Previous Article | Next Article ![]()
Journal of Clinical Microbiology, October 2000, p. 3785-3790, Vol. 38, No. 10
International Centre for Diarrhoeal Disease Research,
Bangladesh, Dhaka-1000, Bangladesh1;
Department of Microbiology and Immunology, University of
Texas Medical Branch at Galveston, Galveston, Texas
77555-10702; Microbiology and Tumor
Biology Centre, Karolinska Institute, S-171 77 Stockholm,
Sweden3; and Department of International
Health, Johns Hopkins University School of Hygiene and Public
Health, Baltimore, Maryland4
Received 12 June 2000/Returned for modification 6 July
2000/Accepted 1 August 2000
Aeromonads are causative agents of a number of human infections.
Even though aeromonads have been isolated from patients suffering from
diarrhea, their etiological role in gastroenteritis is unclear. In
spite of a number of virulence factors produced by
Aeromonas species, their association with diarrhea has not
been clearly linked. Recently, we have characterized a heat-labile
cytotonic enterotoxin (Alt), a heat-stable cytotonic enterotoxin (Ast), and a cytotoxic enterotoxin (Act) from a diarrheal isolate of Aeromonas hydrophila. Alt and Ast are novel enterotoxins
which are not related to cholera toxin; Act is aerolysin related and has hemolytic, cytotoxic, and enterotoxic activities. We studied the
distribution of the alt, ast, and
act enterotoxin genes in 115 of 125 aeromonads isolated
from 1,735 children with diarrhea, in all 27 aeromonads isolated from
830 control children (P = 7 × 10
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Prevalence of Enterotoxin Genes in Aeromonas spp.
Isolated From Children with Diarrhea, Healthy Controls, and the
Environment
4
for comparison of rates of isolation of aeromonads from cases versus
those from controls), and in 120 randomly selected aeromonads from
different components of surface water in Bangladesh.
Aeromonas isolates which were positive only for the
presence of the alt gene had similar distributions in the
three sources; the number of isolates positive only for the presence of
the ast gene was significantly higher for the environmental
samples than for samples from diarrheal children; and isolates positive
only for the presence of the act gene were not found in any
of the three sources. Importantly, the number of isolates positive for
both the alt and ast genes was significantly
higher for diarrheal children than for control children and the
environment. Thus, this is the first study to indicate that the
products of both the alt and ast genes may
synergistically act to induce severe diarrhea. In 26 patients,
Aeromonas spp. were isolated as the sole enteropathogen.
Analysis of clinical data from 11 of these patients suggested that
isolates positive for both the alt and ast
genes were associated with watery diarrhea but that isolates positive
only for the alt gene were associated with loose stools.
Most of the isolates from the three sources could be classified into
seven phenospecies and eight hybridization groups. For the first time,
Aeromonas eucrenophila was isolated from two children, one
with diarrhea and another without diarrhea.
*
Corresponding author. Present address: Department of
Microbiology, Faculty of Medicine, Kuwait University, P.O. Box 24923, Safat, 13110 Kuwait. Phone: (965) 533 2719. Fax: (965) 531 8454. Email:
john{at}hsc.kuniv.edu.kw.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»