Introduction
Streptococcus (S.) intermedius is a catalase-negative, gram-positive
cocci, whose most isolates are nonhemolytic with small-colony-forming
species, which belongs to the Streptococcus anginosus group (SAG), which
has also been referred to as the Streptococcus milleri group, which
includes 3 organisms: S. anginous, S. intermedius, and S.
constellatus1. This bacterial group has not been
recognised as a causative pathogen. However, with the presence of
certain factors, SAG could induce noninvasive infections and also
invasive infections after getting into sterile body sites, such as the
blood and serosal cavity, which is why it could affect the tissues and
organs of several systems of the body 2.
The SAG species differ in the virulence factors that they produce.
Because S. intermedius produces sialidase and hyaluronidase, which can
destroy host tissues, converting them into nutrients for bacterial
growth, while S. constellatus produces only hyaluronidase and S.
anginous none of these 3. Probably for this reason, S.
intermedius has the ability to form abscesses in several body locations.
However, its virulence factors are unclear at present4. This feature gives it a unique distinction compared
to other alpha-hemolytic streptococcal species and makes its management
require, in most cases, surgical intervention along with antibiotic
therapy 4.
S. intermedius is part of the commensal oral flora in humans, and it is
frequently associated with brain and liver abscesses, but less
frequently with pleuropulmonary infections including pneumonia, pleural
effusion, and empyema, and in a few cases, it can also be the causal
agent of lung abscesses. 1,5. Among the risk factors
for these infections, smoking, alcoholism, dental diseases, chronic
obstructive pulmonary disease, malignant neoplasms, liver cirrhosis, and
diabetes have been described 1. Through this case
report with a literature review, we discuss an acute presentation of S.
intermedius lung abscess in a pregnant woman with radiological findings
that make it difficult to distinguish it as a lung neoplasm, empyema or
abscess.