P239 - UNUSUAL PRESENTATION OF A PEDIATRIC INFECTIVE ENDOCARDITIS

Case background: A previously healthy, unvaccinated 11-year-old girl presented with asthenia, a 2.2 kg weight loss over a month with a recent dental extraction and an episode of viral gastroenteritis. Her primary care physician referred her to a pediatrician because of normocytic anemia and elevated ferritin. Chest radiograph and electroencephalogram were normal, and abdominal ultrasonography showed a spleen at the upper limit of normal size. She reported a single day of low-grade fever (38°C) a few days before the pediatrician consultation. Blood cultures were obtained and additional laboratories revealed an elevated CRP and ASLO. The only notable signs on examination were digital clubbing (noticed by family since the past two weeks), tachycardia, a hyperdynamic precordium, and a new-onset grade II/IV systolic-diastolic heart murmur maximal at the apex. She was then transferred to our tertiary-care pediatric hospital.
Two sets of blood cultures, obtained 36 hours apart, turned positive for Gram-positive cocci in chains, and intravenous cefotaxime and gentamicin were started. The primary identification was Streptococcus species. Initial echocardiogram demonstrated vegetations on the anterior and posterior leaflets of the mitral valve (major vegetation measuring 3.3 on 2.3 mm), moderate to severe acquired mitral regurgitation, mild dilation of the left atrium and ventricle, and an otherwise structurally normal heart. A comprehensive workup for infective endocarditis (IE) including brain MRI, ophthalmology consultation and thoraco-abdominal imaging was performed, although the patient had no systemic embolic event signs. Brain MRI showed bilateral microembolic events with secondary microhemorrhages, with no recent ischemic event on diffusion-weighted imaging. Abdominal imaging revealed a left renal infarction and two arterial aneurysms on a right colic and a splenic arterial branch, compatible with mycotic pseudoaneurysms. The antibiotic regimen was changed to penicillin G and gentamicin 48 hours after admission, as the Streptococcus was sensitive to penicillin.
An urgent surgical resection of mycotic pseudoaneurysms and total splenectomy was performed as they had progressed under treatment. Repeat cardiac imaging (trans-thoracic and transesophageal echocardiogram (TTE,TEE) (fig 1) and cardiac computed tomography (CCT)) over the following days demonstrated progression to severe mitral regurgitation. The first TEE raised concern for a perivalvular phlegmon at the base of the left atrial appendage, corroborated on CCT, showing a hypodense area in the mitral-aortic and paravalvular region. It also described a hypodense area in the anterolateral portion of the ascending aorta, suspected of being an embolized vegetation, not seen on subsequent TTE and TEE. A cardiac surgery was performed following the progression of mitral regurgitation, the left heart location of the vegetation, the suspected paravalvular phlegmon, and the occurrence of systemic embolic events. She underwent vegetations resection and posterior mitral leaflet reconstruction with an autologous pericardial patch (fig 1). Postoperative TEE showed no residual vegetations, decreased mitral regurgitation to mild and normal ventricular function. Her hospital stay was prolonged due to an intestinal obstruction secondary to an adhesive band. She underwent adhesiolysis. In the following days, she also developed vaccine-associated attenuated varicella after receiving the routine vaccinations post-splenectomy, managed with valacyclovir.
The causative pathogen proved to be a challenge to identify and identification of Streptococcus gallinaceus was achieved through ribosomal RNA gene sequencing. Gram-positive cocci were identified on cultures of resected pseudoaneurysms but not on mitral valve vegetations. Following cardiac surgery, TTE remained stable. After four weeks on penicillin G and gentamicin, the antibiotic regimen was changed to ceftriaxone in anticipation for outpatient parenteral antimicrobial therapy (OPAT). However, repeat brain MRI a month after the initial imaging showed multiple new microembolic phenomenon and a new microaneurysm on head angioCT. This evolution of cerebral involvement prompted numerous team discussions, and a consensus was reached on continuing intravenous antibiotic therapy for six weeks starting from the date of the last new lesion on cerebral imaging. The microaneurysm remained stable and ultimately regressed over the next weeks on subsequent brain MRIs. The patient was discharged on OPAT for the last two remaining weeks of treatment and had a favorable clinical evolution.

Management Challenges: IE in children is a rare entity, even more so in children without congenital heart defects, proven the main risk factor in current literature. Our patient is unique as she also had no other inherent risk factor, such as permanent intravenous line or a state of immunodeficiency.
Streptococcus gallinaceus has only been described once in adult literature for causing IE. It is a germ typically associated with poultry with a tropism for the heart. The previously described case had an epidemiologic risk factor of contracting the bacteria whereas our patient did not, and is, to our knowledge, the only pediatric case reported in the literature.
Our case highlights the crucial importance of a thorough systemic workup in the presence of IE. While she had no neurologic symptoms, cerebral imaging showed multiple micro-embolic events and was determinant in guiding her treatment regimen. Factors commonly associated with an increased embolic risk are vegetations on a native valve, left heart lesions, vegetations measuring >10mm and a S. Aureus infection. Embolic events increase morbidity in IE and cerebrovascular events are the most frequent. It is interesting to note that digital clubbing was noted on physical examination, as it is a sign associated with IE. Maintaining a high index of clinical suspicion is essential in the presence of secondary signs and subtle changes upon examination, even in the absence of a clear history of fever.
In our case, the initial decision not to undergo an emergency surgery was based on the small size of the vegetations, the absence of hemodynamic compromise, the rapid sterilization of blood cultures on day one of antibiotics, and the risk of damaging the native valve by operating in a highly inflammatory context. It was also a challenging decision, as she had recently undergone a surgical mycotic aneurysm resection and had cerebral involvement for which a necessary anticoagulation for bypass could have been dangerous. Indications for surgical intervention are mainly based on experts' consensus and must be individualised for each patient.