The Impact of Rapid Molecular Diagnostics for Influenza on Antibiotic Stewardship in the Emergency Department-An Observational Retrospective Study

The clinical diagnosis of respiratory tract infections (RTIs) may result in unnecessary antibiotic treatment due to clinical exams' low sensitivity and specificity to differentiate viral from bacterial infections and costly diagnostic work-ups. Unnecessary antibiotic consumption drives antibiotic resistance. We explored whether a rapid influenza-specific polymerase chain reaction (PCR) assay reduced antibiotic use in an emergency room before the COVID-19 pandemic.

We conducted an observational retrospective study of patients with RTI symptoms treated in the ER of the University Hospital Basel from September 2014 to June 2015. We evaluated the impact of rapid diagnostic results, such as an influenza-specific PCR, blood sample results, and radiological imaging, on antibiotic prescription rates. Patient-related confounding factors were included since a patient's clinical condition affects doctors' clinical decision-making.

We included 607 patients with RTIs, tested with PCR for influenza A or B. Logistic regression showed that the odds ratio (OR) of being treated with antibiotics was significantly reduced by more than two-thirds in patients with a positive influenza PCR result (OR = 0.37; 95% CI, 0.22-0.59; p < 0.001). Increasing C-reactive protein (CRP) levels by tenfold (OR = 5.14; 95% CI, 3.34-8.12; p < 0.001) or suspected chest infection on a radiograph (OR = 5.81; 95% CI, 3.23-10.89; p < 0.001) increased the OR of antibiotic treatment by fivefold. The highest OR for antibiotic prescription was due to increased procalcitonin level by tenfold (OR = 10.13; 95% CI, 4.79-23.4; p < 0.001).

Our study provides real-world evidence from a pre-COVID-19 ER setting of diagnostic tools used for RTI evaluation and their impact on antibiotic prescriptions. Rapid influenza-specific PCR results may affect the prescription rate of antibiotics but should be seen as part of a comprehensive diagnostic approach to guide clinical decision-making.