone disease, thrombosis of mesenteric vessels.
The gastroenteric variant of salmonellosis is characterized by the predominance of signs of intoxication in the first hours of the disease, then the development of dyspeptic phenomena – nausea and vomiting, spastic abdominal pain, diarrhea with watery, foamy fetid stools. The gastroenterocolitic variant is distinguished by a decrease in the volume of bowel movements from the 2-3rd day of illness, the appearance in them of mucus and, possibly, blood, spasm and soreness of the colon, sometimes tenesmus. Salmonella gastritis, as a rule, develops against the background of general toxic signs of varying severity. Typhoid and septic variants of the generalized form of salmonellosis are easier to suspect if they begin with manifestations of gastroenteritis; in other cases, their differential diagnosis with typhoid fever and sepsis is extremely difficult.
Laboratory diagnostics of salmonellosis
The basis is the isolation of the pathogen by crops of vomit and feces, and in the generalized form and blood. The material for bacteriological research can also be gastric and intestinal washings, urine, and bile. With a septicopyemic variant of the disease, seeding of pus or exudate from inflammatory foci is possible. For epidemiological control of outbreaks of salmonellosis, bacteriological analysis of food residues suspected of contamination, as well as washings from dishes, is carried out. It is mandatory to use enrichment media (magnesium medium, selenite medium), several differential diagnostic media (Endo, Ploskireva, bismuth-sulfite agar), a fairly wide range of biochemical tests and a set of monovalent adsorbed O- and H-sera.
As methods of serological diagnostics, RNGA is used with complex and group salmonella erythrocyte diagnostics when staging a reaction in paired sera with an interval of 5-7 days. The minimum diagnostic antibody titer in RNGA is -1: 200. Unfortunately, serological methods in most cases are of value only for retrospective confirmation of the diagnosis.
More promising is the rapid detection of Salmonella antigens in RCA, RLA, ELISA and RIA.
To establish the degree of dehydration and assess the severity of the patient’s condition, as well as to correct the ongoing rehydration therapy, hematocrit, blood viscosity, indicators of acid-base state and electrolyte composition are determined.
Hospitalization of patients is carried out only with severe or complicated course, as well as for epidemiological indications. Bed rest is prescribed for severe manifestations of toxicosis and dehydration.
If the patient’s clinical condition allows, treatment should be started with gastric lavage, siphon enemas, and the appointment of enterosorbents (activated carbon, etc.)
In case of dehydration of the I-II degree, the appointment of glucose-salt solutions of the type “Cytroglucosolan”, “Glucosolan”, “Regidron”, “Oralit” is indicated, taking into account the deficiency of water and salts in the patient before the start of therapy, replenished with fractional frequent drinking (up to 1-1 , 5 l / h) for 2-3 hours, and further fluid loss during treatment (should be monitored every 2-4 hours).
In case of dehydration of III-IV degree, isotonic polyionic crystalloid solutions are injected intravenously by jet until the signs of dehydration shock are eliminated, and then by drip.
If necessary, additional correction of the content of K + ions is carried out – inside in the form of solutions of potassium chloride or potassium citrate, 1 g 3-4 times a day (the content of electrolytes in the blood should be monitored).
Intravenous administration of macromolecular colloidal preparations (rheopolyglucin, hemodez, etc.) for detoxification can be carried out only after correction of water-electrolyte losses. With severe metabolic acidosis, additional intravenous administration of 4% sodium bicarbonate solution may be required under the control of acid-base state indicators.
In addition, indomethacin may be prescribed to relieve signs of intoxication in the gastrointestinal form of salmonellosis. The drug is prescribed in the early stages of the disease, 50 mg 3 times for 12 hours.
In the gastrointestinal form, the use of antibiotics and other etiotropic drugs is not indicated in most cases. They must be used for generalized salmonellosis (fluoroquinolones 0.5 g 2 times a day, chloramphenicol 0.5 g 4-5 times a day, doxycycline 0.1 g / day, etc.). It is advisable to prescribe complex enzyme preparations (enzistal, festal, mexase, etc.).
