Résumé:
The present study provides the first data about the prevalence of Salmonella contamination of
broilers and slaughterhouses in the region of Constantine, Algeria. The serotypes and antibiotic
resistance patterns of the isolates were determined, and risk factors contributing to the
contamination were evaluated.
A total number of 2490 samples, 1800 originating from 30 broiler farms and 690 from 15
slaughterhouses, were taken during 2 periods: October 2005-June 2006 and September 2006-
March 2007. Salmonella contamination concerned 37 % of the broiler farms and 73 % of the
slaughterhouses.
Among the 55 isolates recovered, ten different serotypes were identified. The most frequently
recovered serotypes in both slaughterhouses and breeder farms were S. Hadar (36.4%, n=20), S.
Virchow (16.4%, n=9), S. Infantis (10.9%, n=6), and S. Albany (10.9%, n=6). S. Carnac (7.3%,
n=4). Isolates belonging to S. Heidelberg (1.8%, n=1), and S. Rissen (1.8%, n=1) were found
only in farms, while those belonging to S. Typhimurium (9.1%, n=5), S. Enteritidis (3.6%, n=2),
and S. Montevideo (1.8%, n=1) were recovered only from slaughterhouses. Thirty nine isolates
(79.9 %) were resistant to at least one antibiotic and 50.9 % were multi-resistant, i.e. resistant to
two or more antibiotic molecules. Among the 55 isolates, 56.4% (n=31) were resistant to
streptomycin, 34.5% (n=19) to tetracyclines, 27.2 % (n=15) to nalidixic acid, 12.7% (n=7) to
ofloxacin and 1.8% (n=1) to enrofloxacin. Finally, 7 distinct antibiotic resistance profiles were
identified.
In parallel, four risk factors were found that were significantly associated with Salmonella
contamination. These risk factors highlight the hazards of the broiler channel, particularly linked
to poor technical and hygiene practices.
On the another side, the genotypic characterization of the stocks gave us 16 profiles per EricPCR, 20 profiles by is-PCR and 34 profiles by PFGE. The 3 methods, and particularly the PFGE,
showed the clonality of some sérotypes, confirming the diffusion and the persistence of the same
clone through the field, and in our area, but also the polymorphism of others sérotypes indicating
the diversity of the potential tanks in nontyphoidal salmonella.
The comparison of our PFGE profiles to those of the bank of data of the AFSSA, Maisons
Alfort, France, informs us about the diffusion, sometimes international, of some sérotypes,
facilitated by the increasing levels of trade, at the eve of the accession of Algeria to the World
Trade Organization.
