A 43‐year‐old man presented with 5 days of fever. The patient's history began in childhood when he was told he had a heart murmur. He was in his usual state of good health until 5 days prior to admission when he felt unwell. He later noted a fever to 103.8°F, and went to an outside hospital, where blood cultures were drawn. The patient was discharged, but self‐administered clarithromycin which he had at home. He was notified that his blood cultures were positive, and presented to our hospital for evaluation. Initial culture data was unavailable at this time. On exam, the patient was febrile and diaphoretic. A 3/6 pansystolic murmur was present throughout the precordium with radiation to the clavicles and axillae. The patient was started on vancomycin and gentamicin for presumed bacterial endocarditis. The following day initial blood culture results returned with Gram‐negative rods and cefepime was added. A transthoracic echocardiogram was performed which revealed a ventricular septal defect (VSD) with left‐to‐right shunting. There was no evidence of vegetations. A transesophageal echocardiogram also failed to show vegetations. The patient's blood cultures subsequently grew Eikenella corrodens. He was discharged on intravenous ceftriaxone for six weeks.
Despite the lack of echocardiographic evidence for endocarditis, given his history and Eikenella bacteremia, a presumptive diagnosis of endocarditis was made. Reports show that 10% of patients present with negative transesophageal echocardiograms. It appears that cases that are diagnosed soon after the onset of symptoms may be caught before vegetations become visible. Only 3%–6% of endocarditis cases are caused by HACEK organisms, and although the lack of an antecedent event calls the diagnosis into question, poor dentition and recent dental work are only observed in 50% of cases. The patient's VSD puts him at risk for endocarditis, as those with an unrepaired VSD have an incidence of 22 to 24 per 10,000 patient years. The risk is higher in those with unrepaired VSD as compared to those who have undergone repair with a relative risk of 3.3. The choice of empiric antibiotic therapy in cases of suspected endocarditis is also important. It is estimated that 10% of cases are caused by gram‐negative bacteria. Guidelines suggest empiric treatment with ampicillin‐sulbactam plus gentamicin, or vancomycin plus gentamicin plus ciprofloxacin. Given the increasing prevalence of methicillin‐resistant Staphylococcus aureus, many practitioners may prefer the vancomycin regimen; however such regimens should include gram‐negative coverage until culture data is known since the dosing for gentamicin is for its synergistic effect and not gram‐negative coverage.
Patients with suspected endocarditis should be started on broad antibiotic coverage including gram‐negative bacteria until culture data is available.
To cite this abstract:Fakheri R, Adler N. Invisible Hacek Endocarditis of Native Valves. Abstract published at Hospital Medicine 2013, May 16-19, National Harbor, Md. Abstract 434. Journal of Hospital Medicine. 2013; 8 (suppl 2). https://www.shmabstracts.com/abstract/invisible-hacek-endocarditis-of-native-valves/. Accessed January 19, 2020.