To the Editor:
A 54-year-old black woman with hypertension, asthma/chronic obstructive pulmonary disease, serofast-positive syphilis, and polysubstance abuse was transferred from an outside hospital for neurosurgical consultation after presenting with a 4-week history of nonradiating back pain without neurological symptoms, purulent drainage from a left gluteal wound, and associated chills and malaise. She received vancomycin and underwent incision and drainage of the gluteal wound, as well as spinal imaging. Computed tomography of the spine at the outside hospital revealed a paraspinal abscess with acute discitis and osteomyelitis.
Relevant laboratory abnormalities were an erythrocyte sedimentation rate of 102 mm/h (reference range, 0–22 mm/h) and a C-reactive protein level of 114 mg/L (reference range, 0–5 mg/L). All other laboratory values were within normal limits, and HIV antigen-antibody, Quantiferon Gold, and blood cultures were negative. Magnetic resonance imaging (Fig. 1) revealed osteomyelitis with associated discitis and epidural extension at T11–T12 causing moderate spinal stenosis. There was prevertebral and paraspinal cellulitis from T9 to L1, but no abscess was visualized. Computed tomography–guided aspiration and culture at the T11–T12 level was performed by interventional radiology, after which treatment with cefepime (minimum inhibitory concentration, ≤2) and vancomycin was started. Tissue cultures grew Serratia marcescens, although blood cultures remained negative throughout the patient's hospital course.
Workup for the etiology of her osteomyelitis included transthoracic echocardiogram followed by a transesophageal echocardiogram, which revealed a 0.6 × 0.6-cm mass on the tip of the left coronary cusp of the aortic valve, which was concerning for possible endocarditis. Despite the patient's history of polysubstance abuse, she adamantly denied intravenous drug use during multiple interviews, although she did admit to 1 episode of skin popping 2 years prior to her current hospitalization. She was discharged to a subacute facility on 2 g of intravenous cefepime every 8 hours for the treatment of both osteomyelitis with discitis and presumed infectious endocarditis. Outpatient infectious disease follow-up 7 weeks after discharge showed improvement of her back pain. At that time, she was transitioned to 500 mg of oral levofloxacin daily for 2 weeks. After her initial visit, the patient transitioned her care to another outpatient infectious disease physician.
S. marcescens is a facultative, anaerobic, gram-negative, oxidase-negative bacillus that is most commonly found in water and soil.1 The first reported case of the organism infecting humans occurred in 1913 by Woodward and Clarke.1 Since then, there have been rare reports of isolated endocarditis or osteomyelitis caused by this organism. However, most of these cases of endocarditis have been seen in the intravenous drug using population,2 and most of the osteomyelitis cases have been acquired nosocomially after surgical interventions.3 To our knowledge, there have been no reports of simultaneous osteomyelitis and endocarditis.
Although infections caused by S. marcescens are rare, particularly in patients who are immunocompetent, the number of infections since 1960 has been increasing.4 This case is particularly unique in that the patient presented with combined osteomyelitis and presumed endocarditis despite having no prior health care exposures, history of intravenous drug use, or known immunocompromised state that would predispose her to such an infection. Vertebral osteomyelitis is also rare, representing only 2% to 4% of all bone and joint infections.5
This patient's presenting back pain and systemic symptoms of malaise and chills prompted an investigation into her spine as a potential source of infection. Given her lack of risk factors for spinal osteomyelitis, other sources of infection were sought, including the heart. Transesophageal echocardiogram confirmed the vegetations on the patient's aortic valve, prompting the care team to repeatedly inquire about the patient's drug history. She was very forthcoming with the information but vehemently denied intravenous drug use, stating that she only used drugs intranasally.
Treatment of S. marcescens is a challenge because of extended resistance to antibiotics including penicillins and first- and second-generation cephalosporins, as well as the organism's tendency to acquire extended-spectrum β-lactamases and carbapenemases; as such, the determination of antibiotic susceptibilities is incredibly important.6
In summary, S. marcescens osteomyelitis is a rare entity, and the combination of suspected infective endocarditis with osteomyelitis is even more uncommon. This is particularly true in this patient, who has no known risk factors for such an infection. Treatment of these infections is difficult and requires strict patient compliance, which can be difficult in the subset of patients most at risk.
Written consent was obtained before writing this letter.
Brianna L. Siracuse, MD
Thomas A. Di Vitantonio, MD
Robert Fede, MD
Department of Medicine
Rutgers New Jersey Medical School
Rajendra Kapila, MD
Department of Medicine
and Division of Infectious Diseases
Rutgers New Jersey Medical School
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: a report of seven cases. Scand J Infect Dis
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