Clinical Outcomes of Bacterial Co-Infections and Antibiotic Use in Adults Hospitalized with RSV vs Influenza

Overview

This multicenter cohort study of 986 adults hospitalized with RSV or influenza found bacterial co-infections in approximately one-quarter of patients across all virus groups. In patients with RSV, bacterial co-infection was not associated with increased mortality or adverse clinical outcomes, and early antibiotic treatment did not improve survival but was linked to longer hospital stays.

Background

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in hospitalized adults, with risks comparable to or exceeding those of influenza A or B. Bacterial co-infections have been reported in 8% to 29% of RSV cases, but their impact on outcomes remains unclear. Despite frequent antibiotic use in RSV patients, evidence supporting mortality benefit from antibiotics in the absence of bacterial co-infection is lacking. This study aimed to clarify the role of bacterial co-infections and antibiotic administration on clinical outcomes in adults hospitalized with RSV compared to influenza.

Data Highlights

Key Findings

• Bacterial co-infections were identified in 23% of RSV, 25% of influenza A, and 28% of influenza B hospitalized patients.
• Antibiotic use within 48 hours was common even among patients without bacterial co-infection: 77% in RSV, 71% in influenza A, and 75% in influenza B groups.
• In adjusted analyses, bacterial co-infection in RSV patients was not associated with increased mortality at 14, 30, or 90 days.
• Bacterial co-infection in RSV was also not linked to higher rates of high-flow oxygen therapy, mechanical ventilation, or longer length of hospital stay.
• Early antibiotic treatment in RSV patients was associated with prolonged length of stay but did not improve survival outcomes.

Clinical Implications

Clinicians should recognize that bacterial co-infections occur in about one-quarter of adults hospitalized with RSV or influenza, but in RSV patients, these co-infections do not appear to worsen mortality or other clinical outcomes. Routine early antibiotic administration in RSV without confirmed bacterial co-infection may not confer survival benefits and could contribute to longer hospital stays. Judicious use of antibiotics guided by microbiological testing is advisable to avoid unnecessary antibiotic exposure.

Conclusion

Bacterial co-infections are common in adults hospitalized with RSV and influenza, yet in RSV patients, they do not significantly impact mortality or critical care needs. Early antibiotic treatment does not improve survival in RSV and may prolong hospitalization, underscoring the need for targeted antibiotic stewardship in this population.

References

1. European Union RSV Hospitalization Estimates 2020 -- Respiratory Syncytial Virus Burden
2. Study Authors 2024 -- Clinical Outcomes of Bacterial Co-Infections and Antibiotic Administration in Adults Admitted for RSV Versus Influenza