Be careful about MICs to amoxicillin for patients with Streptococci-related infective endocarditis

Background: A variety of microorganisms can cause infective endocarditis (IE), with Staphylococci and Streptococci accounting for the majority of cases. Streptococci are a common cause of community-acquired IE but few studies have focused on this subgroup of endocarditis. Methods: A retrospective multicentre study was conducted between 2012 and 2017 in 12 hospital centres in France. Data were extracted from the local diagnosis-related group database and matched with microbiological results. After identification, the records were retrospectively analysed. Results: A total of 414 patients with streptococcal endocarditis were included. The patients were predominantly male (72.8%) and the median age was 73.2 years (interquartile range [IQR] 61.3-80.9). The majority of patients (70.6%) had native valve endocarditis. Embolic complications were seen in 38.8% of patients. Viridans group Streptococci (VGS) and bovis-equinus group Streptococci (BGS) accounted for 52.4% and 34.5% of isolated strains, respectively. Minimum inhibitory concentrations (MICs) of amoxicillin were <0.125, 0.125-2 and >2 mg/L for 59.6%, 27% and 1% of isolates, respectively. In-hospital mortality for patients with Streptococci-related IE was 17.8%. In multivariate analysis, the only factor associated with in-hospital mortality was MIC for amoxicillin between 0.25 and 2 mg/L (P = 0.04; OR = 2.23 [95% confidence interval (CI) 1.03-4.88]) whereas performance of cardiac surgery for IE was a protective factor (P = 0.001, OR = 0.23 [95% CI 0.1-0.56]). Conclusions: IE remains a serious and deadly disease despite recent advances in diagnosis and treatment. Adaptation of antibiotic doses to MICs for amoxicillin and surgery may improve patient outcome. (C) 2019 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.