Pulmonary Infections Due to Legionella pneumophila in Immunocompromised Patients

Authors: DEMET KAYA, SİNAN ERGİNEL, MUZAFFER METİNTAŞ, ZEKİ ÜSTÜNER, İRFAN UÇGUN, NECLA ÖZDEMİR

Abstract: The numbers of immunocom-promised individuals increase as programmes for organ transplantation and chemotherapy of malignant disease advance. Pulmonary infections, which progress rapidly, are one of the major clinical problems in these groups. This study was designed to evaluate the microbiology of pneumonia in immunocompromised patients and to determine the role of Legionella pneumophila. Immunocompromised patients receiving antineoplastic chemotherapy, diagnosed as pneumonia with clinical and radiographic findings and routine laboratory tests were included in the study. For microbiological diagnosis, expectorated sputum was cultured for L. pneumophila. In addition to standard bacterial, fungal and mycobacterial media, specimens were examined microscopically. Direct flourescent antibody (DFA) assay was used for antigen detection of L. pneumophila. By indirect flourescent antibody (IFA) assay the sera of the patients were screened for L. pneumophila. Of 74 sputum samples, 7 (9.5%) specimens yielded L. pneumophila. The other isolates were Escherichia coli (n:3), Enterobacter sp. (n:2), Aspergillus sp. (n:3), Mycobacterium tuberculosis (n:3), Staphylococcus aureus (n:1), yeasts (n:10), Nocardia sp. (n:2) and flora members (n:43). Antibiotic supplemented media and acid treatment was found superior for the isolation of L. pneumophila. Direct microscopic evaluation was necessary to support the culture results. DFA assay had 85% sensitivity and 100% specificity. Of 3 sera screened by IFA for L. pneumophila antibodies, 2 had the titres 1/256, indicating the disease. Our results showed that L. pneumophila has an important role among the respiratory pathogens in immunocompromised patients, and it may be useful if techniques for isolation and identification of this pathogen are added to routine culturing programmes.

Keywords: L. pneumophila, immunocompromised patients, pulmonary infection, diagnosis.

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