Cellular envelope phospholipids from Legionella lytica.

The composition of phospholipids from the cellular envelope of Legionella lytica grown on artificial medium was determined by two-dimensional thin-layer chromatography. Phosphatidylcholine, phosphatidylethanolamine, and phosphatidyl-N-monomethylethanolamine were the predominant phospholipids, while diphosphatidylglycerol, phosphatidylglycerol, and phosphatidyl-N,N-dimethylethanolamine were present at low concentrations. A trace amount of lipids carrying glycosyl residues was also observed. The fatty acids and their distribution in individual phospholipids were characterized using liquid chromatography/mass spectrometry (LC/MS), matrix-assisted laser desorption ionization-time of flight, and gas chromatography/MS methods. The characteristic feature of L. lytica phospholipids was the presence of an unbranched chain (which differentiates this bacterium from Legionella pneumophila) and branched iso and anteiso fatty acids as well as cis-9,10-methylenehexadecanoic acid. According to spectroscopic LC/MS data, the localization of saturated and unsaturated fatty acid residues on phosphorylglycerol was determined. Some aspects of the significance of phosphatidylcholine, one of the main phospholipids in L. lytica, are addressed and taxonomic implications of the data are discussed.

Monitoring Legionella species in hospital water systems. Link with disease and evaluation of different detection methods.

The aim of this work was to evaluate three currently available isolation methods for Legionella using water samples and swabs of a single pediatric hospital water system. Additionally, high risk patients were screened for the presence of Legionella pneumophila antigen in urine. Fifteen water samples and 11 swab samples were collected from distal sites at 18 sampling locations. The International Standard Method (PN-ISO11731-2) based on membrane filtration and direct culture of bacteria on selective media were compared with amoebic co-culture. The numbers of legionellae detected exceeded 10(2) cfu/100 ml in 50% of the samples. All the positive samples contained L. pneumophila SGs 2-14. Urine samples were obtained from 57 immunosuppressed children and screened for the presence of L. pneumophila serogroup (SG) 1 antigen by Legionella urinary antigen EIA. Of the 57 urine samples tested for the presence of Legionella pneumophila SG 1 antigen, none were positive. Our results highlight the value of combined membrane filtration and amoebic co-culture methods in detecting viable L. pneumophila strains. Direct plating of 0.2 ml water is a useful screening method for samples containing large bacterial amount.

[Pathogenesis and virulence determinants of the family Legionellaceae]. / Patogeneza i czynniki wirulencji paleczek z rodziny Legionellaceae.

Legionellae are Gram-negative obligate intracellular parasites of unicellular animal organisms, some of which are sometimes able to cause an acute and sever pneumonia in humans. Legionellae, are capable of surviving for long periods in water when between hosts. Their adaptation to these quite diverse environments seems to be accomplished by morphological and biochemical pathway changes. It has been well established that humans coexisted with these bacteria for a long period of time, and it is only recently that our industrial technology provided these organisms with the means of causing infection. This review describes the invasion process and the life cycle of Legionellae in both protozoan and mammalian cells. Our understanding of the infection cycle of Legionellae is primarily based on observations by transmission and scanning EM and by contrast phase and fluorescence microscopy. The identification of virulence determinants by molecular techniques is also discussed. The bacteria enter the host cell mainly by coiling phagocytosis and reside within unique phagosomes which, during the first hours of infection, are isolated from the endosomal pathway. Within the protected vacuole the mature infectious forms of Legionellae convert to replicative forms that no longer express virulence traits. Evidence is provided on how the biogenesis of the replication niche is determined. The virulence factors that arrest phagosome maturation during intracellular replication are also described. The status of our current knowledge on the means by which Legionellae successfully infect the host cells to cause disease is discussed.