Survey of the prevalence of Salmonella species on commercial laying farms in the United Kingdom

A survey of salmonella infection on 454 commercial layer flock holdings in the UK was carried out between October 2004 and September 2005. Fifty-four (11-7 per cent, 95 per cent confidence interval 9-3 to 14-0 per cent) were salmonella positive. The most common serovar identified was Salmonella Enteritidis at a prevalence of 5-8 per cent, and 70 per cent of these isolates were phage types 4, 6, 7 and 35. Salmonella Typhimurium was the second most prevalent serovar, found in 1-8 per cent of the farms. Of the three other serovars given top priority by the EU because of their public health significance, Salmonella Virchow and Salmonella Infantis were each isolated from one holding, but Salmonella Hadar was not isolated from any of the holdings. Analysis of antimicrobial resistance patterns revealed that over 76 per cent of the isolates were sensitive to all of the 16 drugs tested, and all the isolates were sensitive to ciprofloxacin, gentamicin, ceftazidime, apramycin, amikacin, amoxicillin/clavulanic acid, neomycin and cefotaxime.