The diet of patients in the acute period of the disease corresponds to table No. 4 according to Pevzner, after the cessation of diarrhea, table No. 13 is prescribed.
Prevention of Salmonellosis
The leading role in the prevention of salmonellosis belongs to the combined epidemiological and epizootic surveillance carried out by the veterinary and sanitary-epidemiological services. The veterinary service constantly monitors the morbidity of animals, the frequency of infection of feed and meat products, carries out microbiological monitoring of the serological structure of the secreted Salmonella and their biological properties. The Sanitary-Epidemiological Service monitors the incidence of people, its tendencies and characteristics in a certain period of time and in a given territory, monitors the serotypic structure of the pathogen excreted from people and from food, and studies the biological properties of Salmonella. Of great importance is the development of reliable diagnostic methods and standardization of procedures for recording and notifying cases of disease, as well as control over food products entering the market, especially those imported from other regions of the country or from abroad. The combined analysis of the incidence of the population and the epizootic process of salmonellosis among animals and poultry allows timely epidemiological diagnostics, planning and organizational and methodological support of preventive and anti-epidemic measures.
The basis for the prevention of salmonellosis among humans is veterinary and sanitary measures aimed at ensuring proper conditions in the process of slaughtering livestock and poultry, adhering to the slaughtering regime of animals, processing technology for carcasses, preparing and storing meat and fish dishes. Of great importance are regular selective control of feed and feed ingredients, the planned implementation of disinfection and deratization measures at meat processing plants, food and raw materials warehouses, refrigerators, and vaccination of farm animals. In public catering and personal home practice, it is necessary to strictly observe the sanitary and hygienic rules for cooking, separate processing of raw meat and cooked products, conditions and terms of storage of finished food. A signal to carry out special anti-epidemic measures is an increase in the number of excretions of Salmonella strains of the same serovar, the appearance of new or an increase in the number of excretions of Salmonella, rarely found in a given territory of serovars: an increase in the proportion of strains resistant to antibiotics, the emergence of an outbreak of salmonellosis. For the prevention of nosocomial infection, all requirements of the sanitary and hygienic and anti-epidemic regime in medical institutions should be observed. Persons who first come to work in preschool institutions and treatment-and-prophylactic institutions, in food industry enterprises and institutions equated to them are subject to mandatory bacteriological examination. There are no specific prophylaxis means.
Activities in the epidemic focus
Hospitalization of patients is carried out according to clinical indications. Compulsory hospitalization and dispensary observation of those who have recovered are subject only to employees of food enterprises and persons equated to them. Discharge from the hospital is carried out after clinical recovery and a single bacteriological examination of feces, carried out 2 days after the end of treatment. Food industry workers and persons equated to them are subjected at discharge after negative results of a 2-fold bacteriological examination. Persons who do not emit the pathogen are allowed to work. When a bacterial carrier is established within 3 months, these persons, as chronic carriers of Salmonella, are suspended from work in their specialty for a period of at least one year. Children who are chronic carriers of Salmonella are not allowed in day nurseries (baby homes). Such children attending kindergartens and general education schools, including boarding schools, are allowed into collectives, but they are prohibited from being on duty at the catering facilities.
In relation to persons who have communicated with a patient with salmonellosis, if the patient is left at home, separation is not used. Employees of food and similar enterprises, children attending children’s institutions, as well as children from orphanages and boarding schools are subjected to a single bacteriological examination. In case of nosocomial infection with salmonellosis, patients, and in case of illness of children – and mothers caring for them, are transferred to an infectious diseases hospital; in case of group diseases, it is possible to temporarily organize a special department on site with the involvement of an infectious disease specialist to serve patients. Admission of new patients to this department is stopped until the outbreak stops.
Disinfection measures in the departments are carried out as in other acute intestinal infections, paying special attention to the disinfection of patient secretions, bedding and dishes. Systematic processing of patient care items, baths, cleaning equipment, etc. In children’s departments, changing tables are subject to disinfection after each use. The only means of emergency prophylaxis in the focus of infection in the event of prolonged nosocomial outbreaks of salmonellosis is the therapeutic bacteriophage of salmonella group ABCDE.