Modern features of legionellosis

BACKGROUND: Community-acquired Legionella pneumonia, classified as atypical pneumonia, is an important problem worldwide. Late initiation of etiotropic therapy for Legionnaires’ disease worsens the prognosis and increases the risk of death.

AIM: To clinically and epidemiologically characterize Legionnaires’ disease using data on its incidence in the Krasnodar region and to attract the attention of doctors to its timely diagnosis and the prescription of adequate etiotropic therapy.

MATERIALS AND METHODS: A hospital cohort of 26 patients who were hospitalized between 2017 and 2022 was studied for legionellosis, which was confirmed in the laboratory by the detection of Legionella antigen in the urine using immunochromatography.

RESULTS: The Krasnodar region is characterized by a sporadic incidence of legionellosis, which tends to increase in periods with high average humidity. Cases of legionellosis are recorded throughout the year, with peaks in summer and winter. The rise in incidence shifts annually and follows the month with the highest rainfall and average monthly temperature >20°C. Severe and moderate courses of legionellosis typically occur in men aged >50 years, with comorbid pathology and accompanied by lung damage of varying severity levels. Some patients may experience diarrhea (11.5%) and transient liver and kidney dysfunction. The nature of lung damage, such as polysegmental pneumonia, does not have clear clinical differential diagnostics, which makes early diagnosis difficult. An epidemiological anamnesis indicating contact with aerosol water, soil, and air conditioning systems has important diagnostic significance. Seeking specialized medical care after the 7th day of illness increases the risk of developing severe disease with complications.

CONCLUSIONS: In severe community-acquired pneumonia, the epidemiological history must be considered, kidney and liver function should be assessed, a urine test must conducted for Legionella antigens, and early empirical therapy with fluoroquinolones and macrolides must be initiated.