Laboratory diagnosis of food poisoning

Laboratory methods and etiology

Due to the short duration of bacterial food poisoning (BFP) and the high efficacy of the applied therapy, complex and expensive laboratory tests are often not performed. In most routine cases, the diagnosis is established clinically. However, specific methods are used in the presence of special indications.

To confirm the diagnosis of botulism, the key test is the botulinum toxin neutralization test, which is performed using a bioassay.

Food poisoning of viral etiology is most commonly caused by rotaviruses, caliciviruses, noroviruses (including Norwalk and Norwalk-like viruses), as well as enteric adenoviruses. An epidemiological marker of such infections is their occurrence as group outbreaks in organized childcare settings. If a viral origin of the disease is suspected, laboratory tactics depend on the timing:

• In the first days (early stages), the patient's coprofiltrate is analyzed. Latex agglutination test is used to detect viral antigens.
• In later stages, diagnostics shift to serological methods: blood is examined using ELISA to detect specific antibodies.

Clinical symptoms and differential diagnosis

Clinical manifestations of viral gastroenteritis include moderate and short-term intoxication. Signs of gastroenteritis develop, while marked dehydration is not typical, and vomiting predominates over diarrhea. An important distinguishing feature is that abdominal pain is not typical for this condition.

In botulism, specific symptoms come to the foreground: dryness of the oral mucosa (which occurs without thirst), elevated blood pressure, and absence of fever. By the end of the first day, ophthalmoplegic symptoms join: mydriasis, impaired accommodation and convergence, diplopia, ptosis, and strabismus.

Differential diagnosis should be performed with gastroenteritis of other etiologies (campylobacteriosis, escherichiosis). It is especially important (primarily in the gastritis variant of BFP) to exclude acute surgical and somatic pathology:

• Myocardial infarction.
• Acute appendicitis.
• Acute cholecystitis and pancreatitis.
• Mesenteric vascular thrombosis.
• Ectopic pregnancy.

Indications for hospitalization and baseline therapy

Hospitalization in an infectious diseases hospital is carried out strictly according to clinical and epidemiological indications. In other cases, outpatient treatment is permitted. Clinical indications include a severe course and the presence of severe comorbid somatic pathology. Epidemiological indications include illnesses in patients from organized groups and decreeed professions (food service workers, trade workers, water supply station personnel, and staff of preschool childcare facilities).

General treatment principles imply the avoidance of etiotropic therapy. The foundation consists of diet, regimen, detoxification, and rehydration. Diet therapy aims at chemical and mechanical sparing of the stomach and intestines: diet No. 4 is prescribed in the acute period, and as diarrhea subsides, diet No. 13.

At the initial stage, gastric lavage until clear water is indicated. A 2% sodium bicarbonate solution or 0.1% potassium permanganate solution is used (volume on average 3 liters, temperature 18–20°C). The procedure is contraindicated in coronary heart disease with angina pectoris, peptic ulcer disease, cerebral atherosclerosis, and hypertension with high blood pressure values.

Rehydration, sorbents, and outcomes

Enterosorption (polyphepan, activated charcoal, enterodez in standard dosages) is used to eliminate unabsorbed toxins.

Rehydration therapy is performed exclusively with polyionic solutions:

• Glucose-salt mixtures (Regidron, Citraglucosolan) are used orally.
• Solutions such as "Quartasol", "Acesol", "Lactasol", and "Trisol" are prescribed parenterally.

Colloid solutions are not indicated. The use of probiotics during the convalescence period is also not indicated, as bacterial food poisoning develops with a non-inflammatory type of diarrhea.

Discharge of convalescents is carried out only after complete clinical recovery. Specific prophylaxis is absent; non-specific prophylaxis consists of veterinary-sanitary, anti-epidemic, and sanitary-hygienic measures.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Features of ophthalmoplegic symptoms in severe forms of botulism
• Gastroenteritic variant of the course of bacterial food poisoning
• Differential diagnosis of food poisoning and acute abdominal surgical pathology
• Organization of sanitary-hygienic and veterinary-sanitary measures

Other topics in the "Acute Intestinal Infections" section

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