Abiotrophia defectiva infective endocarditis: a systematic review of published case reports

Background Abiotrophia defectiva (AD), a fastidious and virulent pathogen, rarely causes infective endocarditis (IE). AD-related IE, termed ADIE, remains poorly characterized due to limited robust clinical data. This study synthesizes global case reports to clarify the characteristics and management of ADIE. Methods We systematically searched PubMed, Web of Science, CNKI, VIP Database, and Wanfang databases up to October 28, 2025. Definitive ADIE cases meeting the IE criteria at the time of publication and with microbiological confirmation of AD were included. The 2023 European Society of Cardiology (ESC) IE diagnostic criteria were reapplied to assess potential bias. Patient-level data were extracted and analyzed descriptively. Results Fifty-four patients (from 51 articles) had a median age of 36.6 years (IQR 16.0–53.5), 61.1% were male. Underlying cardiovascular disease (42.6%, 22.2% congenital) and a history of oral procedure or infection (27.8%) were common. Mitral valve involvement was most frequent (59.3%). Misdiagnosis or diagnostic delay occurred in 18.5% of cases. Among patients who received both transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), TEE detected vegetations missed by TTE in 20.0%. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identified AD in 16.7% of cases. Recovery was documented in 21/21 patients whose regimens included vancomycin; however, all received combination therapy and/or surgery, and none received vancomycin monotherapy, so the independent effect of vancomycin could not be assessed. The most frequently used regimen was a β-lactam plus gentamicin, with documented recovery in 27/28 patients (96.4%); this proportion is descriptive only and cannot be attributed to the regimen itself. Overall, 70.4% underwent surgery (66.7% cardiac surgery; 5.6% craniocerebral surgery, with one overlap). Only one in-hospital death was recorded among the published cases because of poor general condition. Conclusions ADIE predominantly affects young males and a history of heart disease or oral procedures and is frequently misdiagnosed. Diagnosis is aided by TEE, blood cultures, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Although surgical rates are high, reported short-term outcomes in published cases appear favorable, this evidence is of very low certainty because of publication, reporting, and survival bias, and long-term outcome data remain inadequate.