Chapter 44: Bacterial Endocarditis

Patient Story

A 14-year-old girl with a history of mitral regurgitation that complicated rheumatic heart disease was brought in by her parents after two weeks of intermittent low-grade fevers, fatigue, weakness, arthralgias, and myalgias. On examination, she appeared ill, was febrile, and had a heart murmur. Her funduscopic examination revealed Roth spots (Figures 44-1 and 44-2). Her blood cultures grew Streptococcus mitis. An echocardiogram demonstrated a vegetation on the mitral valve. She was hospitalized and treated for bacterial endocarditis.

Introduction

Bacterial endocarditis is a serious infection that in the pediatric population is seen most commonly in patients with congenital heart disease, prosthetic valves, injection drug users, and patients with indwelling central venous catheters. The diagnosis is made based on the Duke Criteria. The rate of cure with appropriate antibiotics and surgical management, when indicated, is high, and facilitated by prompt diagnosis and vigilance in recognizing complications.

Epidemiology

• 0.34 to 0.64 cases per 100,000 patient-years.¹

• 1 case per 1000 pediatric hospital admissions.

• 46 percent of cases in ages 0 to 1, followed by 23 percent, 20 percent, and 12 percent in ages 12 to 18, 5 to 12, and 1 to 5 years, respectively.²

• 58 percent of cases in male patients.²

• 68 percent of patients hospitalized with infective endocarditis (IE) had some type of congenital heart disease.²

• 2007 AHA guidelines for IE prophylaxis have not changed IE admissions.²

Etiology and Pathophysiology

• Flow through an abnormal valve or abnormal communication between systemic and pulmonary circulation (as in various congenital heart diseases) damages endothelium.

• Platelets and fibrin adhere to damaged endothelium initiating a sterile thrombus.

• Microbes adhere to compromised endothelium during transient bacteremia.

• Common organisms include viridans Streptococci (such as Streptococcus mitis and Streptococcus oralis) Staphylococcus aureus, coagulase-negative Staphylococci, Enterococci, Candida spp, and rarely Streptococcus pneumoniae.

• Viridans streptococci are more commonly associated with rheumatic fever, unrepaired congenital heart disease, and late postoperative endocarditis.

• Staphylococcal species, including methicillin-resistant S aureus (MRSA) and coagulase-negative Staphylococci, are commonly associated with endocarditis after cardiac surgery and with prosthetic valves; S aureus is also common as a cause of endocarditis in individuals who have normal hearts and in intravenous drug users.

• Fungal causes of endocarditis, ...