[Rarely encountered, atypical and new species of enterobacteria].

The article characterizes "rare", atypical and new individualized representatives of Enterobacteriaceae family. Classification approach is formulated which makes it possible to subdivide enterobacteria into three groups according to frequency of isolation, genetic determination and degree of atypicality. Schemes are presented for differential diagnosis for correct carrying out laboratory investigations and adequate interpretation of bacteriological assays results.