Salmonellosis

Salmonellosis is an acute zoonotic infectious disease with a fecal-oral mechanism of transmission of the pathogen, characterized by predominant damage to the gastrointestinal tract, the development of intoxication and dehydration.

Nontyphoidal salmonellae, primarily Salmonella Enteritidis, primarily cause gastroenteritis, bacteremia, and focal infection. Symptoms of salmonellosis include diarrhea, high laxative fever, and signs of focal infection. Diagnosis of salmonellosis is based on blood culture, stool culture from lesions. Treatment of salmonellosis, if indicated, is with trimethoprim-sulfamethoxazole or ciprofloxacin, with surgical treatment of abscesses, vascular lesions, bones, and joints.

Epidemiology of salmonellosis

The reservoir and source of the infectious agent are sick animals: cattle, small cattle, pigs, horses, poultry. In them, the disease is acute or in the form of a carrier state. A person (sick or a carrier) can also be a source of S. typhimurium. The transmission mechanism is feco-oral. The main route of transmission is food, through animal products. Infection of meat occurs endogenously during the life of the animal, as well as exogenously during transportation, processing, and storage. In recent years, there has been a significant increase in the incidence of S. enteritidis associated with the spread of the pathogen through poultry meat and eggs. The water route of transmission mainly plays a role in the infection of animals. The contact-household route (through hands and instruments), as a rule, occurs in transmission of the pathogen in medical institutions. The greatest risk of salmonellosis infection is in children of the first year of life and individuals with immunodeficiency. The airborne dust route plays a large role in the spread of infection among wild birds. The incidence of salmonellosis is high in large cities. Cases of the disease are registered throughout the year, but more often in the summer months due to worse food storage conditions. Sporadic and group incidence is observed. People are highly susceptible to the pathogen. Post-infection immunity lasts less than a year.

[ 1 ], [ 2 ], [ 3 ], [ 4 ]

What causes salmonellosis?

The most common cause of salmonellosis is Salmonella enteritidis. These infections are common and a serious problem in the United States. Many serotypes of Salmonella enteritidis have names and are loosely referred to as separate species, which is not the case. The most common species of Salmonella in the United States are: Salmonella thyphimurium, Salmonella heidelberg, Salmonella newport, Salmonella infantis, Salmonella agona, Salmonella montevidel, Salmonella saint-paul.

Human salmonellosis occurs through direct and indirect contact with infected animals, their products, and their secretions. Infected meat, poultry, raw milk, eggs, and products made from them are the most common sources of salmonella. Other possible sources of infection include infected pet turtles and reptiles, carmine red dye, and marijuana.

The following diseases predispose to salmonellosis: subtotal gastrectomy, aphthous hydria (or taking antacids), sickle cell anemia, splenectomy, louse-borne relapsing fever, malaria, bartonellosis, liver cirrhosis, leukemia, lymphoma, HIV infection.

All Salmonella serotypes can cause the clinical syndromes described below, either individually or together, although each serotype is often associated with a specific syndrome. Enteric fever is caused by Salmonella parathifi types A, B, and C.

Asymptomatic carriage may also occur. However, carriers do not play a significant role in the occurrence of gastroenteritis outbreaks. Continuous excretion of pathogens with stool for a year or more is observed in only 0.2-0.6% of those who have had non-typhoid salmonellosis.

What are the symptoms of salmonellosis?

Infection caused by salmonella may clinically manifest as gastroenteritis, typhoid-like form, bacteremic syndrome and focal form.
Gastroenteritis begins 12-48 hours after salmonella is ingested. Nausea and abdominal cramps appear at first, then diarrhea, fever, and sometimes vomiting.

Stool is usually watery, but can be mushy semi-liquid, occasionally with mucus and blood. Salmonellosis is not severe and lasts 1-4 days. Sometimes a more severe and prolonged course occurs.

The typhoid-like form is characterized by fever, prostration and septicemia. Salmonellosis proceeds in the same way as typhoid fever, but more easily.

Bacteremia is uncommon in patients with gastroenteritis. However, Salmonella choleraesuis, Salmonella thyphimurium heidelberg, and others can cause a fatal bacteremic syndrome lasting 1 week or more with prolonged fever, headache, weight loss, chills, but rarely diarrhea. Patients may have transient episodes of bacteremia or evidence of focal infection (eg, septic arthritis). And patients with disseminated Salmonella infection without risk factors should be tested for HIV infection.

Focal salmonellosis may occur with or without bacteremia. In patients with bacteremia, the gastrointestinal tract (liver, gallbladder, appendix, etc.), endothelium (atherosclerotic plaques, aneurysms of the iliac or femoral artery or aorta, heart valves), pericardium, meninges, lungs, joints, bones, genitourinary tract, and soft tissues may be affected.

Sometimes solid tumors with abscess formation are observed, which become a source of salmonella bacteremia. Salmonella choleraesuis, Salmonella thyphimurium are the most common cause of focal infection.

How is salmonellosis diagnosed?

Salmonellosis diagnostics is based on the isolation of the pathogen from feces and other materials. In bacteremia and local forms, blood culture is positive, but stool culture is negative. Stool samples are stained with methylene blue, leukocytes are often detected, indicating an inflammatory process in the colon - colitis.

How is salmonellosis treated?

Gastroenteritis is treated symptomatically, with plenty of fluids and a gentle diet. In uncomplicated cases, antibiotics are undesirable, as they prolong the period of excretion of the pathogen from feces. However, in the elderly, children and HIV-infected patients with an increased risk of mortality, antibiotic treatment is indicated. Antibiotic resistance in non-typhoid salmonella is even more common than in S. typhi.

Salmonellosis of moderate and severe localized form is treated by prescribing Enterix, two capsules three times a day for 5-6 days; chlorquinaldol 0.2 g 3 times a day for 3-5 days.

Trimethoprim-sulfamethoxazole 5 mg/kg (as trimethoprim) every 12 hours for children and ciprofloxacin orally every 12 hours for adults. In patients with a normal immune system, salmonellosis is treated for 3-5 days, while patients with AIDS may require longer treatment. Systemic or focal forms of the disease are treated with antibiotics in the same doses as for typhoid fever. Persistent bacteremia usually requires continued therapy for 4-6 weeks. Abscesses should be incised. Then antibiotic therapy for 4 weeks. Infections of aneurysms, heart valves, and bones or joints usually require surgical treatment and prolonged antibiotic therapy.

In asymptomatic carriers, the infection usually resolves on its own and antibiotics are rarely needed. In special cases (e.g., food industry or health care workers), an attempt to eliminate the carrier state can be made with ciprofloxacin 500 mg every 12 hours for 1 month. To confirm the elimination of Salmonella, follow-up stool cultures are required for several weeks after completion of treatment.

How to prevent salmonellosis?

Salmonellosis can be prevented by preventing contamination of food from animals and humans. All cases should be reported.

Specific prevention of salmonellosis

There is no specific prevention of salmonellosis.

Non-specific prevention of salmonellosis

Veterinary and sanitary supervision of slaughter of livestock and poultry, carcass processing technology, preparation and storage of meat dishes. Compliance with sanitary and hygienic and anti-epidemic standards at trade and public catering establishments.