Diagnosis of typhoid fever

Laboratory confirmation of diagnosis

The etiological diagnosis of typhoid fever is established exclusively based on laboratory test results. The clinical presentation only allows for suspecting the infection and initiating differential diagnostic workup.

The basis of diagnosis is the bacteriological method—isolation of the pathogen culture. Depending on the stage of the disease, various biological materials are collected from the patient:

• Blood (blood culture);
• Urine (urine culture);
• Stool (stool culture).

During the convalescence stage or for retrospective diagnosis, serological methods are used. Confirmation is provided by a reliable increase in the titer of specific antibodies when examining the patient's paired sera.

Differential diagnosis in the first week

Due to the similarity of the early clinical presentation, typhoid fever is differentiated from a number of infections. First of all, paratyphoid A and B and generalized salmonellosis are ruled out. They are characterized by less pronounced intoxication, a shorter febrile period, and earlier (end of the 1st week), more abundant rash appearance. In the blood test for these infections, unlike typhoid fever, leukocytosis with preserved eosinophils is detected.

Also in the early stages, differential diagnosis is performed with:

• Influenza. Characterized by an acute onset, short fever (up to 5 days), and myalgia. Severe pain in the frontal and temporal regions, and pain upon eye movement are typical. Tracheitis symptoms join by the 2nd day. Viral antigens can be detected in nasal swabs (ELISA).
• Epidemic typhus. Epidemiological history (pediculosis) is of key importance. The onset is acute, accompanied by insomnia, severe headache, and productive psychosis. Positive endothelial symptoms (Chiari-Avtsyn, Rosenberg) and Govorov-Godelier sign are revealed. The roseolopetechial rash on the trunk appears on days 4–5 of the disease. Antibodies to Rickettsia prowazekii are detected in the blood.
• Malaria. Associated with endemic regions. Fever takes the form of periodic paroxysms with severe chills and sweats. Splenomegaly and hepatomegaly develop early. The diagnosis is confirmed by finding plasmodia in a thick blood smear.

Differential diagnosis from the second week

At later stages (from the 2nd week), the spectrum of probable diagnoses changes. Typhoid fever must be distinguished from:

1. Infectious mononucleosis (EBV infection). The disease proceeds with prolonged fever, enlargement of the liver and spleen, pronounced tonsillitis (up to necrotic), and lymphadenopathy (especially of the occipital nodes). An important diagnostic marker is the appearance of an abundant rash upon taking ampicillin. Laboratory findings reveal atypical mononuclear cells, absolute lymphocytosis, and IgM antibodies to the Epstein-Barr virus.
2. Brucellosis. The disease is associated with the consumption of raw meat and dairy products and contact with animals. It manifests with prolonged high fever, polyadenopathy, and hepatosplenomegaly. A specific feature is that the patient maintains satisfactory well-being and performance for a long time. The diagnosis is confirmed by isolating blood and bone marrow cultures, and the Burnet test.

In addition, tularemia, yersiniosis, leptospirosis, sepsis, and miliary tuberculosis are ruled out.

Principles of therapy and physical activity regimen

Patients are subject to mandatory hospitalization in an infectious diseases hospital. The basis for preventing fatal complications (intestinal perforation and intestinal bleeding) is a strict physical activity regimen combined with antibacterial therapy:

• Strict bed rest: maintained until the 7th day of normal temperature. Physical exertion (including coughing) is strictly limited.
• Allowed to sit: only from the 7th to the 10th days of apyrexia.
• Allowed to walk: from the 11th day of normal temperature.

Etiotropic therapy implies a prolonged continuous course of antibiotics until the 10th day of normal temperature. It is advisable to use fluoroquinolones (ciprofloxacin), aminoglycosides (gentamicin), or 3rd-4th generation cephalosporins (ceftriaxone, cefotaxime). Due to the duration of the course, metronidazole is added to prevent complications caused by anaerobic flora. Diet No. 4 is prescribed, and from the 5th week, the patient is transferred to table No. 13.

Discharge rules and follow-up observation

Discharge criteria are strictly regulated by the timing of temperature normalization (apyrexia). Patients who received antibiotics are discharged no earlier than the 21st day of normal temperature. If etiotropic treatment was not performed—on the 14th day, which corresponds to the 6th week of the disease and the end of the repair of typhoid ulcers.

Before discharge, sanitation control is performed:

• Materials: 3-fold stool and urine culture (with a 2-day interval) + 1-fold bile examination (via duodenal sounding).
• Conditions: collection begins no earlier than 2 days after the complete discontinuation of antibiotics.

After the hospital, the patient is under medical observation for 3–4 months. Bacteriological control is carried out monthly, and bile examination and serology in indirect hemagglutination assay (IHA) are performed in the 4th month. For decreed groups (food industry, water supply), the rules for work clearance are much stricter.

Class and exam questions

What else to study on this topic

• Management features of bacterial carriers and decreed persons
• Specific endothelial symptoms of epidemic typhus
• Infectious-toxic shock in typhoid fever
• Complications of typhoid fever: intestinal perforation and hemorrhage

Other topics in the "Acute Intestinal Infections" section

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