Toxin production by Aeromonas spp. from different sources.

One hundred and eleven isolates of Aeromonas from water and from human sources were identified to species level and tested for the production of cytotoxin. These results were correlated with the source of each isolate and, for those from human faeces, with the clinical history of diarrhoea. A. caviae predominated in water, comprising 16 of 32 isolates; only one isolate from water was A. sobria. In human faecal samples 21 of 76 isolates were A. sobria; this was a significant difference. Cytotoxin producing strains were significantly more common in patients with no known cause for their gut symptoms. It is concluded that gastro-enteritis caused by Aeromonas is related to species and to production of cytotoxin.