The Journal of the Arkansas Medical Society Med Journal Jan 2020 | Page 14

Case Study
by Edward Yang, MD; 1 Tristan Washington, MD; 2
Gloria Sam, MD; 3 Michael Macechko, MD 4
Chief Resident, UAMS Northwest Family Medicine Residency; 2 Hospitalist, Lake Charles Memorial Medical Center;
3
Family Physician, Ysleta Clinic, El Paso, Texas; 4 Faculty, UAMS Northwest Family Medicine Residency
1
Abscess of the Mediastinum
Caused by Streptococcus Anginosus
Introduction
S
treptococcus anginosus is commonly
identified in the mouth, gastrointestinal
tracts, and vagina as part of the normal
flora but has been noted to play a role in
oral infections. However, more evidence is start-
ing to show that more significant infections can
occur throughout the body, including abscess
forming respiratory infections. Differentiation
from contaminate or causative agent can make
diagnosis challenging. Treatment is typical of
other abscess forming infections, and can include
surgical drainage and antibiotics.
Case Presentation
A 25-year-old female presented to urgent
care with shortness of breath and chest discom-
fort. Symptoms began one week prior as “gas and
bloating.” There she was diagnosed with bronchi-
tis and reflux and sent home with a Z-Pak and
omeprazole.
She began developing worsening migraines
the next day, followed by mid-sternal chest pain
and shortness of breath. She presented at the
emergency department that day with rust-col-
ored mucus; acute worsening chest pain; and
significant difficulty breathing associated with
lightheadedness, palpitation, nausea, and chills.
Symptoms mildly improved with ibuprofen she
took that morning.
Upon examination by the admission team,
she had a fever of 103.6º F, heart rate of 137, BP
of 128/71, respiratory rate of 22, and respiratory
rales with SpO2 of 91%. The patient was alert and
cooperative with no physical distress. Her arteri-
al blood gas showed pH of 7.43, pCO2 34, O2 sat
94%, HCO3 22. Her white blood count was 21.2
with a procalcitonin of 0.33. A CTA of her chest
was ordered by emergency physicians, and the
vRad read showed possible paraesophageal me-
diastinal right lower lobe mass with low density
foci seen in the second-order branches of pulmo-
nary arteries concerning for pulmonary emboli.
162 • The Journal of the Arkansas Medical Society
The initial read also suggested lymphoma as a
possible consideration. X-ray showed a post-obstructive pneumonia
along with worsening respiratory status.
Patient was given doses of Levaquin and
meropenem as well as fluid resuscitation in the
emergency department for meeting initial cri-
teria of sepsis. Given the patient’s presenting
symptoms, history, and initial examination and
workup, pulmonary emboli was considered
highly possible. Due to this, she was started on a
heparin drip while she was admitted and further
work-up was pursued. Oncology was consulted as lymphoma re-
mained high in the differential diagnosis. The on-
cology noted that if the patient did have lympho-
ma, a high-grade malignancy should be suspect-
ed and treatment should begin as soon as pos-
sible. Cardiothoracic surgery was consulted to
perform a right thoracotomy to obtain a second
biopsy of the mass. The results revealed necrotic
lung tissue with fibrin filling airspaces and associ-
ated pleuritic and adjacent necrotic debris. Acute
and chronic inflammation was noted along with
reactive fibrosis, but no evidence of malignancy
was noted. A Gram stain highlighted Gram-posi-
tive cocci with necrotic debris. Cultures obtained
from biopsy grew Streptococcus anginosus in the
aerobic cultures with no growth in anaerobic and
fungal cultures as well as a negative AFB smear
and culture.
Additional initial work-up included blood
cultures and coagulation panel as well as a uri-
nalysis. The final read of the initial CTA chest
showed a large subcarinal, right paraesophageal,
right lower lobe soft tissue mass that partially
encased the right lower lobe bronchovascular
structures. There was also noted narrowing of
the right mainstem and right lower lobe central
bronchi. No central pulmonary emboli noted on
final read. It was, however, again noted that lym-
phoma should strongly be considered, with other
neoplasms not excluded. Pulmonology had been
consulted and, following along with patient,
agreed that a pulmonary emboli was less likely
given updated findings. Lymphoma remained
high on the differential, and an endobronchial
ultrasound biopsy was considered as the appro-
priate step for continued evaluation. The heparin
was discontinued in preparation of biopsy.
The biopsy obtained from the EBUS re-
vealed no immunophenotypic evidence of
lymphoproliferate disorder. Lymphoid tissue
was present, but no granuloma was indicated,
and the test did not reveal any neoplasm with
low cellular material, ultimately being consid-
ered nondiagnostic. Results from other tests
were beginning to come in. The initial blood cul-
tures were negative on both counts. Urinalysis
was negative as well for infection. The patient’s
white blood cell count continued to fluctuate
throughout this time but remained elevated,
and she remained intermittently febrile as well.
She was started on Unasyn after repeat chest
Infectious disease was consulted and the
diagnosis of mediastinitis with mediastinal ab-
scess secondary to Streptococcus anginosus was
made. A culture showed moderate growth of
Streptococcus anginosus, an organism typically
considered to be part of the flora in the human
oral cavity as well as the gastrointestinal tract.
The patient was switched to ceftriaxone 2g IV
QD and clindamycin 90mg IV Q8h and continued
showing improvement. She was discharged with
ceftriaxone 2g/50 ml IV daily that she gave herself
using her PICC line and clindamycin 150 mg, two
pills every eight hours for a total of six weeks.
Discussion
Streptococcus anginosus, also known as the
S. milleri group, was first described by Guthof in
1956 and named in honor of microbiologist W.D.
Miller. It is part of a subgroup of viridans strepto-
cocci which also includes S. intermedius and S.
constellatus. As previously mentioned, it is part
of the normal flora of the human oral cavity and
gastrointestinal tract, but has also been isolated
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