Molecular Detection of Legionella in Clinical Samples

Target sequences of the hitherto developed Legionella-specific PCR assays were the 16S rRNA gene and the 5S rRNA gene of Legionella spp. and the mip gene of L. pneumophila. Due to the nature of infection, materials from the deep respiratory tract, such as bronchial alveolar lavage fluid and sputum, are the samples of choice for investigation and have been studied extensively during the last decade (Table 1). In the studies, the PCR assays consistently detected all culture-positive samples. Realtime PCR assays even allowed a diagnosis of Legionella infection within a few hours. Notably, in most studies PCR-positive samples that were negative by culture were also observed, ranging from 3% to 12% of the samples investigated.1-16-23-1 Because most of these samples were obtained from patients with a serologically confirmed Legionella infection or from patients with otherwise undefined pneumonia, a higher sensitivity of the PCR assays compared to culture can be assumed. Although all studies suffer from a small sample size, PCR may be considered the method of choice for detection of acute legionellosis, especially in patients with a higher risk of infections caused by legionellae other than L. pneumophila serogroup 1 in nosocomial settings or in certain geographical regions.

However, less than half of the patients with legion-ellosis can produce sputum, and, thus, PCR testing of other materials has been evaluated in several studies. In accordance with antigen detection assays, legionellae can be detected in urine of affected patients; however, the sensitivity was much lower than in respiratory samples and adds little to that of antigen detection assays.[11] In addition to urine, serum was evaluated in a few studies. Whereas Lindsay et al.[25] recorded positive results by PCR and probing in five out of five patients with legionellosis, others found sensitivities for serum PCR assays of only 30% to 43% in studies comprising up to 28 patients.[11] Clearly, further evaluation of nonrespiratory samples and sample types is necessary to determine their role in the diagnosis of legionellosis.

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Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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