A retrospective analysis of Salmonella isolation trends from pigs in Great Britain since 1994, with special reference to monophasic S. Typhimurium and antimicrobial resistance trends

The numbers of Salmonella reports from pigs in Great Britain have reduced considerably since the mid- 1990s, when up to 384 positive epidemiological group reports (incidents) per year were recorded, and numbers have been relatively stable since 2003 with less than 200 incidents reported per year. S. Typhimurium has been the most common serovar throughout the study period (between 58 and 75% of incidents). S. Derby, which was the second most common serovar for many years, has shown a downward trend since 2007, accounting only for 5% of incidents in 2009. At the same time, monophasic strains of S. Typhimurium have been on the rise since 2006. S. 4,5,12:i:- went from 0% in 2005 up to 6.2% of incidents in 2009, whereas S. 4,12:i:-, after showing a small peak in 1997, has also increased since 2007 and accounted for 1.2% of incidents in 2009