A "fishy" situation, rare pathogen and presentation in prosthetic valve infective endocarditis

Abstract

Lactococcus garviae (L. garviae) is a gram-positive coccus belonging to the Streptococcaceae family. While primarily a pathogen in fish farms causing hemorrhagic sepsis, it can act as a rare opportunistic pathogen in humans. A 2021 case report by Bravo et al. documented less than 30 cases of infective endocarditis caused by L. garviae worldwide at that time [1]. This case report describes the 27th documented case globally and 7th documented case in the USA of L. garviae causing infective endocarditis of a prosthetic valve [1]. L. garviae is found in unpasteurized dairy products, raw fish, and meat (pork, beef, and poultry), but the route of human transmission remains unclear [3]. It seems to have a predilection for individuals with prosthetic valves, immunocompromised states, prior gastrointestinal surgery, gastrointestinal disorders (colon polyps and diverticulosis), and the use of acid-reducing medications [1-3]. Infective endocarditis is the most common systemic disease caused by L. garviae [1-4]. This report details the case of a 75-year-old male, with multiple comorbidities and risk factors for L. garviae infection who was admitted for "symptomatic anemia". High clinical suspicion, coupled with an inadequate hemoglobin response to transfusion, a normal anemia workup, and blood cultures positive for L. garviae, promoted a transesophageal echocardiogram (TEE). However, the results were negative. Consequently, an ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography scan (¹⁸FDG PET/CT) was performed. The scan revealed increased uptake in the aortic valve replacement consistent with prosthetic valve endocarditis in the setting of Lactococcus garviae bacteremia.

Keywords: Bacteremia; Cardiology; Endocarditis; Gastrointestinal disease; Gastrointestinal disorders; Lactococcus garviae; Prosthetic valve; Radiology; Symptomatic anemia.

Fig. 1

¹⁸F-FDG PET/CT axial fused image from the patient below depicts the uptake of the ¹⁸F FDG radiotracer isotope as shown by the blue arrow in the aortic valve replacement, consistent with prosthetic valve endocarditis. This intense activity shown in yellow below was present on nonattenuation corrected images and therefore, deemed not to be a valve artifact. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)