Incidence of Motile Aeromonas Species in Aquatic Environments of Rio De Janeiro; Brazil

Fresh and salt water samples collected in Rio de Janeiro city were analysed for the presence of motile Aeromonas species. Twenty-six out of 50 aliquots analysed (52%) were positive for Aeromonas . One hundred strains were isolated from both environments ( A. caviae , 60%; A. veronii , 14%; A. hydrophila , 1%; A. sobria , 1%; and Aeromonas sp., 24%). Minimal tests such as oxidase, motility, sensitivity to the vibriostatic agent 2,4-diamino-6,7 - diisopropylpteridine, fermentation and gas from glucose, acetoin from glucose (Voges-Proskauer), lysine decarboxylase, ornithine decarboxylase, and esculin hydrolysis were sufficient to classify the majority Aeromonas strains into species. No Aeromonas was found in nonpolluted waters but, in contrast, both fresh and salt polluted waters showed a high incidence of isolates. Most of the Aeromonas strains analysed produced hemolysin and/or heat-stable enterotoxin. The latter was produced by 73% of the A. veronii isolates.