Next-Generation Sequencing of Microbial Cell-Free DNA to Rapidly Detect Fluoribacter Bozemanae Pneumonia in an Immunocompromised Host

Abstract

Background: Fluoribacter bozemanae is an uncommon pathogen that accounts for just 3-5% of cases of pneumonia caused by the different Legionella species. The mortality rate has been reported to be up to 40%. This organism is difficult to identify, making diagnosis extremely challenging with current diagnostic modalities. Case Report: We present a case of a 75-year-old female with a history of multiple myeloma undergoing active treatment with immunosuppressive agents who presented with confusion, hypoxemic respiratory failure and sepsis. Her initial presentation was consistent with Legionella infection, however, all routine testing including a Legionella urine antigen test came back negative. A CT scan of the chest was completed which showed near complete left lower lobe consolidation concerning for pneumonia. An infectious workup was initiated. Atypical and viral pneumonia polymerase chain reaction panel was negative. Microbial cell-free DNA sequencing returned positive for Fluoribacter bozemanae, a subspecies of the Legionellaceae family that is known to cause severe pneumonia in immunocompromised hosts. This information allowed a therapy adjustment resulting in rapid improvement of our patient’s symptoms. Conclusion: In cases such as this one, the diagnosis of Legionella species is often missed due to the many challenges associated with the different testing modalities. In these circumstances, next-generation genetic sequencing can be extremely useful. Now with the increasing availability of next-generation sequencing as a microbiological diagnostic tool, we can diagnose many more infections that once would have gone undiagnosed and either untreated or delayed in treatment.