Unmasking Metastatic MRSA Infection: A Case Report of Persistent Bacteremia with Multiple Secondary Sites in a Pacemaker Patient

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) bacteremia poses a significant clinical challenge, particularly in patients with implantable cardiac electronic devices (CIEDs).It is associated with a high risk of metastatic complications such as infective endocarditis, osteomyelitis, and sepsis.Accurate identification of the primary and secondary infection sites is essential for guiding management.We report a case of persistent MRSA bacteremia complicated by septic pulmonary emboli and vertebral osteomyelitis without imaging evidence of device-related infection. Case PresentationA 67-year-old man with type 2 diabetes, Charcot foot with chronic osteomyelitis, and chronic kidney disease presented with fever and gastrointestinal symptoms.A dual-chamber pacemaker had been implanted five months prior.Laboratory tests revealed leukocytosis, elevated CRP (30.91 mg/dL), and PCT (31.77 ng/mL).Multiple blood cultures confirmed persistent MRSA bacteremia.Given the device history, infective endocarditis was suspected.However, transthoracic and transesophageal echocardiography were negative.The persistence of bacteremia prompted further investigation for deep-seated infection and the need for aggressive source control.Total-body CT revealed bilateral septic pulmonary emboli and a chronic subdural hematoma.PET/CT showed no uptake at the pacemaker site but revealed hypermetabolism at D11, right ankle/foot, and spleen, suggestive of spondylodiscitis, osteomyelitis, and reactive splenic hypermetabolism.The patient was treated with linezolid, daptomycin, and ceftaroline, with resolution of bacteremia. ConclusionThis case illustrates the potential for occult metastatic MRSA infection in the absence of echocardiographic or device evidence.Clinicians should maintain a high level of suspicion for hidden sources.Multimodal imaging remains critical in the diagnostic workup and targeted treatment.