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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 91, Num. 5, 1996, pp. 619-620
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Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 91(5), 619-620,
Sep/Oct 1996,
RESEARCH NOTE
Enterotoxigenic Capacity of Campylobacter coli
Strains Isolated from Humans and Bovines
A Tresierra-Ayala/^+, H Fernandez*, J Zamora**
Departamento de Microbiologia, Universidad Nacional de la
Amazonia Peruana, Casilla Postal 751, Iquitos, Peru
*Instituto de Microbiologia Clinica, Facultad de Medicina
**Instituto de Microbiologia, Facultad de Ciencias,
Universidad Austral de Chile, Casilla Postal 567, Valdiva,
Chile
^+Corresponding author. Fax: 51-94-23.4723
Received 5 February 1996
Accepted 29 March 1996
Code Number: OC96111
Size of Files:
Text: 6.7K
Graphics: No associated graphics files
[TABLES AND FIGURES AT END OF TEXT]
Key words: Campylobacter coli - ileal loop test
- enterotoxigenic capacity - pathogenicity - reservoirs
In developing countries, Campylobacter coli and C.
jejuni are important agents associated with diarrheic
syndrome. In Latin America, their isolation rates vary from
0.6% in Cuba to 23.0% in Iquitos, in the Peruvian jungle
region (H Fernandez 1992 J Braz Ass Develop Sci 44: 39-
43). However, most of the studies have been done only with
C. jejuni, in spite of that C. coli has similar
importance (T Daikoku et al. 1989 FEMS Microbiol Lett
58: 33-36).
Enterotoxigenic capacity has been identified as a pathogenic
mechanism in Campylobacter (G Ruiz-Palacios et al. 1983
Lancet 2: 250-251, H Fernandez & L Trabulsi 1995
Biol Res 28: 205-210). Some researchers have reported
that this property is similar in both species (W Johnson & H
Lior 1986 J Clin Microbiol 24: 275-281), however others
have determined that the enterotoxigenic capacity of C.
coli is lower than C. jejuni or this bacterium has
not enterotoxic property (T Daikoku et al. 1989 FEMS
Microbiol Lett 58: 33-36, C Fricker & R Park 1989 J
Appl Bacteriol 66: 477-490).
The aim of this study was to evaluate the presence of
enterotoxigenic capacity in 15 strains of C. coli
isolated from humans (7 strains) and from bovines (8 strains),
previously maintained under freezing temperature (-35C).
Using the Lior biotyping scheme (H Lior 1984 J Clin
Microbiol 20: 636-640), 3 belonged to biovar I and 12 to
biovar II (Table).
The enterotoxigenic capacity was determined by the ligated
ileal loop test in rats (S Saha et al. 1988 J Med Microbiol
26: 87-91). A cell-free supernatant of each strain was
prepared from a 72 hr culture in Brucella broth
incubated at 37C in microaerophilic conditions and 500 ml were
innoculated individually into single 5-cm-long ligated ileal
loops of adult Holtzman rats (170 to 250 g). Sterile Brucella
broth and the cell-free supernatant of a known enterotoxigenic
C. coli strain were used as negative and positive
control, respectively. After 18 hr, the animals were killed
by ether overdose and the ileum was examined. Distention of
the loops with fluid accumulation was considered as a positive
result (98 ml/cm of intestine or more, as determined by
Students t test). The volume/length ratio in negative control
was consistently <20 ml/cm. The tests were done in two rats
simultaneously.
The enterotoxigenic capacity was determined in 66.7% of the
strains, belonging two strains to the biovar I and eight to
the biovar II. Some investigators have reported rates higher
than our values. H Bok et al. (1991 J Clin Microbiol
29: 1262-1264) and W Johnson and H Lior (1986 J Clin
Microbiol 24: 275-281) determined rates of 100% and 83.2%,
respectively.
Moreover, our results showed that 57.1% of the culture
supernatants of human strains and 75% of the supernatants of
bovine strains produced fluid accumulation. They are in
agreement with the results reported in England by C Fricker
and R Park (1989 J Appl Bacteriol 66: 477-490) because
in both studies, the difference between the human and bovine
strains, in relation to their enterotoxigenic capacity, was
not significant (p>0.05). Consequently, this characteristic
was not associated with the biovar neither with the strains
source.
The presence of enterotoxigenic strains in bovines increases
the evidences that these animals could be an important
infection source for humans. Some authors have expressed that
in developing countries, the close association between man and
animals may lead to a cycle of infection that would increase
the toxigenicity of Campylobacter strains by
consecutive passages through the intestinal tract (S Saha et
al. 1988 J Med Microbiol 26: 87-91). A similar
enhancement of other pathogenic factors of Campylobacter
has been suggested by D Newell et al. (1985 J Hyg
94: 45-54).
The present study suggests that the enterotoxigenicity could
be an important pathogenic mechanism by which C. coli
may produce disease. For this reason we consider that this
bacterium must have the same importance as C. jejuni in
relation to their enterotoxigenicity.
This work received financial support from Grants Fondecyt 59-
89; Fondecyt 217-90 and General Office of Investigation -
UNAP.
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TABLE Distribution of biovars of Campylobacter coli
strains studied according to the isolation source and
determination of their enterotoxigenic capacity
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Biovars
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Source I II Total
TOX/TOT TOX/TOT TOX/TOT
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Human 1/2 3/4 4/7 (57.1)
Bovine 1/1 5/7 6/8 (75.0)
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Total 2/3 (66.7) 8/12 (66.7) 10/15 (66.7)
TOX/TOT: no. of enterotoxigenic strains/no. of strains
studied; ( ): % of strains with enterotoxigenic capacity.
The difference between the enterotoxigenic capacity of human
and bovine strains was not significant (p>0.05).
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Copyright 1996 Fundacao Oswaldo Cruz
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