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Chapter 13 : Specific Detection of Legionella in Samples from Patients with Community-Acquired Pneumonia by PCR and a Colorimetric Detection System (Reverse Dot Blot)
Specific Detection of Legionella in Samples from Patients with Community-Acquired Pneumonia by PCR and a Colorimetric Detection System (Reverse Dot Blot), Page 1 of 2< Previous page Next page > /docserver/preview/fulltext/10.1128/9781555815660/9781555813901_Chap13-1.gif /docserver/preview/fulltext/10.1128/9781555815660/9781555813901_Chap13-2.gif
Despite extensive efforts, the etiology of about 40 to 60% of community-acquired pneumonia remains unclear; a number of these cases are attributed to Legionella. The incidence in this group may be as high as 38%. Cultivation is still supposed to be the gold standard, but there is doubt about the sensitivity in clinical practice. Researchers established a new method for the detection of Legionella by using PCR to amplify genomic ribosomal DNA and a reverse dot blot for the detection of L. pneumophila and non-pneumophila species. The authors used a multiplex-PCR and the coamplification of human DNA (pyruvate dehydrogenase gene) as an internal control to avoid false-positive results. To avoid false-positive results, incubation with uracil-N-glycosylase was used, and for avoidance of false-negative results the coamplification of the pyruvate dehydrogenase gene was used, creating an amplificate of 185 bp in length in each PCR. The authors used the established method to investigate clinical specimens of 93 patients taken out of a prospective randomized study about the epidemiology of community-acquired pneumonia in Berlin, Germany, from 1991 to 1992. They were able to demonstrate the ability to detect Legionella using PCR in conjunction with reverse dot blotting. This method allows the enhanced detection of non-pneumophila species in addition to established methods. Interpretation of the results for the incidence of non-pneumophila infections remains controversial because of a lack of facts about pathogenity of this group and comparable results in other studies.