Open AccessA putative heat-labile enterotoxin expressed by strains of Aeromonas media
Author(s) -
Deepika Singh
Publication year - 2000
Publication title -
journal of medical microbiology/journal of medical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 117
eISSN - 1473-5644
pISSN - 0022-2615
DOI - 10.1099/0022-1317-49-8-685
Subject(s) - enterotoxin , microbiology and biotechnology , aeromonas , vibrio cholerae , vibrionaceae , vibrio , catfish , fish <actinopterygii> , biology , bacteria , chemistry , food science , escherichia coli , biochemistry , fishery , genetics , gene
Fifteen isolates of Aeromonas media (seven from diarrhoeal stools, four from water and four from superficial skin ulcers of catfish) were examined for enterotoxin production. Ten of these isolates (six diarrhoeal, one from water and three from fish) caused accumulation of fluid in the initial rabbit ileal loop (RIL) tests. Isolates from diarrhoeal stools and fish caused relatively more fluid accumulation than those from water. Those strains that caused little or no fluid accumulation in the initial experiments became enterotoxin producers after one passage through RILs, regardless of source, and also showed gradual enhancement of fluid outpouring after each subsequent passage. Inocula of c. 1 x 10(4) viable cells and 0.25 ml of culture filtrate (CF) caused fluid accumulation similar to that of toxigenic Vibrio cholerae 569B. The enterotoxic factor(s) were inactivated when held at 56 degrees C for 20 min or 65 degrees C for 10 min and showed biological activity over a wide range of pH values. These results suggest that strains of A. media, whether from diarrhoeal stools, water or infected fish, are potentially enterotoxigenic and may have the potential to produce a heat-labile and pH-stable diarrhoeagenic factor in the same way as other known heat-labile and pH-stable enterotoxins.