A rare case of Streptococcus pluranimalium bacteremia causing infective endocarditis and brain abscess was reported in IDCases.
Infective endocarditis is an infection of the endocardium of the heart that is most commonly observed in patients with underlying risk factors. There have been few cases of infective endocarditis in humans secondary to S pluranimalium as this bacteria has been more commonly linked to illness in primarily bovine and avian species.
The investigators reported a case of a 51-year-old man, a non-intravenous drug user with a past medical history significant for mitral valve prolapse with severe mitral regurgitation who presented to the emergency department with a 3-month history of dyspnea on exertion and intermittent fevers of up to 102° F associated with chills. A review of systems was also notable for night sweats, headache, nausea, vomiting, a 15-lb weight loss, fatigue, myalgias, and arthralgias over this period.
This individual presented to his primary care physician twice over the 3-month period with those complaints and was given a 7-day course of levofloxacin each time. After completing both antibiotic courses his symptoms briefly improved and then relapsed. Upon presentation to the emergency department, his vital signs consisted of a temperature of 102.1° F, blood pressure 124/66 mm Hg, respiratory rate of 22, and an oxygen saturation of 98% on room air.
Physical examination revealed poor dental hygiene with infection of the right upper molar; tender, erythematous nodules over the left fifth finger and right hypothenar eminence, which raised concern about Osler’s nodes; and grade 3/6 holosystolic murmur at the cardiac apex. Laboratory evaluations revealed a hemoglobin 11.5 g/dl, white blood count 10.2 x 103/microL, erythrocyte sedimentation rate 47 mm/hr, and C-reactive protein 6.23 mg/dl. In addition, the patient demonstrated persistent bacteremia with blood cultures growing Gram-positive cocci in chains identified as Streptococcus pluranimalium. This bacteria subsequently showed susceptibility to ceftriaxone, ampicillin, benzylpenicillin, vancomycin, and levofloxacin.
The patient also underwent a transesophageal echocardiogram that showed an ejection fraction of 51% with severe mitral regurgitation and severe prolapse of the posterior leaflet of the mitral valve without any evidence of vegetation on the mitral, aortic, tricuspid, or pulmonary valves. A magnetic resonance imaging scan revealed a 9 mm x 8.8 mm x 7 mm ring-enhancing lesion in the left parietal lobe and microhemorrhages in the right inferior cerebellum consistent with embolic phenomena. A Modified Duke’s Criteria was conducted and the patient met 5 minor criteria, thus confirming the infective endocarditis diagnosis. The patient was started on intravenous ceftriaxone 2 gm daily for treatment.
The patient’s symptoms improved after treatment initiation, but he continued to have mild arthralgias. Clearance of bacteremia and resolution of symptoms occurred after a 4-week course of intravenous ceftriaxone. Surveillance blood cultures remained negative on follow-up and at 6-month and 1-year visits, and the patient remained asymptomatic.
The exact mechanism of infection by S pluranimalium is unknown, and there have been only 3 cases reported in the literature since 1999 regarding endocarditis secondary to infection with this pathogen. Diagnosis of infective endocarditis is frequently made using Modified Duke’s criteria. The patient had 0 major criteria and 5 minor criteria, therefore meeting the criteria for diagnosis; however, the researchers stressed that “it is crucial [that clinicians] remember that the absence of a vegetation (or other echocardiographic findings described in the major criterion) does not rule out infective endocarditis or eliminate the possibility of systemic embolism.” In this instance a thorough physical examination aided the diagnosis and the investigators believe this case may serve to increase awareness of novel pathogens emerging as a cause of endocarditis and to stress that clinical suspicion is paramount in patients with predisposing risk factors.