Non-β-hemolytic Streptococcal Bacteremia in Patients With Heart Valve Prosthesis-Is It Always Infective Endocarditis?

Background: Non-β-hemolytic streptococci are among the most common causative agents of infective endocarditis (IE). Patients with a heart valve prosthesis (HVP) have a high risk of IE. We aimed to determine the risk for IE in patients with HVP and non-β-hemolytic streptococcal bacteremia (NBHSB) and to study NBHSB relapse depending on treatment duration. Method: Adults with HVP and NBHSB from 2015 to 2018 in the region of Skåne, Sweden, were identified through the Clinical Microbiology Laboratory in Lund and evaluated in a population-based investigation. Data were collected from medical records according to a predefined protocol. Results: A total of 110 NBHSB episodes in 89 patients with HVP were included. In 40 episodes (36%), the patients had definite IE, in 69 possible IE, and 1 had rejected IE according to the European Society of Cardiology 2015 criteria. Of the 70 patients without a definite diagnosis of IE, 28 (40%) were treated with antibiotics as if they had IE. There were 7 NBHSB relapses, and 6 of these occurred in patients with possible IE. Four relapses occurred in patients who received antibiotics for <14 days. Three patients with possible IE were diagnosed with definite IE at the time of the relapse. Conclusions: Patients with NBHSB and HVP have a high risk for IE and should be thoroughly investigated. Most patients with NBHSB and HVP who fulfilled criteria for possible IE did not receive long-course antibiotic treatment. Moreover, some patients treated with a short course of antibiotics experienced NBHSB relapse.