A 56-year-old immunocompromised male presented with a 2-month history of a non-healing right arm ulcer, fever, and weight loss, initially treated as a spider bite. He had a history of kidney transplant and recent travel to Arizona. Biopsy revealed necrotizing granulomatous inflammation. Cultures grew suspicious Gram-negative coccobacilli, which were definitively identified as Francisella tularensis subsp. novicida by 16S rRNA gene sequencing and whole-genome sequencing. The patient was successfully treated with ciprofloxacin. This case highlights the importance of considering rare Francisella subspecies in immunocompromised patients with atypical presentations, especially those with environmental exposures.
Key note: Rare Francisella subspecies should be considered in immunocompromised patients with atypical presentations and relevant environmental exposures.