Co-occurrence of Actinomyces israelii Infection and Squamous-Cell Carcinoma of the Jaw in a Kidney Transplant Patient

Introduction: Opportunistic infections are a major concern for kidney transplant patients due to immunosuppressive therapy, especially within the first year post-transplant. Common bacterial infections include urinary tract infections by E. coli, K. pneumoniae, E. faecalis, and diarrhea provoked by C. difficile. Actinomyces israelii, the causative agent of actinomycosis, is not typically associated with immunosuppressed patients. Actinomycosis is a chronic infection characterized by abscesses, fibrosis, and draining sinuses, often following mucosal disruption from dental or gastrointestinal procedures. Case Description: We present a 67-year-old male with End-Stage Kidney Disease secondary to hypertension, who underwent kidney transplantation in 2021 and was on immunosuppression with mycophenolic acid, prednisone, and tacrolimus. He was admitted for a planned surgical resection of a right oral cavity mass. Post-operatively, he required a tracheostomy and exhibited fever and leukocytosis initially attributed to malignancy. Examination showed a mildly draining surgical site of sanguinolent fluid without the typical sand-like drainage seen with Actinomycosis. Empiric antibiotics were started and later transitioned to ampicillin-sulbactam once pathology revealed squamous cell carcinoma, osteonecrosis of the jaw, and actinomycosis. The patient completed 10 days of antibiotics with resolution of infection and was discharged home. Immunosuppression was modified during admission by discontinuing mycophenolic acid to avoid delayed wound healing and other infections. Discussion: This case highlights actinomycosis as an unusual opportunistic infection in a kidney transplant patient. The diagnosis was challenging, masked by the presumed malignancy which was initially thought to be the only pathology present. Luckily, this patient was already scheduled for mass resection and margins were negative for necrosis which helped with antibiotics length of therapy. Clinicians must remain vigilant for infections like A. israelii alongside malignancy in immunosuppressed patients after kidney transplant.