Group B Streptococcal Endocarditis in Children Beyond the Neonatal Period

Lancefield group B Streptococcus is a recognized pathogen in the neonatal period causing meningitis and bactermia.1 It is an important cause of puerperal sepsis and is being reported with increasing frequency as a significant pathogen in the elderly, mainly in patients with underlying diseases such as diabetes mellitus, malignancy, alcoholism, intravenous drug abuse, and pharmacologic immunosuppression.2 Infective endocarditis caused by group B streptococci is a rare condition, seen mainly in adults,3 and to our knowledge only four cases have been reported in children beyond the neonatal period.4-7 We report a case of group B streptococcal endocarditis of the mitral valve in an 8-year-old child, and the pertinent medical literature is reviewed. Case report. A 8-year-old Qatari male was admitted to Hamad General Hospital in March, 1996, with a 2-week history of fever, polyarthralgia and easy fatiguability. There was no history of recent dental manipulation, surgical procedure or cardiac disease. On examination he looked toxic, with a temperature of 40.4°C, pulse rate 110/min and blood pressure 120/70 mm Hg. Examination of the heart revealed a grade 3/6 pansystolic murmur over the apex and radiating to the axillae. The spleen was just palpable and examination of the joints was unremarkable. Laboratory investigation revealed the following: hemoglobin 11.5 g/dl, white blood cell count 12 100/mm3, platelets 76 000/mm3, erythrocyte sedimentation rate 40 mm in the first hour. Chest radiograph, liver and renal function tests were normal. A transthoracic echocardiogram revealed moderate mitral regurgitation and a large pedunculated vegetation measuring 18 by 11 mm attached to the anterior mitral valve leaflet (Fig. 1). Two blood cultures grew group B Streptococcus susceptible to penicillin. The MIC of the isolate for penicillin was <0.03 μg/ml. The isolate was not serotyped. Diagnosis was infective endocarditis of the mitral valve and the patient was given intravenous penicillin G, 2 million units every 4 h, and gentamicin, 50 mg every 8 h. He responded well to treatment and became afebrile after 4 days. Routine follow-up echocardiogram 10 days after initiation of antibiotic therapy revealed disappearance of the mitral valve vegetations. A computed tomographic scan of the brain to exclude a silent embolization was normal. Gentamicin was given for 2 weeks and penicillin was continued for a total of 6 weeks after which the patient was discharged home in good condition.Fig. 1: Two-dimensional echocardiogram showing a large (18- by 11 mm) vegetation attached to the anterior mitral valve leaflet (arrows). aMVL, anterior mitral valve leaflet; AO, aorta; LA, left atrium.Review of the literature. Four cases of group B streptococcal endocarditis in children beyond the neonatal period have been reported in the literature.4-7 The important clinical features of these cases together with our case are shown in Table 1. Ages ranged from 1.5 months to 13 years. Three were three females and two were males. One patient had preexisting ventricular septal defect, and the other four had no previous cardiac abnormality. The tricuspid valve was involved in two patients, the mitral valve in two and the pulmonary and aortic valves in one each. One patient had combined mitral and aortic involvement. One patient had concomitant rheumatic fever, proved by histologic examination of the heart at necropsy (Case 2). The presentation was subacute in three patients and acute in two. Vegetations in the involved valve were demonstrated by two dimensional echocardiogram in all patients. The vegetations were more than 10 by 10 mm in three patients. Embolization to the lung occurred in one patient. All five patients received antibiotic therapy. In one patient antibiotics were not specified. In three patients penicillin was used either alone or in combination with gentamicin or streptomycin. In the fifth patient ampicillin and gentamicin was the antibiotic regimen. Surgery was done in two patients; in one it was for removal of the vegetation, while in the other patient the reason was not specified. Four patients survived, and one died 1 week after start of treatment because of complete heart block.TABLE 1: Summary of clinical features of patients with group B streptococcal endocarditis Discussion. Infective endocarditis is an uncommon manifestation of group B streptococcal disease with approximately 85 cases reported in the English medical literature.6-8 It is a disease of the elderly with 45% of cases having been reported in those 60 years of age or older. Underlying heart disease is found in more than one-half of cases. An underlying condition such as diabetes mellitus, malignancy, alcoholism, cancer, pregnancy, intravenous drug abuse and genitourinary disease is present in the majority of cases. There is no sex predilection and the onset of illness can be acute or subacute. Left sided involvement predominates. The organism does not produce fibrinolysin, which may account for the large crumbling vegetations and frequent major systemic emboli seen in these patients. Penicillin with or without an aminoglycoside continues to be the preferred regimen for the treatment of group B streptococcal endocarditis. Surgery may be needed to remove pedunculated vegetations; however, the timing of surgery, whether after the first or second embolic episode, remains controversial.9 The overall mortality for all treated patients is ∼50%. Mortality in those treated with antibiotics alone is ∼60%, while in those treated with both antibiotics and surgery it was 29%.6 Group B streptococcal infective endocarditis in the pediatric age group is rare, with only 10 cases reported in the English literature.4-7,9-11 4 of them beyond the neonatal period.4-7 Our patient is the fifth case. Previous valvular heart disease and other predisposing conditions were not present in any of the patients. The disease may by acute or subacute, involve any valve and produce large pedunculated vegetations which can break and produce emboli. Anemia, thrombocytopenia and elevated erythrocyte sedimentation rate were present in all patients in whom the tests were done. Mortality in these five patients was 20%. Of the three patients treated with antibiotics alone one died (33%); the two patients who had surgery survived. The lower mortality seen in children could be related to the lack of prior valvular abnormality and other predisposing conditions. Generally accepted indications for surgical intervention during active infective endocarditis include refractory congestive heart failure, uncontrolled infection, more than one serious systemic embolic episode, local suppurative complications such as perivalvular abscess, valve dysfunction and fungal endocarditis. Because the number of patients is small, we cannot recommend that all patients with group B streptococcal endocarditis undergo early surgery, although this has been suggested by some authors.6-8 One possible approach in patients with large vegetations is to repeat the echocardiogram after 10 to 14 days; if the vegetation is enlarging or if embolization has occurred, surgery is recommended. One interesting feature in our patient was the complete disappearance of the large mitral valve vegetation 10 days after starting antibiotics. One possible explanation for this observation is detachment of the vegetation into the systemic circulation; however, the child did not have clinical evidence of embolization and a computerized tomographic scan of the brain was normal. In conclusion group B streptococcal endocarditis is unusual in infants and older children, with only five cases beyond the neonatal period reported including our patient. The disease is similar to that seen in adults except in children it is not associated with the risk factors seen in adults and it carries a lower mortality. A combination of antibiotic therapy and surgery in patients with embolization or enlarging vegetations on repeat echocardiogram is recommended. Hussam Alsoub, M.D. Fatima Najma, M.D. Andrej Robida, M.D., Ph.D., F.A.C.C.