Native Aortic Valve Endocarditis Caused by Gut Bacterial Translocation Following Gastroenteritis

Native valve infective endocarditis (IE) refers to infection resulting from the seeding of bacteria onto the heart valves, usually in patients with one or more risk factors such as intravenous drug use, poor dentition or recent dental surgery, prior structural or valvular heart disease, or indwelling cardiac devices. Although viridans group streptococci (VGS) are a common cause of aortic valve endocarditis, it is uncommon for the infection to result from bacterial translocation across the intestinal mucosa during gastroenteritis. This case involves a 64-year-old female who presented with an acute onset of shortness of breath, weakness, nausea, vomiting, rigors, and night sweats lasting two to three weeks. She also reported a week of nonbloody diarrhea that has since resolved. A CT pulmonary angiogram revealed an acute pulmonary embolism (PE) in the right upper lobe without evidence of right heart strain. A transthoracic echocardiogram, obtained during the work-up for her PE, showed a mobile density on the right coronary cusp concerning for vegetation. Transesophageal echocardiogram confirmed a mobile density on the right coronary cusp of the aortic valve, consistent with a vegetation larger than 10 mm. Blood cultures grew Streptococcus oralis/mitis, and the patient was diagnosed with IE. She subsequently underwent early aortic valve replacement with cardiothoracic surgery. The source of the IE in this patient remains unclear. However, based on her history of a week of profuse, nonbloody diarrhea prior to any other symptom onset, it is likely that bacterial translocation from the gut during an acute episode of gastroenteritis was the source of the bacteremia leading to vegetation. While VGS are typical causes of IE, the infection usually originates from the oral cavity and less commonly from the lower GI tract. This patient had no recent dental procedures and no dental issues to suggest an oral route of infection. Her presentation with acute PE and subsequent diagnosis of native aortic valve endocarditis secondary to gastroenteritis was atypical, particularly as it occurred in a native valve without underlying risk factors.