Pneumococcal Endocarditis in Alaska Natives

BACKGROUND: Streptococcus pneumoniae is an uncommon cause of infective endocarditis (IE). We studied the presentation, microbiologic characteristics, and outcome of nine cases of S pneumoniae IE during a 12 1/2-year period in a population of 75,000 indigenous Alaska Natives (ANs), who have documented high rates of invasive pneumococcal disease. METHODS: Fifty-six cases of IE occurred in ANs statewide during 1978 through 1990. Medical records of all nine confirmed cases of S pneumoniae IE were reviewed. Incidence rates for S pneumoniae IE and all IE were calculated. RESULTS: Alaska Natives experience S pneumoniae IE as a fulminant illness, with acute aortic valve insufficiency (100%) frequently requiring emergent valve replacement, S pneumoniae meningitis (56%), and death (33%). No patient with S pneumoniae IE had known preexisting heart disease, and the most common underlying disease was alcoholism (56%). Pneumonia was diagnosed and embolic complications were suspected in 33%. All five S pneumoniae isolates examined were penicillin sensitive and were of serotypes included in the pneumococcal vaccine. Pneumococcal IE accounted for 15.8% of all IE diagnosed in ANs. Age- and sex-adjusted incidence rates for IE of all causes and S pneumoniae IE were 8.5 and 1.5 per 10(5) persons per year, respectively. During 1986 through 1988, 4.3% of AN adults diagnosed with S pneumoniae bacteremia developed S pneumoniae IE. CONCLUSIONS: Pneumococcal endocarditis in all but one AN case required emergent valve replacement and had a 33% mortality. The annual incidence rate of S pneumoniae IE in this population was five to 37 times higher than contemporary rates elsewhere. Increased efforts to prevent pneumococcal disease in ANs appear warranted. Clinicians everywhere should anticipate the possible development of S pneumoniae IE in adult patients with pneumococcal sepsis, especially with meningitis, even with previous vaccination and prompt adequate antimicrobial therapy.