Improving the Timeliness of Salmonella Investigation


Impact Statement: 
Rapid response to new Salmonella cases is critical to decreasing the spread of disease and reducing the likelihood of an outbreak. The Santa Clara County Public Health Department in California used the Define, Measure, Analyze, Improve, Control (DMAIC)/Six Sigma approach to identify the root causes of “slow down” in the response time for Salmonella cases, cutting the time to investigation in half.

Beginning in January 2015, the Santa Clara County Public Health Department initiated an employee development program in Six Sigma. Four project teams implemented DMAIC/Six Sigma methodology. They selected projects uniquely positioned to support the department's strategic vision, goals, and objectives. This project focused on the department's strategic priority of strengthening prevention and response to current and emerging infectious diseases. The Communicable Disease Prevention & Control program in the department wanted to decrease its time to investigation for Salmonella cases, an established program performance measure. 

From September 2014 to March 2015, the program’s process for Salmonella case investigation was not as controlled as it needed to be to securely meet the performance measure of initiating the investigation within 48 hours of receipt by the program. The program saw some improvement to its process from January to March 2015 but decided to test three significant factors associated with barriers for timely Salmonella investigation based on its process from September 2014 to March 2015. Only one of the three factors was still a significant barrier from January to March 2015. The program’s process for Salmonella case investigation is now much more tightly controlled.

This Six Sigma project began shortly after another similar project, which was started out of the county’s Center for Leadership & Transformation (CLT), began in the Communicable Disease Prevention & Control program. The CLT project was pushing rapid change to transform county operations. The data from the Analyze phase of DMAIC supported the changes being driven by CLT project team members. Had the data not supported the interventions being tested, the Six Sigma and CLT members would have needed to decide about how to use the data to guide the changes within the program.

The following changes were implemented in April 2015: (1) the staffing assignment to the advice desk was shortened from weekly to daily, (2) notification of the clinician before initiating the phone call to the patient was discontinued, and (3) reports were distributed at time of receipt as opposed to the nurse manager batching the assignments. As a result, the average time to investigation for Salmonella cases decreased by 50%.

Organization that conducted the QI initiative: 
Santa Clara County Public Health Department

Webber, W. Public Health Quality Improvement Exchange. Improving the Timeliness of Salmonella Investigation. Mon, 10/12/2015 - 10:00. Available at Accessed April 14, 2024.

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cgizzi's picture
Submitted by cgizzi on

For those who are interested in learning more about the six sigma method, this is a nice example with clearly defined DMAIC steps.  Six sigma and lean/six sigma are both very appropriate methods to apply to public health QI efforts--more tools to be familiar with in our public health QI tool box.

Thanks for sharing your work, Whitney!

Cindan Gizzi, Tacoma-Pierce County Health Department and Public Health Centers for Excellence

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