Legionellosis

Legionellosis ( Legionnaires disease, Pittsburgh pneumonia, Pontian fever, Legionella infection) - acute infectious disease caused by various types of legionella, characterized by fever, expressed by a general intoxication, severe course, lung damage, central nervous system, digestive organs. In the US legionella caused up to 1.5% of all acute pneumonia.

Etiology, pathogenesis. Legionella are gram-negative bacteria that are widespread and persistently retained in the environment (in water up to 1 year). Infection occurs aerogenously by inhaling the smallest droplets of infected water (shower facilities, air conditioners, etc.). Legionella are highly sensitive to erythromycin, levomycetin, ampicillin, insensitive to tetracycline and completely insensitive to penicillin and cephalosporins. Gateways of infection are the lower parts of the respiratory tract. The most common are middle-aged and elderly people; The disease is facilitated by smoking, alcohol use, diabetes, the use of immunosuppressants, AIDS. During the decay of microbes, endotoxin is released, which causes damage to a number of organs and systems. In severe cases, an infectious-toxic shock develops that occurs with respiratory and cardiovascular insufficiency, hypoxia, respiratory acidosis.

Symptoms, course. The incubation period is 2-10 days (usually 5-7 days). The disease begins acutely. A high fever is accompanied by chills. Rapidly growing general weakness, weakness, muscle pain. From the first days there are painful coughs, stitching pains in the chest. The signs of pneumonia are revealed, the respiratory rate reaches 30-40 in 1 min. There may be vomiting, loose stools. The CNS is affected (dizziness, light-headedness, confusion). Tachycardia is marked, BP is lowered. A hemorrhagic syndrome may develop. In severe conditions, respiratory and cardiovascular insufficiency rapidly builds up, an infectious-toxic shock develops. Death comes to the end of 1-and the disease does not last.

Legionellosis does not always take the form of pneumonia. The so-called Pontiac fever is characterized by a short-term rise in temperature (2-5 days), moderately pronounced general intoxication. Some bronchitis and pleurisy can be detected in some patients, but pneumonia is absent. There are no lethal outcomes with this form of the disease.

About logmonellosis it is necessary to think at development of a serious pneumonia in an unusual season (the end of summer) at men of average and advanced age at presence predisposing factors (smoking, an alcoholism, a diabetes, etc.). It is also important that there is no therapeutic effect from antibiotics commonly used in pneumonia (penicillin, streptomycin, tetracycline). Differentiate is necessary from other pneumonias. To confirm the diagnosis use bacteriological and serological methods.

Treatment. The most effective erythromycin is 0.4-0.5 g 4-6 times a day until stable temperature normalization. In severe cases, erythromycin phosphate can be given intravenously 2-3 times a day for 0.2 g. Efficacy increases with the combination of erythromycin and rifampicin.

The prognosis is serious. In the US, the mortality rate reached 20%; When using erythromycin lethality about 4%.

Prevention. Disinfection of water, bathrooms, shower screens, control of air conditioning. Patients are placed in separate wards. Conduct current disinfection of sputum and other discharge of the patient.