An immunocompromised pediatric patient, post-renal transplant, presented with fever, abdominal pain, and bloody stools, initially diagnosed with invasive fungal disease (IFD) due to Rhizopus microsporus. Despite antifungal therapy, the patient developed concomitant bacteremia with Mycetohabitans rhizoxinica, an endosymbiotic bacterium of R. microsporus, identified via 16S rRNA gene sequencing from blood cultures. This unusual co-infection highlights the complex challenges in managing opportunistic infections in vulnerable patients. The patient's condition required broad-spectrum antibiotics alongside antifungals, eventually leading to clinical improvement.
Key note: Concomitant bacterial and fungal infections, especially involving endosymbionts like M. rhizoxinica with R. microsporus, should be considered in immunocompromised patients with persistent sepsis.