Methodology Issues of Legionella Pneumonia Diagnosis in Medical Institutions (Part 2)

Clinical Microbiology and Antimicrobial Chemotherapy. 2013; 15(3):166-172

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Type
Journal article

Objective.

To use algorithm of microbiologic and epidemiologic methods when detecting two or more cases of legionellosis in the medical institution, in accordance with the international guidelines and to assess its efficacy.

Materials and Methods.

A total of 76 hematological patients with pneumonia and acute respiratory failure were tested for legionellosis using bronchoalveolar lavage (BAL) fluid culture and Legionella urinary antigen test between December 2010 and January 2013. Water samples obtained from the institution’s hot water supply system were tested for Legionella by the standard microbiology method. Dresden Panel and multilocus sequence typing (MLST) according to the STB protocol were performed for comparison of clinical Legionella isolates with isolates from the institution’s hot water supply system.

Results.

Diagnosis of legionellosis was confirmed in 8 of 76 patients (10.5%). The diagnosis was made by positive BAL culture for Legionella pneumophila in 7 patients: serogroup 1 (3 patients), serogroup 3 (3 patients), and serogroup 9 (1 patient). Hot water samples culture showed the presence of L. pneumophila serogroup 2 and 3 strains. No isolates of L. pneumophila serogroup 1 were found in hot water samples. MLST confirmed that the L. pneumophila serogroup 3 isolate from the water supply system was identical to the L. pneumophila serogroup 3 isolates obtained from 3 patients. All of the isolates were ST 87.

Conclusions.

The modern surveillance algorithm for two or more cases of legionellosis associated with one facility was successfully used in Russia for the first time. MLST and the monoclonal antibodies panel showed that 3 of 7 cases of legionellosis were caused by different strains of L. pneumophila serogroup 1 being absent in the institution’s water supply system and were not associated with hospital stay. For other 3 cases, the clinical isolates were confirmed to be identical to the L. pneumophila serogroup 3 isolate from the institution’s water supply system. This algorithm appears to be effective in determining source of Legionella infection in healthcare institutions as well as different community facilities (hotels, business centers, malls, etc.).

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