Prosthetic valve endocarditis presenting with back pain alone: A case report

Abstract We report a case of a 64‐year‐old woman with a past medical history (PMH) of prosthetic valve replacement 7 months prior to admission, who presented with only right back pain. Physical examination revealed one conjunctival spot hemorrhage and a mild systolic murmur. Blood cultures were positive for methicillin‐resistant Staphylococcus epidermidis. Trans‐esophageal echocardiography revealed aortic valve vegetations; hence, a diagnosis of prosthetic valve endocarditis (PVE) was made. Clinical presentation of infective endocarditis varies and sometimes mimics that of polymyalgia rheumatica. The patient was diagnosed as PVE considering the whole clinical picture including the patient's PMH, physical examination, and blood cultures.


| INTRODUC TI ON
Infective endocarditis (IE) is mentioned as an important candidate in the differential diagnosis of a variety of symptoms. Fever is reported to be seen in 90% of cases.1 IE is also known to cause musculoskeletal symptoms, and the frequency is about 44%.2 Clinical presentation of polymyalgia rheumatica (PMR) sometimes mimics that of IE because PMR causes musculoskeletal pain, typically in middle-aged and elderly women. 3 We report a case of a middle-aged woman with prosthetic valve endocarditis whose complaint was back pain alone without fever.

| C A S E REP ORT
A 64-year-old woman experienced right back pain, which appeared 6 days prior to admission (PTA); she visited the emergency outpatient unit of our hospital 5 days PTA. Her right back pain was around the right costovertebral angle, and the pain did not migrate. She had no fever or any other symptoms. She had an aortic valve replacement for severe aortic stenosis 7 months PTA. She did not have any postsurgical complications, and cefazolin was used for 3 days during the perioperative period. Her body temperature was 36.9°C; blood pressure was 114/74 mm Hg on the right arm and 114/81 mm Hg on the left arm. On physical examination, conjunctival hemorrhage or cardiac murmur was not appreciated. A laboratory test revealed that white blood cell (WBC) count was elevated to 8,830/µL, and C-reactive protein (CRP) level was elevated to 10.12 mg/dL (Table 1).
In the emergency unit, we were concerned about aortic dissection, infected arterial aneurysm, and purulent arthritis; hence, enhanced CT of the chest and abdomen was performed; however, there were no abnormal findings. Considering PMH and physical examination, we performed blood cultures. Four days PTA, methicillin-resistant Staphylococcus epidermidis (MRSE) was detected from two sets of blood cultures. We recommended hospitalization, but she refused and insisted on going home. We repeated blood cultures and let her return home. No antibiotics were started. MRSE was positive in two sets of the repeated blood cultures; hence, she was admitted to our hospital.
On admission, her body temperature was 36.1°C. On physical examination, we confirmed one punctate spot hemorrhage in the palpebral conjunctiva and a systolic murmur (grade 2/6) at the left sternal border. Costovertebral angle tenderness, spinal tap pain, and rash on her trunk, fingers, or toes were not appreciated. A urinalysis revealed that there were no bacteriuria, pyuria, and hematuria.
Although PMR was an important differential diagnosis from the chief complaint of right back pain in the patient, prosthetic valve endocarditis (PVE) was more likely considering the PMH of aortic Vancomycin was started immediately on day 1. Aminoglycoside was resistance to MRSE in sensitivity testing. Though the repeated blood cultures on day 5 were positive, they turned negative on day 8. We considered that the bacterial burden decreased, and rifampicin was added on day 13. On day 19, vancomycin was switched to teicoplanin because of leukopenia, thrombocytopenia, and fever, and rifampicin was discontinued because of the subsequent rash.
On day 20, we performed blood cultures, and they were negative.
We considered that aortic valve re-replacement was relatively indicated because the size of the vegetation did not change in the repeated TEE on day 19 even though the size was not >10 mm.
However, we needed to postpone the surgical procedure due to leukopenia and thrombocytopenia possibly caused by vancomycin infusion. We performed aortic valve re-replacement on day 33.
Because the postoperative clinical course was good, the patient was discharged on day 50.

| CON CLUS ION
In this case, the patient presented with musculoskeletal manifestations alone, which made it difficult to make a diagnosis. However, we

CO N FLI C T O F I NTE R E S T
The authors have stated explicitly that there are no conflicts of interest in connection with this article.