Introduction
Streptococcus intermedius is a beta-hemolytic, non-motile,
catalase-negative, gram-positive member of the Streptococcus anginosus
group (SAG), along with S. anginosus and S. constellatus [1,2]. This
group is part of the normal human microbiota in the respiratory,
gastrointestinal, and genitourinary tracts [1]. They can cause
purulent infections and abscesses in the heart, brain, liver, lungs,
spleen, peritoneum, and appendix [1,3]. S. intermedius is the most
pathogenic of the group, having significantly longer hospital stays
compared to S. anginosus and significantly higher mortality rates than
S. constellatus [1, 4]. Its high-grade pathogenicity allows it to
cause an abscess in multiple sites, particularly the brain and liver due
to its apparent tropism to these sites [5,6]. A 2020 study that
collected data on patients with culture-positive SAG from the bacterial
laboratory database of the Affiliated Hospital of Jining Medical
University Hospital and Jining No. 1 People’s Hospital showed that the
three different organisms in this group were predominantly found in
different age groups and different locations [7]. S. interermedius
was mostly found in patients aged 65 years old and above and was more
likely to produce cranial infections [7]. It is more commonly seen
in males, with a male: female ratio of about 2:1, and the highest number
of reported cases are in the United States [1]. S. constelatus was
mostly found in patients aged 35-54 years old and was more likely to
produce chest infections, and S. anginosus was mostly found in patients
aged 18-34 years old and was more likely to produce perianal abscesses
[7].