# Case report: The value of early application of mNGS technology in the diagnosis and treatment of severe Legionnaires’ disease: reports of two cases with different outcomes

## TL;DR

This case report shows how early use of mNGS can improve outcomes in severe Legionnaires’ disease by enabling faster diagnosis.

## Contribution

The paper presents two case studies demonstrating the clinical utility of mNGS in diagnosing Legionnaires’ disease at an early stage.

## Key findings

- mNGS confirmed Legionnaires’ disease diagnosis from bronchoalveolar lavage fluid in two patients.
- Early detection via mNGS led to successful treatment in one patient but not in the other due to delayed diagnosis.
- mNGS is shown to be a valuable tool for rapid pathogen identification in severe Legionnaires’ disease.

## Abstract

Legionnaires’ disease has a high clinical mortality rate, and early diagnosis and treatment are critical. Increasing evidence shows that metagenomic next-generation sequencing (mNGS) has excellent potential for the early identification of pathogens. To help clinicians better recognize Legionnaires’ disease in its early stage and to illustrate the diagnostic value of mNGS technology, we reviewed and summarized two cases of severe Legionnaires’ disease.

We selected two patients with severe Legionnaires’ disease who were admitted to our department in recent years. We discuss experience with them and the shortcomings in their treatment by summarizing their medical history, disease evolution, tests, and diagnostic and therapeutic processes.

In both patients, the diagnosis of Legionnaires’ disease was confirmed through analysis of the bronchoalveolar lavage fluid (BALF). The middle-aged male patient was cured and discharged due to early detection and diagnosis. The elderly immunocompromised patient died due to a delay in diagnosis.

This study highlights the importance of the early recognition and diagnosis of severe Legionnaires’ disease and the advantages of mNGS in identifying the pathogen.