Virulence factors and infection ability of Pseudomonas aeruginosa isolates from a hydropathic facility and respiratory infections.

AIMS: To compare the virulence pool and acute infection ability of Pseudomonas aeruginosa isolates from a hydropathic facility, used to treat respiratory conditions by inhalation of untreated natural mineral water, with clinical isolates from respiratory infections. METHODS AND RESULTS: Pseudomonas aeruginosa isolates from a hydropathic facility and from respiratory infections were typed by pulsed-field gel electrophoresis. Nonclonal representatives of each population were selected. 18 virulence-encoding genes were screened by polymerase chain reaction and statistically compared by multiple correspondence analysis. Homogeneous distribution of genes between populations but higher genetic association in aquatic isolates was observed, as well as distinct virulence pool according to location in the water system. Acute infection ability of selected isolates from each population, in Galleria mellonella model, showed lower LD50 of the majority of the hydropathic isolates and significant variations in LD50 of biofilm isolates from different equipments. CONCLUSIONS: Hydrotherapy Ps. aeruginosa isolates present similar virulence to isolates from respiratory infections. Hydrotherapy users may be exposed to different microbiological risks when using different treatment equipments. SIGNIFICANCE AND IMPACT OF THE STUDY: Twenty-one million people use hydropathic facilities in Europe, and the majority present risk factors to pneumonia. This study demonstrates the health risk associated with this practice. Revision of European regulations should be considered.

HLA antigens and lymphocytes in proliferative vitreoretinopathy.

An immunohistopathological study was performed on 33 epiretinal membrane specimens obtained during vitreoretinal surgery from patients with rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy (PVR). Immunofluorescence and immunoperoxidase methods were used to detect major histocompatibility complex or HLA antigens and immunocompetent cells, and to identify the cellular and the extracellular component of the proliferative tissue. The following antigens were detected in epiretinal membranes: cytokeratin in 18 (of 18 cases studied for this antigen), glial fibrillary acidic protein in 20 (of 20), vimentin in 20 (of 20), actin in 16 (of 18), fibronectin in 20 (of 20), macrophage CD68 in 16 (of 18), leukocyte common antigen in 12 (of 18), T-cell CD45R in 13 (of 22), HLA-ABC in 27 (of 33), HLA-DR in all the 33 membranes and HLA-DR alpha chain in 32 of 33 membranes. We observed the presence of macrophages and of an activated T-cell population in PVR membranes. HLA-DR antigen expression was found on pigmented and nonpigmented epithelial cells and on mononuclear cells in all epiretinal membranes. The HLA-DR expression on retinal pigmented epithelial cells could play a role in triggering a local immune response in PVR. These findings suggest the involvement of immunological phenomena and probable interactions between the immune system and peptide growth factors.

[Microscopic quantification of fluorescein distribution in retinas of normal and diabetic rats]. / Quantification microscopique de la distribution de fluorescéine dans la rétine chez des rats normaux et diabétiques.

To identify more precisely the site and the nature of the abnormality of the Blood-Retinal Barrier (B.R.B.) in diabetes, quantitative fluorescence microscopy was used to measure time-dependent changes of fluorescence in ocular tissues of normal and diabetic rats, after intravenous fluorescein injection. Fluorescein distribution across the retinal layers was studied in control and streptozotocin diabetic rats at 5, 30 and 60 minutes after dye injection. Fluorescein intensities of choriocapillaris and retina were compared with plasma fluorescein levels. The results show a B.R.B. dysfunction in diabetic rats arising from abnormal leakage of fluorescein into the retina. After 60 minutes there was a greater fluorescence intensity localized to the inner retinal layers, consistent with a probable inhibition or saturation of active transport mechanisms for dye removal through the retinal vessels.