Experimental infection with Mycoplama galliseptioum in chikens, turkeys, laying hens and chick embryos

Le pouvoir pathogène de la souche Mycoplasma gallisepticum R est exacerbé par 10 passages successifs sur poulets exempts d’organismes patho gènes spécifiés (EOPS). La souche réisolée MGR P10 est inoculée à des pou lets et des dindonneaux EOPS, des poules pondeuses conventionnelles et des embryons de poule de 19 jours d’incubation. Les symptômes et lésions observés chez ces hôtes révèlent le tropisme respiratoire et le fort pouvoir pathogène de la souche MGR P10. Un léger décrochement de la courbe de ponte est enregistré chez les poules pondeuses et une mortalité impor tante et rapide est observée après inoculation à l’embryon de 19 jours. Le pouvoir de diffusion de la souche est également mis en évidence.The Mycoplasma gallisepticum R strain is serially passaged ten times through specific pathogen free (SPF) chickens in order to exacerbate its potential pathogenicity. The recovered MGR P10 strain is inoculated in SPF chickens and turkeys, commercial laying fowl and nineteen-day-old chick embryos. The inoculation induces general and respiratory symptoms in the different hosts. Mortality occurs in the chicks hatched from inoculated embryos. A drop in egg production is observed in the laying hens. The strain is also shown to be able to spread from bird to bird

Effect of genetic resistance of the hen to Salmonella carrier-state on incidence of bacterial contamination: synergy with vaccination

Salmonella is one of the major sources of toxi-infections in humans. The association between egg consumption and Salmonella outbreaks is a serious economic and public health problem. To control the incidence of Salmonella in poultry flocks, many prophylactic means have been developed but none allows a total reduction of the risk. In a previous study, we derived mathematical models for Salmonella transmission and used them to appreciate the most important factors of variation of egg contamination rate and thus of risk of human contamination. Thanks to recent data of a selection experiment for increased or decreased rate of carrier-state ( also called divergent selection), we showed that mixing, in an equal proportion, animals issued from a line selected for a lower ( denoted Sal-) or higher propensity to carry Salmonella ( denoted Sal+) results in a reduction by half of the maximal percentage of contaminated animals but does not accelerate the extinction of the disease. Vaccination and selection should be synergic, since a former contamination reduces the maximal prevalence by 45 and 71%, respectively, in Sal+ or Sal- flocks respectively. These results show the interest in the introduction, even at a rather moderate percentage, of animals selected for a reduced rate of Salmonella carrier-state within commercial flocks. This could be achieved by using one or more selected lines in commercial crosses. These results must be confirmed experimentally while the mathematical model could be extended with minor modifications to other animal species or pathogenic species

Etude des possibilités de réduction, par voie génétique, du risque de portage de salmonelles

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Etude des possibilités de réduction, par voie génétique, du risque de portage de salmonelles

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Detection of Listeria monocytogenes in raw and pasteurized liquid whole eggs and characterization by PFGE.

International audienceListeria monocytogenes has been recognized as a human pathogen for decades and is known to be an important foodborne pathogen. There have been no documented foodborne L. monocytogenes illnesses due to the consumption of eggs or egg products, even though the bacterium has been isolated from faeces, body fluid, and oviducts of asymptomatic laying hens. In order to describe L. monocytogenes contamination of egg products, 144 liquid whole egg samples were collected from 3 different egg-breaking plants during 3 sampling periods. L. monocytogenes detection was performed on raw samples stored at 2 degrees C for two days (D+2) and on pasteurized samples stored at 2 degrees C at D+2 and at shelf-life date (SLD). L. monocytogenes was detected in 25 of the 144 raw egg samples collected, in 4 of the 144 pasteurized egg samples at D+2 and in 2 of the 144 ones analysed at SLD. Contamination of raw egg products appeared to be season dependant and was higher during summer and winter than during autumn. One hundred and ninety-six L. monocytogenes isolates were collected and serotyped; 3 serovars were demonstrated. The dominant serovar was L. monocytogenes 1/2a which was presented by 94.4% of the isolates. Typing of 196 L. monocytogenes isolates was carried out by macrorestriction of the genomic DNA with ApaI and AscI enzymes followed by pulsed field gel electrophoresis (PFGE). A large diversity was observed with 21 genotypes of L. monocytogenes, even for a given manufacturer. Nevertheless, most of the egg product samples were contaminated by one genotype, except for five samples which were contaminated by two or three distinct genotypes. The genotypes seem to be specific to each manufacturer. No cluster of L. monocytogenes was found to recur in the different plants over successive seasons

Reproduction expérimentale de mycoplasmose à Mycoplasma gallisepticum chez le poulet, le dindonneau, la poule pondeuse et l’embryon de poule

Experimental infection with Mycoplasma gallisepticum in chickens, turkeys, laying hens and cluck embryos. The Mycoplasma gallisepticum R strain is serially passaged ten times through specific pathogen free (SPF) chickens in order to exacerbate its potential pathogenicity. The recovered MGR P10 strain is inoculated in SPF chickens and turkeys, commercial laying fowl and nineteen-day-old chick embryos. The inoculation induces general and respiratory symptoms in the different hosts. Mortality occurs in the chicks hatched from inoculated embryos. A drop in egg production is observed in the laying hens. The strain is also shown to be able to spread from bird to bird.Le pouvoir pathogène de la souche Mycoplasma gallisepticum R est exacerbé par 10 passages successifs sur poulets exempts d’organismes pathogènes spécifiés (EOPS). La souche réisolée MGR P10 est inoculée à des poulets et des dindonneaux EOPS, des poules pondeuses conventionnelles et des embryons de poule de 19 jours d’incubation. Les symptômes et lésions observés chez ces hôtes révèlent le tropisme respiratoire et le fort pouvoir pathogène de la souche MGR P 10. Un léger décrochement de la courbe de ponte est enregistré chez les poules pondeuses et une mortalité importante et rapide est observée après inoculation à l’embryon de 19 jours. Le pouvoir de diffusion de la souche est également mis en évidence.Kempf Isabelle, Ollivier Claudine, Protais Jocelyne, Guittet Michèle, Cacou P.M., L'Hospitalier Rollande, Bennejean Georges, Morin Yannick, Quintin E., Lecocq L. Reproduction expérimentale de mycoplasmose à Mycoplasma gallisepticum chez le poulet, le dindonneau, la poule pondeuse et l’embryon de poule. In: Bulletin de l'Académie Vétérinaire de France tome 142 n°1, 1989. pp. 51-62

Comparison of resistance of different poultry lines to intramuscular or oral inoculation by Salmonella enteritidis

International audienc