Legionella pneumophila is involved in more than 95% cases of severe atypical pneumonia. Infection is mainly by inhalation the indoor aerosols through the water-coolant systems. Because some Legionella strains may be viable but not culturable, therefore, Taq polymerase, DNA amplification and semi-nested-PCR were carried out to detect Legionella-specific 16S-rDNA sequence. For this purpose, 1.5 l...

Legionella pneumophila has frequently been isolated from patients with Legionnaires disease and in several instances also from epidemic-related environmental samples. A selective medium was developed and used successfully to isolate Legionella pneumophila and Legionella-like organisms from environmental specimens animal inoculation methods. Legionella pneumophila is a Gram-negative, facultative...

During its life cycle, Legionella pneumophila alternates between a replicative and a transmissive state. To determine their contributions to L. pneumophila differentiation, the two ppGpp synthetases, RelA and SpoT, were disrupted. Synthesis of ppGpp was required for transmission, as relA spoT mutants were killed during entry to and exit from macrophages. RelA, which senses amino acid starvation...

Our aim was to investigate the occurrence and identity of Legionella spp. in Dutch tap water installations using culture, real-time PCR and sequence analysis. The PCR assays used were a 16S rRNA gene based PCR with both a Legionella species specific probe and a L. pneumophila specific probe and a L. pneumophila-specific PCR based on the sequence of the mip gene. A total of 357 water samples fro...

Legionellosis can be diagnosed by PCR using sputum samples. In this report, the methods of nine laboratories for 12 sputum samples with Legionella pneumophila and Legionella longbeachae are compared. We conclude that (i) liquefaction prevents PCR inhibition, (ii) the employed mip gene PCRs detected L. pneumophila only, and (iii) the 16S rRNA gene PCR detected both Legionella species and is pref...

Various Legionella isolates from different sources and origins were analysed by orthogonal field alternation gel electrophoresis of NotI cleaved genomic DNA. The genome of L. pneumophila Philadelphia I, the original isolate of the epidemics in 1976, exhibits only five NotI fragments. Two virulent derivatives, derived from L. pneumophila Philadelphia I, which were obtained by prolonged passage o...

We introduce a new image cytometer design for detection of very small particulate and demonstrate its capability in water analysis. The device is a compact microscope composed of off-the-shelf components, such as a light emitting diode (LED) source, a complementary metal– oxide–semiconductor (CMOS) image sensor, and a specific combination of optical lenses that allow, through an appropriate sof...

The Legionella pneumophila dotA gene is required for intracellular growth of the bacterium in macrophages. In this study, a structure-function analysis of the DotA protein was conducted to elucidate the role of this protein in L. pneumophila pathogenesis. Translational fusions of dotA to the Escherichia coli phoA and lacZ genes indicated that DotA is an integral cytoplasmic membrane protein wit...

IFN receptor signaling induces cell-autonomous immunity to infections with intracellular bacterial pathogens. Here, we demonstrate that IFN-inducible guanylate binding protein (Gbp) proteins stimulate caspase-11-dependent, cell-autonomous immunity in response to cytoplasmic LPS. Caspase-11-dependent pyroptosis is triggered in IFN-activated macrophages infected with the Gram-negative bacterial p...

The formation and release of outer membrane vesicles (OMVs) is a phenomenon of Gram-negative bacteria. This includes Legionella pneumophila (L. pneumophila), a causative agent of severe pneumonia. Upon its transmission into the lung, L. pneumophila primarily infects and replicates within macrophages. Here, we analyzed the influence of L. pneumophila OMVs on macrophages. To this end, differentia...