Targeted antimicrobial stewardship intervention for inpatients with viral respiratory tract infections

Background: Patients admitted with respiratory tract infections receive empiric coverage for community acquired pneumonia (CAP), despite an underlying viral etiology in many cases. Rapid and sensitive molecular testing for respiratory viruses is increasingly utilized but the impact of rapid diagnostics to optimize management remains unclear.

Methods: Patients admitted to 2 acute care hospitals in Vancouver, Canada with a positive respiratory virus PCR between December 1, 2015 – April 30, 2016 were reported to the antimicrobial stewardship program (ASP) for direct audit and feedback interventions. Patients were excluded if they had other positive bacterial cultures or new lobar consolidation/pneumonia reported on chest imaging. We assessed the total duration of antimicrobial therapy after a viral diagnosis and relevant patient outcomes (ICU admission and/or mechanical ventilation, re-prescription of antimicrobials within 14 days of diagnosis; and re-admission, mortality and C. difficile within 30 days). Student’s t-test and Fisher’s exact test were utilized for analysis.

Results: Overall 133 patients had a positive respiratory virus result, and 41 (31%) were excluded based on positive microbiologic or radiologic criteria. Of the 92 eligible patients, 24 patients (26%) were not receiving antimicrobials and results for remaining patients (68) included influenza A (32%), influenza B (26%), human metapneumovirus (18%), respiratory syncytial virus (12%), parainfluenza 1/2/3 (7%), dual infection (3%) and adenovirus (1%). Recommendations were accepted in 51 patients (75%): 34 (67%) discontinued antimicrobials, 15 (29%) were stepped down from intravenous to oral therapy, and 2 (4%) continued current therapy. Seventeen interventions (25%) were rejected. Total duration of antimicrobial therapy after viral diagnosis was 2.0 days (95% CI: 1.2 – 2.8) for accepted recommendations compared to 5.6 days (95% CI: 4.4 – 6.8) for rejected recommendations, p<0.0001. There were no significant differences in other patient outcomes.

Conclusion: For hospitalized patients with suspected CAP, integrating rapid molecular testing for respiratory viruses with an ASP intervention was safe and contributed to reduced antibiotic utilization.