Epidemiology of clinical and environmental Pseudomonas aeruginosa strains

296 strains collection of Pseudomonas aeruginosa isolated from the hospital environment (100), marine water (119) and mineral water (77) were identified and confirmed by 26 biochemical, physiological and metabolic tests. This identification was deepened by three epidemiological markers: antibiotyping, serotyping and pyocinotyping. The biochemical and epidemiological studies showed that the clinical strains and the mineral water ones are closely related: (i) the dominant hospital serotypes are O: 1, O: 4, O: 10 and O: 11. Those of mineral water are O: 1, O: 10, the poly-agglutinable and the non-agglutinable. Marine strains are clearly characterised by the predominance of 0: 6 serotype (95,8%). The pyocinotyping suggests a clear separation of the clinical strains dominated by the pyocinotypes P10, P3 and P1 and the marine strains represented by the pyocinotypes P31, P77, P84 and the non-pyocinotypable. The clinical strains are the most resistant to antibiotics. Those of mineral water have an intermediate resistance and the marine strains are the most sensitive. The epidemiological markers allow us to define the strains variability in hospitals and environment. All the results suggest a clear segregation of the P. aeruginosa isolated both from hospital environment and marine water whereas the mineral water strains are intermediate between the two groups and are more related with the clinical strains.