PSEUDOMONAS-AERUGINOSA AS A CAUSE OF INFECTIOUS DIARRHEA

Pseudomonas aeruginosa is not generally considered a cause of infectio us diarrhoea. However, it was the predominant organism isolated from t he faeces of 23 unrelated, hospital outpatients investigated in the co urse of a year for persistent (> 1 week duration) diarrhoea. To invest igate the possible aetiological role of P. aeruginosa, these patient h istories were reviewed and a selection of their faecal isolates were i nvestigated in vitro (n greater than or equal to 10) and in vivo (n = 2) for virulence. The patients had a mean age of 60 years, were receiv ing antibiotics and/or had an underlying illness. Extensive microbiolo gical investigations identified no other potential or recognized enter opathogen in the faeces of 20 of these patients. More than 40 % of the isolates tested were able to adhere to HEp-2 cells and exhibited twit ching motility (type IV pill), properties indicative of their ability to colonize the human intestine. Cytotoxic activity was demonstrated i n bacterium-free cell supernatants of over 80 % of isolates; supernata nts of four isolates tested in infant mice were weakly enterotoxigenic . Two isolates intragastrically inoculated into clindamycin pre-treate d rats established persistent infections and induced signs and symptom s of enteritis. Overall these findings suggest that P. aeruginosa can cause diarrhoea particularly in immunodeficient individuals.