Levofloxacin-Resistant Streptococcus gordonii Infective Endocarditis in an Elderly Patient: A Case Report

Infective endocarditis (IE) in older adults often presents with nonspecific or subtle clinical features, which may delay recognition, especially when antibiotics are initiated before appropriate diagnostic testing. Streptococcus gordonii is a common oral organism capable of causing IE. We describe a case of IE caused by levofloxacin-resistant S. gordonii in a woman in her 90s with poor oral hygiene. She developed persistent fever after receiving empirical levofloxacin for a presumed urinary tract infection. Although recent dental procedures were absent, blood cultures obtained prior to hospital admission yielded S. gordonii. Transthoracic echocardiography revealed severe aortic regurgitation without vegetations, while brain magnetic resonance imaging demonstrated multiple embolic infarctions. The diagnosis of IE was based on the isolation of S. gordonii and clinical features consistent with the disease, including fever, severe aortic regurgitation, multiple cerebral embolic infarctions, and glomerulonephritis. The organism was resistant to levofloxacin while remaining susceptible to penicillin and ceftriaxone. Despite administration of appropriate antimicrobial therapy, the patient's condition deteriorated, and palliative care was pursued in accordance with her wishes. This case underscores two critical diagnostic and management challenges in IE among older adult patients: failure to obtain blood cultures before initiating antibiotics and the potential contribution of poor oral hygiene to bacteremia. To avoid diagnostic delays, it is crucial to obtain blood cultures prior to antibiotic administration. Furthermore, maintaining optimal oral hygiene may help reduce the risk of bacteremia.