Study on the pathogenicity of some Nocardia spp isolated from tap water of Ismailia City, Egypt.

All actinomycetes isolated from canal water, Ismailia water plant and tap water were identified into 5 genera. All Nocardia isolates were identified into 3 species. Two of which, Nocardia transvalensis and Nocardia otitidus-caviarus were recorded in tap water. These species are pathogenic for human kind and animals. The pathogenicity of these isolates was tested on Swiss Albino mice. Symptomatic changes and death of mice inoculated with Nocardia suspension were recorded. The main symptoms were erythema, enduration and inflammation together with abcesses and an increase in the size of the spleen (spleenomegally). It is concluded from these experiments that: i) All Nocardia species isolated from tap water are pathogenic, at least for mice, ii) these isolates could present health hazards to human kind and needs an urgent investigation.