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Considerations for assessing Salmonella, E. coli and Shigella clusters for further follow-up

New or updated multi-jurisdictional¹ Salmonella, E.coli or Shigella cluster considered genetically related by WGS²

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Assessment and Review

Prioritization based on the following considerations, as relevant:

• • • • • • • • • • • • • Serotype frequency
                        • Number of cases in the cluster
                        • Allele range and branching
                        • Demographic profiles
                        • Isolation date ranges (or available dates)
                        • Presence of a nonclinical isolate in the cluster 
                        • NML’s prioritization level
                        • Historical context (what we have previously learned about the cluster)
                        • How the isolates in the cluster relate to each other & all other isolates in PNC database
                        • Other unique or potentially interesting features

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Potential follow-up with P/Ts for available exposure information, taking into account purpose of follow-up and number of requests to P/Ts

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Further investigation, if warranted based on review of available information

Note: these are intended to be guidelines; if additional information on clusters is available and suggests that further follow-up on clusters not meeting these criteria is warranted, CFEZID may initiate follow-up.

¹ Clusters are considered multi-jurisdictional when they contain human isolates from 2 or more P/Ts

² Guidelines for WGS interpretation are determined by the Public Health Agency of Canada’s National Microbiology Laboratory