Detection of Legionella DNA by PCR of whole-blood samples in a mouse model

Abstract

A detection system for Legionella DNA in blood samples based on the PCR was developed and evaluated in A/J mice with experimentally induced Legionella pneumonia. Primers were designed to amplify a 106 bp DNA fragment of the 16S rRNA gene specific to Legionella species. The PCR system could detect clinically relevant Legionella species including Legionella pneumophila, Legionella micdadei, Legionella bozemanae, Legionella dumoffii, Legionella longbeachae, Legionella gormanii and Legionella jordanis. The sensitivity of the PCR system was 20 fg extracted DNA. In the mouse model, the blood PCR was compared with results obtained by PCR on bronchoalveolar lavage fluid (BALF) samples, cultures of blood and BALF and detection of Legionella urinary antigen. Blood PCR was positive until 8 days after infection, while BALF PCR became negative on day 4. These results indicate that PCR using blood samples may be a useful, convenient and non-invasive method for the diagnosis of Legionella pneumonia.

Molecular genetic methods in the diagnosis of lower respiratory tract infections

“…In a guinea pig model, peripheral leukocytes had a greater PCR positivity rate than plasma or urine samples (61), but evaluation of this sample type in humans is limited to a single case report where leukocyte samples remained PCR positive for up to 56 days after onset of symptoms (67). Whole blood samples were useful in a mouse legionella pneumonia model, whereby legionellae were detected in blood samples for a longer period than in bronchoalveolar lavage fluid (68). The evaluation of throat swab samples is largely limited to one study that found positive samples from five of six patients with legionellosis (69).…”

In vivo efficacy of sivelestat in combination with pazufloxacin againstLegionellapneumonia

“…Anaesthetized mice were inoculated with the bacteria at 50 l/mouse (1 × 10 8 cfu/mouse) intratracheally [20].…”