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Escherichia coli pathogenic for poultry: molecular approaches to improve diagnosis and control

Contract nr: FAIR-CT98-4093
Project nr: 4093
Project type: SC
Starting date: 01/01/1999
Duration: 36 months
Total cost: 1,024,114 EUR
EC Contribution: 874,833 EUR
Scientific Officer: Isabel MINGUEZ-TUDELA
Research topic: Animal health
Acronym: APEC

Background:
Among bacterial infections, colibacillosis is the prime cause of morbidity and mortality in poultry breeding, where it provokes different types of syndromes, mainly respiratory tract infections and reproductive disorders. Two unsolved problems actually impair a satisfactory control of avian colibacillosis in Europe:

1) there are currently no reliable methods to be used in veterinary diagnostic laboratories which would allow for the identification of the causative strains of Escherichia coli;
2) no fully effective vaccination is presently available for avian colibacillosis, probably due to the large variety of E. coli strains which are able to provoke colibacillosis infection in poultry.

Moreover, although several data and observations argue in favour of close genetic relationships between some pathogenic E. coli isolates of human and avian origin, especially those involved in extra-intestinal and septicaemic diseases, this particular point has never been well-documented in Europe. Finally, the intensive use of antibiotics in animal husbandry leads to the selection of antibiotic resistances, which may be transferred to Gram-negative bacteria pathogenic for man.

Objectives:
This study includes two main objectives:

1) to improve poultry breeding by improving the control of avian colibacillosis, which could result from a better knowledge of the responsible E. coli strains;
2) to monitor human health, through a detailed study of genetic homologies between avian and human pathogenic E. coli isolates, and a survey of bacterial resistance to antibiotics.

Description:
For this purpose, the work will be organised into three complementary parts.

1) The specific characteristics of avian pathogenic E. coli (APEC) will be investigated on a large sample of avian E. coli strains collected in three European countries (FR, ES, and BE). This characterisation will rely on classical bacteriological methods (biotyping, serotyping), detection of virulence genes and of pathogenicity islands (clusters of several different virulent genes, closely linked on a same genetic support) by PCR and genetic probes, and it will be completed using molecular epidemiology methods (pulsotyping and ribotyping).

2) The obtained data will be analysed according to the origin of strains, using statistical methods. The results of this analysis will allow us to define different pathotypes among APEC, whose characteristics will be used to set out new diagnostic methods and to select strains for vaccination, based on common virulence factors.

3) The evaluation of APEC as a potential threat to human health. This study will be supported by a detailed investigation of genetic relationships between avian and human pathogenic E. coli isolates. It will include the study of homologies in genetic background as well as in genetic organisation of virulence genes and pathogenicity islands, the detection of E. coli pathotypes potentially pathogenic for man (such as 0157:H7), which can be present in a low proportion among E. coli of avian origin. Part three will also include a survey of the frequency of resistance of APEC to therapeutic antibiotics, in relation to different avian species (poultry, turkeys and ducks), and to the use of antibiotics in the three countries participating to the project. Special emphasis will be placed on the more recent antibiotic molecules which are used both in human medicine and in animal husbandry, including a comparative study of the mechanisms of resistance to the quinolones in human and in avian E. coli strains.

This project will involve five partners from three countries (Belgium, France and Spain), among which are four research teams which have reached an expert position in studying E. coli pathogenic for poultry, for other animals, or for man, and an industrial firm. We will be able to constitute a reference and well-documented European collection of avian pathogenic E. coli (APEC) in order to improve diagnosis of avian colibacillosis through adapted diagnostic assays, and to make a contribution to the control of this disease. This study should also improve the sanitary status of poultry products, and also allow us to evaluate the potential risk for human health, which are two priorities of the work programme.

Current situation/results:
Two meetings have been held with all project participants in Tours, France (January 1999) and in Paris (December 1999). During the first year, 996 E. coli isolates were collected, of which 700 isolates were studied in the different laboratories. Strains were biotyped by P1, serotyped by P2, and virulence genes were searched for using molecular methods by P1, P3, P4 and P5. Antibio-resistance phenotypes were determined by P1. Furthermore, several genomic fragments specific for an APEC strain were isolated by genomic subtraction. Their frequency among APEC strains and their possible belonging to pathogenicity islands is presently investigated.


Coordinator
Maryvonne DHO-MOULIN
Institut National de la Recherche Agronomique
CR INRA Tours-Nouzilly Station de Pathologie Aviaire et de Parasitologie
F-37380 Nouzilly
Tel.: +33 2 47 42 77 63
Fax: +33 2 47 42 77 74
E-mail: dhomouli@tours.inra.fr


Partners

  • François BIET
    SANDERS-ALIMENTS
    Laboratoires vétérinaires
    Technopole
    BP 1419
    F-53014 Laval Cedex
    Tel: +33 2 43 59 76 10
    Fax: +33 2 43 56 20 87
    E-mail: francois.biet@libertysurf.fr

  • Eric OSWALD
    Institut National de la Recherche Agronomique
    ENVT
    Chemin de Borde-Rouge - Auzeville
    F-31326 Castanet Tolosan
    Tel.: +33 5 61 19 39 91
    Fax: +33 5 61 19 39 75
    E-mail: e.oswald@toulouse.inra.fr

  • Jacques MAINIL
    Université de Liège
    Place du XX Août 7
    B-4000 Liège
    Tel.:+32 4 366 40 50
    Fax: +32 4 366 41 22
    E-mail: jg.mainil@ulg.ac.be

  • Jorge BLANCO ALVAREZ
    Universidad de Santiago de Compostela
    Facultad de Veterinaria
    E-27 002 Lugo
    Tel.: +34 982 28 59 36
    Fax: +34 982 25 21 95
    E-mail: jba@lugo.usc.es

 
 
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