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Legionellosis
Last reviewed: 20.11.2021
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Legionellosis (Pittsburgh pneumonia, Pontiac fever, Fort-Bragg fever) is a group of diseases caused by bacteria of the genus Legionella, with an aerosol mechanism of transmission of the pathogen, characterized by fever, intoxication, respiratory tract infection, kidney and CNS.
Legionella pneumophila most often causes pneumonia with signs of extrapulmonary pathology. Diagnosis requires a special plant environment, carrying out serological tests or PCR analysis. Treatment of legionellosis is carried out by doxycycline, macrolides or fluoroquinolones.
ICD-10 codes
- A48.1. Legionnaires' disease.
- A48.2. Disease of legionnaires without pneumonia (Pontiac fever).
What causes legionellosis?
The first appearance of this microorganism was registered in 1976 at the convention of the American Legion, hence the name "Legionnaires' disease". Extrapulmonary infection is called a Pontiac fever. These bacteria can be found in dirty or raw water. Production containers for water storage, including conditioning units based on water cooling, enhance the growth of MO. The spread of infection most likely occurs through aerosols of drinking water.
Extrapulmonary symptoms of legionellosis most often occur in hospitalized patients and most often affect the heart. Other manifestations of the infection include the central nervous system, liver and intestines. Immunocompromised patients, smokers, elderly people and patients with chronic lung diseases are primarily affected.
What are the symptoms of legionellosis?
Legionnaires' disease begins with a flu-like syndrome. Acute fever, chills, weakness, myalgia, headache or confusion occur. Often there are symptoms of legionellosis, such as: nausea, profuse watery diarrhea, abdominal pain, cough and arthralgia. Pulmonary manifestation can include shortness of breath, pleural pain and hemoptysis.
What's bothering you?
How is legionella diagnosed?
Diagnosis of Legionella is based on examination of sputum or washing water of the bronchi. The culture of the blood is unreliable. Slow growth in a nutrient medium can delay MO identification for 3-5 days. Often direct fluorescence staining of sputum specimens or bronchial washings with labeled antibodies is used. In addition, it is possible to carry out PCR with DNA probing. The urine antigen test has a sensitivity of 70% and a specificity of 100% 3 days after the onset of the first symptoms. However, this test determines only Legionella pneumophila (1 serogroup) and is not capable of determining non-pneumophilic legionella. A coupled study for antibodies in an acute period or a period of recovery can give a delayed diagnosis. A fourfold increase or antibody titer in the acute period above 1:12 is considered diagnostic. Chest X-ray usually reveals nonspecific changes, such as infiltrates and pleural effusion.
How is legionellosis treated?
Legionellosis is treated with doxycycline, macrolides and fluoroquinolones. The recommended treatment is the appointment of any pulmonary fluoroquinolone (intravenously or orally) for 7-14 days. In acute infections, rifampin can be added. Among people who have no other pathology, mortality in this disease is low, but it can reach 50% for nosocomial outbreaks of infection.