[Microbiological diagnosis of microorganisms tentatively designated as "SP organisms"].

The authors describe the biochemical characteristics of two strains described as "SP organism". This microorganism incertae sedis resembles from the biochemical aspect (oxidase+, mannite-, dextrose+ with gas) the species Pasteurella aerogenes; contrary to the latter it does not break down urea and differs also as regards the morphology of colonies, which on blood agar are coarser; it also has a higher content of G + C in DNA than Pasteurella. It is a pathogen of rodents. The authors describe two isolates, the first is obviously an incidental finding from the faeces of a 5-year-old girl who was symptom-free, the second is from the contents of an abscess of a nutria. For comparison also biochemical characteristics of known aerogenic pasteurellae and Pasteurella-like strains are given.