Atypical Testing in the Viral Era - Report - MDSpire

Atypical Testing in the Viral Era

Study questions routine testing for atypical bacterial co-infection in viral respiratory hospitalizations

  • By

  • Conexiant News Staff

  • February 2, 2026

  • 3 min

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Clinical Report: Atypical Testing in the Viral Era

Overview

A large retrospective cohort study from Denmark indicates that routine testing for atypical bacterial co-infections in patients hospitalized with viral respiratory infections (specifically COVID-19, influenza A/B, or RSV) offers limited value.

Background

Understanding the prevalence of atypical bacterial co-infections in patients with viral respiratory infections is crucial for optimizing treatment strategies. Misguided empirical treatment can lead to unnecessary antibiotic use, contributing to resistance and adverse effects. This study provides insights into the appropriateness of routine testing and treatment in this patient population.

Data Highlights

ParameterValue
Total patients evaluated19,651
Patients tested for atypical bacteria2,369 (12%)
Positive tests for L. pneumophila7
Positive tests for M. pneumoniae14
Patients receiving empirical clarithromycin859 (4%)

Key Findings

  • Confirmed co-infection with atypical bacteria was rare, occurring in about 1% of tested patients.
  • Among 2,369 patients tested, 21 had positive results for atypical bacteria.
  • Most patients with confirmed co-infection did not receive early macrolide therapy.
  • Testing frequency varied by hospital and was associated with year, age, and disease severity.
  • Routine testing and empirical treatment for atypical pneumonia are not supported by current guidelines.

Clinical Implications

Clinicians should reconsider the routine use of atypical bacterial testing and empirical macrolide therapy in patients hospitalized with viral respiratory infections, except in cases of severe illness or atypical exposure.

Conclusion

The findings from this study challenge the necessity of routine atypical testing and treatment in viral respiratory infections, emphasizing a more judicious approach to antibiotic use in hospitalized patients, particularly for those with severe illness.

References

  1. Bo Langhoff Hønge, European Journal of Clinical Microbiology & Infectious Diseases, 2024 -- Atypical Testing in the Viral Era
  2. The Journal of Infectious Diseases — Advancements in Influenza Diagnostics for Home and Point-of-Care Settings: Implications for Treatment and Public Health Initiatives
  3. Acta Neuropathologica — Whole-Viral Genome Sequencing Targeting from Neuropathology Samples Preserved in Formalin-Fixed Paraffin
  4. American Journal of Epidemiology — Considerations on the Use of Test-Negative Design for Analyzing Mpox Risk Factors and Vaccine Efficacy
  5. Clinical management of COVID-19: living guideline, June 2025
  6. Azithromycin in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
  7. IDSA Guidelines on the Treatment and Management of Patients with COVID-19

Original Source(s)

Atypical Testing in the Viral Era

  • by Conexiant News Staff

  • February 2, 2026

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