Anaerobic Streptococci

CASE 1

• A 55 year old woman with gallstones and recurrent right upper quadrant abdominal pains presents with a high fever and severe pain and tenderness of the liver. An ultrasound of her right upper quadrant shows a distended gallbladder and several abscesses in the liver parenchyma. The abscesses are of different sizes, and some appear to be interconnected.

• A needle aspirate of the largest abscess is obtained. The Gram stain shows Gram-positive cocci and Gram-negative bacilli of several different morphologies. A culture grows Streptococcus milleri, Enterococcus faecalis, and E. coli. A dedicated anaerobic culture also grows Bacteroides fragilis and peptostreptococcus.

Questions:

1. Which of the organisms is the anaerobic streptococcus?
2. Would it have been likely to find only this organism in the culture of the abscess?
3. In what other anatomical sites would you expect to find anaerobic streptococci? In which sites might they be part of the microflora in an abscess?

CASE 2 (see case 2 in the section on "viridans streptococci")