A Rare Case of Staphylococcus carnosus Bacteremia and Discitis

Spinal discitis osteomyelitis is commonly caused by hematogenous spread of Staphylococcus aureus to the disc space. Coagulase-negative Staphylococcus species, particularly Staphylococcus carnosus has not been reported as the cause before. We report the case of an 84-year-old male patient with a medical history of hypertension and coronary artery disease who presented with a complaint of lower back pain for two weeks before presentation. MRI of the lumbar spine showed findings of marrow edema and T1 hypointensity of the L3 -4 vertebral bodies, raising suspicion for discitis and osteomyelitis. An extensive work-up for infection was initially negative, and the patient was treated with broad-spectrum IV antibiotics for six weeks; however, two months after completion of the IV antibiotics therapy, his symptoms recurred. He then presented back to the hospital with worsening lower back pain and weakness and was found to have Staphylococcus carnosus bacteremia. The patient was treated with IV daptomycin and IV cefazolin, followed by oral doxycycline, with improvement in his symptoms. To our knowledge, this is the first reported case of Staphylococcus carnosus bacteremia resulting in discitis and osteomyelitis. This case highlights the importance of keeping coagulase-negative Staphylococcus species, such as Staphylococcus carnosus, as causative pathogens for discitis osteomyelitis, even in immunocompetent patients. This case also underscores the need for a prolonged course of antibiotics to prevent the recurrence of infection and related morbidity and complications.