Survival of Escherichia coli in the intestine of fish

Abstract

Establishment and persistence of Escherichia coli in the intestine of rainbow trout. Oncorhynchus mykiss (Walbaum), was investigated. Infection was achieved by ingestion of contaminated feed but not by bath exposure. At 1 5°C, E. coli was found to increase in number in the intestine offish after an initial decline, and could still be detected after 4 days. At 6°C it was detected for 2 days but the numbers declined steadily. A similar trend was observed when extracted gut content was inoculated with E. coli in vitro: after an initial decline, bacterial growth recovered. Gut content in vitro also was a suitable environment for plasmid-mediated transfer of resistance.Oxytetracycline resistance was transferred successfully from Aeromonas saUnonicida to E. coli. This could not be reproduced in vivo, perhaps because the inoculum of A. sahnonicida achieved per fish was not high enough as it did not withstand drying well on the feed pellets. Introduction by gavage was also tried but failed to establish an A. salmonicida infection. These results show that at temperatures around 15°C, the presence of E. coli in fish need not be an indicator of recent passage through polluted waters. It may be a consequence of infection established many days before, and perhaps some distance away. Furthermore, although transfer of antibiotic resistance from a fish pathogen did take place in the environment of fish intestinal content, the likelihood of this being a high-risk route for acquisition of resistance by bacteria that can affect humans is low.

The decoupling between genetic structure and metabolic phenotypes in Escherichia coli leads to continuous phenotypic diversity

“…, 1990). Other studies showed that E. coli can establish and persist for a few days in fish intestines, giving them the opportunity to spread to distant waters (Rio‐Rodriguez et al. , 1997; Guzmán et al.…”

“…For instance, in a farm environment, from the inoculation of a cow, a strain can be recovered from caretakers, mice, pigs, fowls and flies in a few days ( Marshall et al , 1990 ). Other studies showed that E. coli can establish and persist for a few days in fish intestines, giving them the opportunity to spread to distant waters ( Rio-Rodriguez et al , 1997 ; Guzmán et al , 2004 ). Therefore, the continuous variations in metabolic phenotypes can also reflect the adaptation to past niches.…”

Growth, body composition, intestinal enzyme activities and microflora of juvenile Jian carp (Cyprinus carpiovar. Jian) fed graded levels of dietary valine

“…salmonicida in Atlantic salmon (Salmo salar L.) in vitro. Additionally, E. coli in the intestine are pathogens with the particular potential of causing enteric infection (Rio-Rodriguez et al 1997). These intestinal microflora are sensitive to dietary changes (Ringø & Birkbeck 1999).…”

Vacunas de ADN para peces de vivero

“…Although the chances are most probably minimal, other bacteria can theoretically take up the vaccine plasmid. However, E. coli, the most likely organism that could be implicated in transmitting the plasmid outside the target species, is not considered a natural component of the gut flora of salmonids under culture conditions (14) and is absent from the intestinal content of cultured fishes (25). In order to achieve the highest possible level of precaution, DNA vaccine plasmids for fish should be limited to include only the strictly necessary genes and regulatory elements, and be devoid of gene elements such as genes that mediate resistance to important antibiotics.…”