Experience with the rapid Directigen test for influenza

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Geriatric Medicine

Background:

• Rapid influenza diagnostic tests are crucial for timely clinical decisions in long-term care facilities.
• On-site testing reduces diagnostic delays compared to traditional laboratory methods.

Purpose of the Study:

• To evaluate the sensitivity and positive predictive value of the Becton-Dickson Directigen AB rapid antigen test.
• Comparison of rapid antigen test results against viral culture for influenza A detection.

Main Methods:

• Nasopharyngeal specimens collected from nursing home residents over three influenza seasons.
• Rapid antigen testing performed on-site; specimens transported for confirmatory viral culture.
• Analysis of 327 samples to determine test performance metrics.

Main Results:

• The Directigen AB test demonstrated a positive predictive value of 94% for influenza A.
• Sensitivity of the rapid test was found to be 64% compared to viral culture.
• Early influenza prophylaxis was often initiated based on positive rapid test results.

Conclusions:

• The Directigen AB test is a reliable indicator of influenza A when community viral activity is confirmed.
• Despite limited sensitivity, the rapid test facilitates early laboratory confirmation and timely prophylaxis.
• On-site rapid influenza testing aids in prompt management within nursing home settings.