(62-RES) Double Valve Endocarditis by Streptococcus anginosus of Unknown Origin

Clinical Scenario or Case: A 40-year-old male with history of hypertension was admitted to the hospital for two weeks of intermittent night sweats and dyspnea. Initial presentation was remarkable for 1st degree heart block on ECG, leukocytosis, elevated troponin and D-dimer, and evidence of kidney and liver impairment. Physical exam was notable for pre-tibial pitting edema and jugular venous distention. CTA chest was negative for pulmonary embolism. Transthoracic echocardiogram revealed vegetation on the aortic valve and ejection fraction of 25%. Blood cultures grew Streptococcus anginosus (SAG). Antibiotics were transitioned from intravenous vancomycin and ceftriaxone to only ceftriaxone per Infectious Disease.
His persistent 1st degree AV block raised concern for annular abscess. Transesophageal echocardiogram revealed vegetation on a bicuspid aortic valve with perforation of an infected leaflet and small vegetation on the mitral valve; no abscess was seen. Dental exam by OMFS ruled out odontogenic infection as a source.
The patient underwent mechanical aortic valve replacement and mitral valve repair. Surgical tissue culture grew Streptococcus viridans. He was fitted with a cardioverter-defibrillator for severe heart failure due to non-ischemic cardiomyopathy. He was discharged in good condition with plan to complete four weeks of IV ceftriaxone from the time of surgery.

Evidence/Literature Review: Woo et al (2004) and Tran et al (2008) report on the spectrum of SAG infections in patients with and without risk factors.
Pilarczyk-Zurek et al. (2022) describes SAG as an emerging opportunistic pathogen with proper microbiological diagnostics still being developed.

Unique Aspects of Case: SAG rarely causes endocarditis. It is an emerging opportunistic pathogen with molecular techniques being developed to detect and study its virulence.

Recommendations/Conclusions: SAG is a human commensal that can cause purulent infections but rarely endocarditis. It is challenging to detect but more cases are being reported due to newer testing techniques. Patients should be assessed for immune competence and malignancy when SAG infection is confirmed.