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Resistance gene transfer during treatments for experimental avian colibacillosis.

ABSTRACT: An experiment was conducted in animal facilities to compare the impacts of four avian colibacillosis treatments-oxytetracycline (OTC), trimethoprim-sulfadimethoxine (SXT), amoxicillin (AMX), or enrofloxacin (ENR)-on the susceptibility of Escherichia coli in broiler intestinal tracts. Birds were first orally inoculated with rifampin-resistant E. coli strains bearing plasmid genes conferring resistance to fluoroquinolones (qnr), cephalosporins (bla(CTX-M) or bla(FOX)), trimethoprim-sulfonamides, aminoglycosides, or tetracyclines. Feces samples were collected before, during, and after antimicrobial treatments. The susceptibilities of E. coli strains were studied, and resistance gene transfer was analyzed. An increase in the tetracycline-resistant E. coli population was observed only in OTC-treated birds, whereas multiresistant E. coli was detected in the dominant E. coli populations of SXT-, AMX-, or ENR-treated birds. Most multiresistant E. coli strains were susceptible to rifampin and exhibited various pulsed-field gel electrophoresis profiles, suggesting the transfer of one of the multiresistance plasmids from the inoculated strains to other E. coli strains in the intestinal tract. In conclusion, this study clearly illustrates how, in E. coli, "old" antimicrobials may coselect antimicrobial resistance to recent and critical molecules.

SUBMITTER: Dheilly A

PROVIDER: S-EPMC3256041 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Resistance gene transfer during treatments for experimental avian colibacillosis.

Dheilly Alexandra A Le Devendec Laëtitia L Mourand Gwenaëlle G Bouder Axelle A Jouy Eric E Kempf Isabelle I

Antimicrobial agents and chemotherapy 20111010 1

An experiment was conducted in animal facilities to compare the impacts of four avian colibacillosis treatments-oxytetracycline (OTC), trimethoprim-sulfadimethoxine (SXT), amoxicillin (AMX), or enrofloxacin (ENR)-on the susceptibility of Escherichia coli in broiler intestinal tracts. Birds were first orally inoculated with rifampin-resistant E. coli strains bearing plasmid genes conferring resistance to fluoroquinolones (qnr), cephalosporins (bla(CTX-M) or bla(FOX)), trimethoprim-sulfonamides, a ...[more]

PMID: 21986830

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Project description:Intestinal infection with enterotoxigenic Escherichia coli (ETEC) is an important disease in swine resulting in significant economic losses. Knowledge about the epidemiology, the diagnostic approach and methods of control are of fundamental importance to tackle the disease. The ETEC causing neonatal colibacillosis mostly carry the fimbriae F4 (k88), F5 (k99), F6 (987P) or F41, while the ETEC of post-weaning diarrhoea carry the fimbriae F4 (k88) and F18. These fimbriae adhere to specific receptors on porcine intestinal brush border epithelial cells (enterocytes), starting the process of enteric infection. After this colonization, the bacteria produce one or more enterotoxins inducing diarrhoea, such as the heat stable toxin a (STa), the heat stable toxin b (STb), and the heat labile toxin (LT). A role in the pathogenesis of the disease was demonstrated for these toxins. The diagnosis of enteric colibacillosis is based on the isolation and quantification of the pathogenic E.coli coupled with the demonstration by PCR of the genes encoding for virulence factors (fimbriae and toxins). The diagnostic approach to enteric colibacillosis must consider the differential diagnosis and the potential different causes that can be involved in the outbreak. Among the different methods of control of colibacillosis, the use of antimicrobials is widely practiced and antibiotics are used in two main ways: as prophylactic or metaphylactic treatment to prevent disease and for therapeutic purposes to treat diseased pigs. An accurate diagnosis of enteric colibacillosis needs an appropriate sampling for the isolation and quantification of the ETEC responsible for the outbreak by using semi-quantitative bacteriology. Definitive diagnosis is based on the presence of characteristic lesions and results of bacteriology along with confirmation of appropriate virulence factors to identify the isolated E.coli. It is important to confirm the diagnosis and to perform antimicrobial sensitivity tests because antimicrobial sensitivity varies greatly among E. coli isolates. Growing concern on the increase of antimicrobial resistance force a more rational use of antibiotics and this can be achieved through a correct understanding of the issues related to antibiotic therapy and to the use of antibiotics by both practitioners and farmers.

Project description:Avian Colibacillosis is among the major causes of economic loss in the poultry industry worldwide, with a more vivid impact on developing countries. The involvement of several bacteria has made it challenging to develop effective vaccines for this disease, particularly because it is notoriously difficult to make a vaccine that contains all the contributing pathogenic bacteria. Here, we report the design and fabrication of a bacterial ghost (BG) of E. coli O78:K80, which is among the major bacterial serotypes responsible for this disease. The generated ghost is then exploited as a homologous vaccine against Avian Colibacillosis. We demonstrate that hole formation in the cell wall of E. coli O78:K80 can happen properly in optical densities as high as 0.8 compared to the 0.3-0.4 standard for bacteria like E. coli TOP10. This is especially advantageous for mass production of this ghost which is a vital factor in development of any BG-based vaccine. Compared to E. coli TOP10, we faced a great challenge in transforming the wild type bacteria with the E-lysis plasmid which was probably due to higher thickness of the cell wall in O78:K80. This, however, was addressed by treating the cell wall with a different combination of ions.The vaccine was administered to Ross 308 broiler chickens via injection as well as through their respiratory system at a dose of 1010 BGs, repeated 3 times at weekly intervals. Chickens were then challenged with the wild type O78:K80 at a dose of 1011 bacteria together with Infectious Bronchitis H120 vaccine (as immunosuppressant) one week after the last immunization. Air sac lesions were significantly reduced in BG vaccinated groups in comparison with the control group. The levels of IFNγ, IgA and IgY were measured in the serum of immunized chickens as an indication of immune response and were compared with those of the chickens vaccinated with killed bacteria. The results show that O78:K80 BG can be used as an efficient homologous vaccine against Colibacillosis disease in poultry. We expect our findings can serve as the starting point for designing more sophisticated vaccines that contain all three major pathogenic bacteria involved in avian Colibacillosis.

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Dataset Information

Resistance gene transfer during treatments for experimental avian colibacillosis.

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Resistance gene transfer during treatments for experimental avian colibacillosis.

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