PRODUCTION OF HEMOLYSIN AND ENTEROTOXIN BY AEROMONAS-JANDAEI AND AEROMONAS-TROTA STRAINS AFTER ANIMAL PASSAGE

Five Aeromonas jandaei and 12 Aeromonas trota isolates were tested for the production of haemolysin and enterotoxin, and the correlation bet ween these two properties. The majority (10 isolates) of the strains p roduced beta-haemolysis. The titres of haemolytic activity for both sp ecies were 8-64 HU/mL. In the initial ileal loop test, only two (A. tr ota) of the 17 isolates produced enterotoxin. One each of these 2 A. t rota strains was beta-haemolytic and non-haemolytic, The remaining iso lates of A. trota and A, jandaei included alpha-, beta-and non-haemoly tic strains, and failed to cause any fluid accumulation in the initial tests, but did so after one-to-five sequential passages through the r abbit ileal loops, Three alpha- and 4 non-haemolytic strains switched over to the production of beta-haemolysis when they showed the positiv e ileal loop reaction, However, on repeated subcultures or on storage in the laboratory, all of them reverted back to their original alpha- or non-haemolytic character and no longer produced enterotoxin.