Human Salmonella Isolates, 2013 No. 11, November

The number of isolates this month (n=100) showed a slight decrease in comparison to the number of isolates received in November 2012 (n=104). Salmonella Typhimurium phage type 56 variant (10.6% in November 2012 and 10% in November 2013) was the predominant serotype. Uncommon serotypes confirmed this month included Salmonella Enteritidis phage type 9c (2 human isolates since 2002) and S. Waycross (4 human isolates since 2002).

The S. Typhimurium phage type 56 variant was known as S. Typhimurium phage type RDNC-May06 prior to July 2013. Further characterisation work undertaken by the Salmonella Reference Unit at Colindale (Public Health England) identified this phage type as 56 variant.

A cluster of 5 cases of Salmonella Montevideo was confirmed in the Bay of Plenty region this month. PFGE has been performed and all cases share the same PFGE profile. The profile is distinguishable to the PFGE profile from samples of imported tahini implicated in a similar outbreak in 2012. Local environmental investigations at the food premises have not identified any food control failures or sick food handlers that could account for the source of these infections. Investigations are on-going.