Characterisation of the invasiveness of monophasic and aphasic Salmonella Typhimurium strains in day-old and point-of-lay chickens.

In this study, seven groups of day-old and point-of-lay commercial Hy-line chicken layers were separately challenged with 4 different strains of monophasic ST, one aphasic ST, one biphasic ST and one egg invasive SE strain. Tissue samples and cloacal swabs (point-of-lay chickens only) were collected at regular intervals post-challenge in order to recover the Salmonella challenge strains. In day-old chicks, only the aphasic ST strain and the SE strain were recovered after direct plating, suggesting that the number of salmonellas colonising the tissues of the chicks infected with the other strains was likely to be low. Interestingly, all the strains colonised well in the point-of-lay chickens, and there was no statistical difference in the overall number of positive samples or Salmonella counts between the seven strains. Salmonella was recovered from the point-of-lay birds upto the end of the study (20 days after challenge). Monophasic and aphasic ST strains colonised point-of-lay birds as efficiently as biphasic ST and SE strains. Further studies are necessary to estimate the invasiveness of these strains in naturally-infected vaccinated laying hens, and to assess the impact of natural infection on egg contamination.
PMID: 24802091 [PubMed - as supplied by publisher]

Source: Avian Pathology - May 7, 2014 Category: Pathology Authors: Martelli F, Gosling R, Kennedy E, Rabie A, Reeves H, Clifton-Hadley F, Davies R, La Ragione R Tags: Avian Pathol Source Type: research