Case presentation
A 56-year-old woman presented to hospital with progressively worsening
left upper quadrant and flank pain, which had persisted following a
mechanical rotational injury to the thoracic spine sustained four weeks
prior. This was initially diagnosed as musculoskeletal pain secondary to
injury by her general practitioner, however her symptoms continued to
worsen despite resting and avoiding further mechanical aggravation.
Her medical history was significant for seronegative rheumatoid
arthritis, for which she took leflunomide 10 mg daily and methotrexate
20 mg weekly with folic acid supplementation for the last two years, and
prednisolone at a stable dose 2.5 mg daily. She had also been commenced
on subcutaneous tocilizumab 162 mg weekly, three months prior by her
rheumatologist.
She also had a recurrent Bartholin cyst infection for the preceding six
weeks, from which microbiological swab samples taken had cultured
methicillin-sensitive Staphylococcus aureus (MSSA). This
had been managed by her general practitioner with short courses of
amoxicillin-clavulanic acid – including most recently a five-day
course, completed two weeks prior to presentation. Her immunosuppressive
therapy was withheld for the preceding two weeks but she continued low
dose prednisolone.
She did not report any adverse reaction to amoxicillin-clavulanic acid
and had also tolerated this previously for other indications. She did
not have any known allergies. She did not start any new herbal or over
the counter medications, or prescribed medications, except for
tocilizumab.
She did not have any urinary symptoms, other infective symptoms, nor a
history of renal stones or gallstones. She did not have any prior
history of immunodeficiency, hyposplenism, diabetes mellitus,
endocarditis or other recent systemic infection. She did not have any
history of intravenous drug use, excessive alcohol use, prostheses or
implants. She did not have any significant or severe infections in the
preceding two years while taking methotrexate and leflunomide.
On examination, she was febrile but haemodynamically stable. She had
left upper quadrant abdominal tenderness and guarding on palpation, and
reduced breath sounds with dullness on percussion over the left lung
base. She did not have any new rashes, arthralgia or active
tenosynovitis. Blood investigations revealed elevated inflammatory
markers with a CRP of 286.2 mg/L and neutrophilia of 10.17 x
109/L. Her renal function was normal with no
electrolyte derangement. Her liver function tests were unremarkable.
Computerised Tomography (CT) of the abdomen revealed findings concerning
for a subcapsular splenic abscess and a left-sided empyema (Figure 1).
These findings were new compared to a CT performed four weeks prior at
the time of the original injury.
Splenic abscess drainage was performed under ultrasound guidance,
revealing frank pus with heavy growth of MSSA. Video assisted
thoracoscopy (VATS) and washout of the left-sided empyema and pleural
effusion was performed, with MSSA again isolated on two pleural biopsy
specimens. Blood cultures were negative for any growth. A transthoracic
echocardiogram was normal with no evidence of vegetations or valvular
abnormalities. A nuclear medicine bone scan did not demonstrate any
evidence of focal osteomyelitis.