Overcoming diagnostic challenges of Abiotrophia defectiva endocarditis using MALDI-TOF MS: The first reported case in an adolescent with VSD and RSoV from Indonesia

Background: Abiotrophia defectiva, a fastidious nutritionally variant streptococcus (NVS), accounts for only 1%–2% of infective endocarditis (IE) cases worldwide and presents a formidable diagnostic challenge. We report the first documented case of Abiotrophia defectiva IE in Indonesia, involving a 15-year-old male with a ventricular septal defect (VSD) and a ruptured sinus of Valsalva (RSoV). The patient presented with a four-month history of fever and cachexia, with echocardiography revealing 0.99 cm vegetation. Although standard subcultures initially yielded no growth, enriched media eventually produced pinpoint colonies after 48 hours, supported by a positive satellitism test. Definitive identification was subsequently achieved via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with 99.9% confidence. While early surgical intervention is often the standard for NVS infections, our patient showed remarkable clinical improvement by day eight of a targeted ampicillin and gentamicin regimen. This robust response permitted the completion of a full six-week antibiotic course, allowing cardiac surgery to be deferred until the infection had resolved. This case highlights the essential function of MALDI-TOF MS in detecting fastidious pathogens and illustrates that assertive, focused medical intervention can successfully stabilize high-risk pediatric patients for elective surgery.