Primary Sternal Osteomyelitis Caused by Methicillin-Sensitive Staphylococcus aureus: A Diagnosis Rare in Healthy Adults

Abstract

Primary sternal osteomyelitis (PSO) is a rare clinical entity, and usually, it is associated with predisposing factors such as intravenous drug use, diabetes mellitus, or human deficiency virus infection. In an otherwise healthy adult, it becomes an even rarer entity. Early diagnosis and treatment minimize associated morbidity, like the need for surgical debridement, longer courses of medication, and length of in-hospital stay.We describe the case of a 54-year-old man without any predisposing risk factors for PSO, who presented with chest pain, erythema, tenderness, and warmth at the right parasternal region. A non-enhanced thoracic tomography showed a 33 mm suspicious pulmonary nodule and no signs of sternum abnormalities. To better evaluate this finding, a positron emission tomography with fluorine-18 fluorodeoxyglucose was performed, showing abnormal uptake of the radionuclide at the sternomanubrial synchondrosis and no abnormal uptake at the lung parenchyma. The presence of Staphylococcus aureus in blood cultures, in conjunction with these results, supported the diagnosis of PSO. The patient completed six weeks of microbiologically oriented antibacterial therapy with complete recovery.

Culture-negative primary sternal osteomyelitis in a patient with uncontrolled type 2 diabetes mellitus

“…PSO, on the other hand, is more rare and has no identifiable primary focus of infection [4] . It is hypothesized that PSO arises via hematogenous seeding of the sternum during episodes of bacteremia [5] . There are approximately 100 cases of PSO identified in American literature [6] , and our literature review showed 6 more cases reported since 2019.…”

“…The diagnosis of PSO is based on a combination of different factors, including clinical suspicion, laboratory and microbiologic findings, and radiologic imaging [5] . The differential diagnosis for superficial chest and sternal pain is extensive, including costochondritis, cellulitis, soft tissue abscess, benign soft tissue tumors, and soft tissue or bony sarcoma [9] .…”

“…However, CT allows for superb delineation of osseous changes, and may be superior to MRI for the detection of sequestrum, foreign bodies, or intraosseous gas [13] . Moreover, CT is widely available, is typically less expensive than MRI, and can guide aspiration and biopsy [5] . CT imaging was chosen in our case due to its relative ease and availability at the time of patient presentation.…”

“…Empiric antibiotics should cover Gram-positive and Gram-negative organisms, and it is important to consider coverage for methicillin-resistant S. aureus [16] . Surgical debridement should also be considered in PSO and may be required in patients who present with subperiosteal collection or abscess, necrotic bone, or simultaneous joint infection [5] . Positive blood or wound cultures enable the identification of a causative organism, possibly allowing for de-escalation of the antibiotic regimen.…”

“…Positive blood or wound cultures enable the identification of a causative organism, possibly allowing for de-escalation of the antibiotic regimen. Patients should generally continue on antibiotic therapy for at least 6 weeks [5] . Our patient was empirically treated for Gram-positive and Gram-negative organisms with daptomycin and cefepime, respectively.…”