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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 90, Num. 4, 1995, pp. 449
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Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol.
90(4): 449 Jul/Aug. 1995
Presence of Aeromonas trota in Aquatic
Environment
Valeria C Almeida*, Marly P Nunes
*Laboratorio de Zoonoses, Departamento de Microbiologia
Medica, Instituto de Microbiologia, CCS-UFRJ, Caixa Postal
68040, 21941-590 Rio de Janeiro, RJ, Brasil
Code Number: OC95088
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Text: 4K
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Key words: Aeromonas - estuary water - Aeromonas trota
In recent years, the interest in the Aeromonas genus has been
growing, due to its involvement in human infections, mainly
those of gastroenteric nature. It has been described 13
species for the genus, in which 11 have been isolated from
clinical material associated with infectious processes (JM
Janda 1991 Clin Microbiol Reviews 4: 397-410). Among these, we
detach Aeromonas trota which according to A Carnahan et
al. (1991 J Clin Microbiol 29: 1206-1210) seems to be an
agent of gastroenteritis in human beings and has been isolated
exclusively from human faecal material (Carnahan loc. cit.).
In this communication we report its isolation from a water
environment.
The strain of A. trota was isolated from a polluted estuary
which surrounds "Ilha do Fundao" in Rio de Janeiro. The
isolation was achieved after spreading the sediment obtained
by centrifugation of 500 ml of water (Sorvall RC2-B at 10.000
x g for 30 min) in plates with desoxicolate-citrate agar
(DCA-Merck) and, after the enrichment (24 hr - 37 C), in
alkaline peptone water (APW - pH 8.4). Plates were read after
incubation for 48 hr at 37 C. Lactose negative colonies were
submitted to tests for presumptive identification of the genus
(SL Abbott et al. 1992 J Clin Microbiol 30:
1262-66).
Oxidase positive strains, fermentative and resistant to the
vibriostatic agent (2,4-diamino-6,7 diisopropilpteridine
phosphate-SIGMA) 0/129 in a concentration of 150 ug/ml were
classified on the level of the species by the simplified
biochemical scheme proposed by Abbott (loc. cit.). Among these
strains, one presented biochemical characteristics which
coincided with those of Aeromonas trota (Table).
Some of the factors associated with the virulence of Aeromonas
genus, as described by Janda (loc. cit.), have been researched
and the strain was shown to be hemolytic in trypticase soy
agar (TSA-DIFCO) with 5% of rabbit blood and with hemolytic
activity of 1:8 through the methodology described by N
Cumberbatch et al. (1979 Infect Immun 23: 829-837).
Enterotoxigenic activity investigated according to the
technique of WA Dean et al. (1972 J Infect Dis 125:
407), and autoagglutination as described by JM Janda et
al. (1987 Infect Immun 55: 3070-77) were both negative.
The enzymatic profile was performed according to JM Janda and
EJ Bottone (1981 J Clin Microbiol 14: 55-60), and shown
negative regarding the production of lecitinase and elastase.
Protease and DNase activity were present in the strain.
Genus Aeromonas is widely distributed in aquatic environments
but, there are not reports of the isolation of the species A.
trota in environment (Carnahan loc. cit.). This seems to be
the first isolation and, considering the role of this bacteria
as a possible agent of gastroenteritis, it is of great
importance in the attempt to elucidate its epidemiologic
cycle, since water may be an important vehicle in its
transmission to man.
TABLE
Biochemical reactions of the Aeromonas trota strain
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Test Reaction for A. trota
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Esulin hydrolysis -
Vogues-Proskauer -
Fermentation of:
Arabinose -
Mannitol +
Sucrose -
Descarboxylase
Lysine +
Arginine +
Ornitine -
Susceptibility to:
Ampicillin S
Carbenicillin S
Cephalothin R
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-:negative;+:positive;S:sensitive;R:resistant
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Copyright 1995 Fundacao Oswaldo Cruz
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