Sternal osteomyelitis and infective endocarditis after old trivial chest trauma in untreated diabetes mellitus: A case report

Abstract An 82‐year‐old man with untreated diabetes mellitus (DM) had anterior chest wall swelling and ulcers 2 years following blunt chest trauma. Contrast‐enhanced computed tomography revealed sternal fracture with osteolytic change and subcutaneous abscess. Blood and sternal cultures were positive for methicillin‐susceptible Staphylococcus aureus (MSSA). Transesophageal echocardiogram showed vegetation on the right coronary cusp and moderate aortic regurgitation. The patient received a diagnosis of infective endocarditis associated with chronic sternal osteomyelitis complicated by subcutaneous abscess because of MSSA. This case report showed that trivial trauma in patients with uncontrolled DM can cause chronic sternal osteomyelitis resulting in infective endocarditis.


| INTRODUC TI ON
Primary sternal osteomyelitis is a rare condition that occurs in only 0.3% of individuals with osteomyelitis. 1 Few studies have reported chronic primary sternal osteomyelitis following trivial trauma. 1,2 The occurrence of infective endocarditis with primary sternal osteomyelitis is uncommon. 2,3 Here, we describe the case of an 82-year-old man who developed infective endocarditis associated with sternal osteomyelitis 2 years after trivial chest trauma.

| C A S E REP ORT
An 82-year-old Japanese man received a diagnosis of diabetes mellitus (DM) based on a fasting blood glucose level of 145 mg/dL and HbA1c of 6.7% 13 years back and was not treated for the same.
Two years before admission, he sustained a bruise to his anterior sternum from a car accident; although he did not consult a doctor at the time, his condition spontaneously improved. Three months before admission, he experienced anterior chest wall swelling and ulcers on the sternum with exudation and consulted a dermatologist. The sternal trauma fluid revealed the presence of methicillinsusceptible Staphylococcus aureus (MSSA). The Infectious Diseases Society of America guideline has recommended a first-generation cephalosporin or antistaphylococcal penicillin for skin and soft tissue MSSA infections. 4 Unfortunately, the patient was administered 500 mg of oral levofloxacin daily for 1 week. The swelling subsequently worsened; 9 days before admission, he was unable to lift his right shoulder. The patient was subsequently admitted to our hospital. These findings met two major and one minor Duke criteria for definitive diagnosis of endocarditis. 5 The patient received a diagnosis of infective endocarditis-associated sternal osteomyelitis caused by MSSA. We consulted with an infectious disease specialist, and the patient was intravenously treated with 2 g of cefazolin every 8 hours on day 4. The patient underwent additional abscess drainage and total sequestrectomy in the sternum on days 7 and 15, respectively.
Blood culture was negative on day 8; however, AR became severe, causing hemodynamic instability and respiratory failure (Figure 2).
He underwent aortic valve replacement with a bioprosthetic valve via right thoracotomy on hospital day 38. Macroscopic findings revealed exenterated aortic valve and perforated noncoronary and right coronary cusps. On day 68, sternal closure using an advanced flap grafting was performed. Contrast-enhanced CT revealed abscess disappearance, and we completed the antibiotic therapy on day 104. The patient received 36-day cefazolin since the sternal closure was performed on day 68. It is critical but often missed by cardiothoracic surgeons to perform the culture of the infected heart valve because the American Heart Association (AHA) guidelines indicate additional antibiotic therapy for 14 days after valve replacement. 6 Unfortunately, we did not perform a culture of the infected heart valve. We administered additional antibiotics therapy for 66 days, over 14 days, after valve replacement according to the AHA guidelines. 6 The patient was transferred to a rehabilitation hospital on day 116. First, although S aureus can migrate from any type of skin breakdown, the occurrence of chronic sternal osteomyelitis after trivial trauma is extremely rare. Only two such cases have been reported, and the pathogen in both cases was S aureus (Table S1) In conclusion, physicians should consider a history of trivial trauma in the sternum in patients with uncontrolled DM because it can lead to chronic sternal osteomyelitis, which subsequently causes infective endocarditis.

ACK N OWLED G EM ENT
None.

CO N FLI C T O F I NTE R E S T
Authors declare no conflict of interests for this article.