A 57 year‐old female with a history of a perianal abscess presented with fevers and chills for seven days. Two weeks prior the abscess had drained spontaneously. On admission, temperature 100.9°F, BP 104/70, HR 112/minute, and RR 15/minute. Physical exam demonstrated mild right upper quadrant tenderness and a 1‐2mm well healed scar in 6 o’clock position of her anus. Labs showed WBC 15.7/mL with 88% PMNs, ALP 202 U/mL, T bil 1.5 mg/dL, ALT 70 U/L, AST 145 U/L. Abdominal CT scan showed a 11.4 x 9 x 14 cm lobulated collection in the right hepatic lobe with satellite abscess measuring 2.4 x 2.2 x 1.8 cm in the left lobe. The patient received piperacillin/ tazobactam 3.375g IV q6(hr) and underwent percutaneous drainage of the larger abscess. Cultures of the aspirate and 1 out of 2 sets of blood cultures grew Streptococcus anginosus. Antibiotics were changed to ceftriaxone 2g q24(hr) and metronidazole IV 0.5g q8(hr). Transthoracic echocardiogram was negative for vegetation and subsequent blood culture was negative. She was discharged on the same antibiotic regimen but presented 1 week later with memory deficits. Head CT(scan) and brain MRI showed more than 10 ring‐enhancing brain lesions measuring 0.3 — 1.7 cm in the bilateral cerebral and cerebellar hemispheres, most prominently adjacent to the left ventricle with associated edema. Transesophageal echocardiogram (TEE) showed 0.7 cm vegetation on the aortic valve with a trace aortic regurgitation. Ceftriaxone was increased to 2g q12(hr). Repeat TEE 1 week later showed disappearance of the vegetation. Her symptoms improved and she was discharged. CT at 4 weeks of therapy showed interval resolution of the brain lesions and the liver abscesses.
The Streptococcus anginosus group (SAG), also known as the Streptococcus milleri group is a subgroup of viridans streptococci that consists of three distinct streptococcal species: S. anginosus, S. intermedius, and S. constellatus. Compared to other viridans streptococci,members of the SAG are more often associated with abscess formation, including liver and brain abscess through their cell surface adhesions and pyogenic extoxins but less often associated with infectious endocarditis. When endocarditis does occur, it is more common in patients with damaged or prosthetic heart valves than patients with normal native valves. A 2012 literature review identified twelve cases of disseminated pyogenic infection affecting multiple (2 or more) organs, caused by SAG, but none was accompanied with endocarditis. Our case describes a rare instance of liver and brain abscesses in the setting of infectious endocarditis by SAG.
It is important to recognize SAG as one of the causes of native valve infectious endocarditis and to search for signs of dissemination to other organs. Brain abscess should be considered in any patient with SAG bacteremia who presents with cognitive deficits. Also our case suggests the importance of performing TEE to evaluate for endocarditis for patients with SAG bacteremia.