# Influenza A Co-infection With Atypical Bacteria: A Report of Two Cases

**Authors:** Subasima Sekar, Krithika Gopalakrishnan, Sribal Selvarajan, Shanthi Mariappan

PMC · DOI: 10.7759/cureus.103459 · Cureus · 2026-02-12

## TL;DR

This paper reports two cases where people infected with the influenza A virus also had co-infections with atypical bacteria, showing how early diagnosis and treatment can lead to better outcomes.

## Contribution

The novelty lies in documenting co-infections with Influenza A and atypical bacteria across age groups and emphasizing the benefits of multiplex molecular diagnostics.

## Key findings

- Two cases of Influenza A co-infected with Chlamydia pneumoniae and/or Mycoplasma pneumoniae were identified.
- Early targeted therapy based on multiplex PCR improved clinical outcomes in both patients.
- Co-infections with atypical bacteria can occur in both elderly and pediatric populations.

## Abstract

Influenza A virus infection is associated with a wide range of clinical manifestations, from mild upper respiratory infections that resolve on their own to severe pneumonia and sepsis. Bacterial co-infections, particularly due to atypical pathogens such as Chlamydia pneumoniae and Mycoplasma pneumoniae, may alter disease severity and clinical presentation, especially in paediatric patients and adults with underlying comorbidities. We describe two cases of Influenza A virus infection complicated by atypical bacterial co-infections. The first case involved an elderly female with multiple chronic comorbidities who presented with respiratory sepsis and was found to have co-infection with Influenza A virus and Chlamydia pneumoniae. The second patient was a two-year-old female with concomitant infection due to Influenza A virus, Chlamydia pneumoniae and Mycoplasma pneumoniae. Pathogen identification was achieved using multiplex real-time polymerase chain reaction. In both patients, early initiation of targeted antiviral and antibacterial therapy resulted in clinical improvement and favourable outcomes. Co-infection with the influenza A virus and atypical bacterial pathogens can occur across age groups. Early microbiological diagnosis using multiplex molecular assays supports timely, pathogen-directed therapy and may mitigate disease severity and complications, thereby ensuring the good health and well-being of the patients.

## Linked entities

- **Species:** Chlamydia pneumoniae (taxon 83558)

## Full-text entities

- **Diseases:** pneumonia (MESH:D011014), respiratory infections (MESH:D012141), infection (MESH:D007239), sepsis (MESH:D018805), Bacterial co-infections (MESH:D060085), respiratory sepsis (MESH:D012131), Influenza A virus infection (MESH:D007251)
- **Species:** Homo sapiens (human, species) [taxon 9606], Chlamydia pneumoniae (species) [taxon 83558], Mycoplasmoides pneumoniae (Filterable agent of primary atypical pneumonia, species) [taxon 2104], Influenza A virus (no rank) [taxon 11320]

## Full text

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## Figures

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## References

11 references — full list in the complete paper: https://tomesphere.com/paper/PMC12988649/full.md

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Source: https://tomesphere.com/paper/PMC12988649