Diagnosis of Legionella Pneumophila by Direct Fluorescent Antibody (Dfa) Technique in Bronchoalveolar Specimens of Pneumonia Patients Referring to Medical Centers in Isfahan, 2002

Wide and universal distribution of Legionnaires’ disease, abundance of reports about its prevalence and Pontiac fever from different countries, unresponsiveness to conventional antibiotic therapy in a number of pneumonia patients and the lack of any report about it in Iran directed us to perform this project. Legionnaires’ disease is seen in sporadic and epidemic form and the most prevalent cause is legionella pnuemophilia which produces a severe disease in vulnerable individuals with a high fatality rate (50-80%). It is also considered as one of the most fatal nasocomial infections. In the present research for isolating and detecting of L. pneumophila, bronchoalveolar specimens of patients were examined using culture and DFA methods. After 3-5 days of incubation at 370C, and humidity (about 95%), thin, convex and round colonies with blue-gray to blue-green appearance developed. Slides were prepared from these colonies and stained with Gram and Gimenez methods which displayed Gram –negative, small successive coccobacilli. Statistical analysis were performed by a software (SPSS, v10) using Fisher exact and McNemar Tests. From among the 96 bronchoscopic specimens, 4 strains of Gram negative bacilli were isolated. Further investigations by means of biochemical tests and specific DFA revealed that they were L.pneumophila. In vitro drug resistance and sensitivity tests of Legionella showed that these bacteria were sensitive to Erythromycin, Riphampicin, Gentamycin, Doxycycline and Tubramicin, the sensitivity being more pronounced against Erythromycin than others. The above–mentioned organisms were resistant to Tetracycline and Ampicillin. The Fisher exact Test revealed that there is no correlation between frequency of L.pneumophila and the sex of patients (P value= 0.72). McNemar Test was performed and the results revealed that there is no significant difference between the results obtained by culture and DFA tests (P value= 1). L.pneumophila has no correlation with the sex of patients. According to the results obtained by McNemar test, DFA method can be used for rapid detection of L.pneumophila, although further studies with larger quantity of specimens need to be performed to substantiate results.