Human Salmonella Isolates, 2013 No. 12, December

The number of isolates this month (n=77) showed a slight increase in comparison to the number of isolates received in December 2012 (n=69). Salmonella Typhimurium phage type 56 variant (5.8% in December 2012 and 16.9% in December 2013) was the predominant serotype. Salmonella Typhimurium phage type 126a was confirmed for the first time in New Zealand.

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.

Salmonella Montevideo (typing results)

• Isolates from 5/6 cases have been typed by Pulsed Field Gel Electrophoresis and all share an indistinguishable PFGE profile. This profile is distinguishable 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.
• From Jan to November 2013 (prior to this cluster) 4 cases of S. Montevideo were confirmed. 2/4 reported overseas travel within the incubation period. As at 17 December no further cases have been identified.