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Abstract:
Streptococcus
Pneumoniae is a relatively uncommon causative organism of septic
arthritis, accounting for 3 – 10 % of cases of septic
arthritis. The joints most commonly affected are knee, shoulder,
elbow and polyarticular infections1. Streptococcus
Pneumoniae infection of the SIJ in an adult is rarely reported2,
with only 1 previously reported case in the UK3. We
report a rare case of culture proven Streptococcus Pneumoniae
sacroiliac joint (SIJ) infection.
J.Orthopaedics 2008;5(1)e9
Keywords:
Streptococcus Pneumoniae; sacroiliac;
sacroilitis; septic arthitis
Case Report:
In
July 2007, a 69 year old woman presented to the accident and
emergency department with a 4 week history of gradually
worsening left leg and buttock pain. She did not report any
paraesthesia or history of recent trauma. Her past history
included cervical spine fusion, IDDM and a previous
hysterectomy. In addition she also had unexplained weight loss
of 1 stone in 6 weeks.
On
examination the patient was apyrexial. There was no obvious
deformity of the spine, no visible erythema or swelling. She was
generally tender over the lower lumbosacral region,
predominantly on the left side. Both hips were non tender
however she was unable to straight leg raise due to pain.
Neurovascular examination was normal. The rest of the
examination was unremarkable.
Blood
investigations revealed neutrophilia (white cell count 16.0 x109/l)
and raised inflammatory markers (C-Reactive Protein 150mg/l and
Eythrocyte Sedimentatio Rate 103mm/hr). All other blood tests
were normal. Provisional differential diagnoses of occult
infection, disc prolapse, multiple myeloma and bone metastases
were considered. An urgent Magnetic Resonance Image of her
lumbar spine and pelvis was arranged.
MRI
scan revealed a soft tissue mass lying anterior to the cranial
aspect of the left sacroiliac joint, measuring 7cm x 7cm x 5cm.
These findings were consistent with an abscess and sacroiliitis.
The
patient was taken to theatre for incision and drainage and
specimens sent for microscopy, culture and sensitivity. The
patient was started on broad spectrum intravenous antibiotics
until sensitivities were received.
Post-operatively
the patient remained clinically well, with her symptoms
improving significantly. Cultures grew Streptococcus
Pneumoniae, sensitive to benzylpenicillin. The patient was
commenced on high dose intravenous benzylpenicillin, following
consultant microbiology advice. The patient completed four weeks
intravenous antibiotics and two weeks oral antibiotics.
During
her inpatient stay, the patients weight loss was investigated.
CT scan of her abdomen and pelvis revealed a suspected carcinoma
of the bowel. She underwent laproscopic right hemicolectomy and
made an excellent post-operative recovery.
Three
weeks after discharge serology results were received, indicating
serotype 16f.
Discussion :
Septic
arthritis caused by S.
Pneumoniae has traditionally been thought to occur
infrequently. however literature suggests it may account for
6-10%1,4 of cases of septic arthritis, highlighting
the need for greater awareness of this causative organism. Cases
of S. Pneumoniae
sacroiliitis however, appear to be rare indeed with only 1
previously reported case in the UK3.
Previous
cases have involved children or the elderly with a background of
immunosuppression2.
S.
Pneumoniae is a gram positive diplococci commonly causing
pneumonia and meningitis in adults and otitis media in children.
Less frequently it causes other infections such as endocarditis
and septic arthritis. The presentation of a patient with S.
Pneumoniae infection may include fever, rigors, vomiting and
general systemic upset in addition to features specific to the
foci of infection.
The
principle of management for septic arthritis, regardless of the
causative organism, involves draining the joint and antibiotic
therapy5,6. Drainage can be achieved in a number of
ways, including surgical incision and drainage, arthroscopic
drainage or repeated needle aspirations. Samples from drainage
must be sent for microscopy, culture and sensitivity, and in the
meantime broad spectrum intravenous antibiotics should be
commenced. Once sensitivities are known, a long course, 4-6
weeks, of appropriate antibiotics can be prescribed, initially
intravenous for 2-4 weeks unless the patient remains ill,
followed by adequate oral therapy to complete the course7.
For
septic arthritis to develop there is usually a primary focus to
begin with, common sites for S.
Pneumoniae including pneumonia and meningitis. From there
haematogenous spread to the joint can occur. Frequently no
primary cause is identified, these infections are thought to
originate from a transient bacteraemia, or from a localised
source.
S.
Pneumoniae is a common pathological organism, so it may be
expected to cause septic arthritis more frequently than it does.
The reason for this is not clear but frequently those acquiring
it have an element of immunosuppression. Co-morbidities include
rheumatoid arthritis, lymphoma, myeloma, malignancy, HIV
infection, neutropenia, steroid treatment and diabetes mellitus,
to name a few4, 8. In the case we presented the
patient had two risk factors, diabetes mellitus and malignancy.
Prevention
of S. Pneumoniae infection involves a vaccination programme in
children and identification and vaccination of at risk groups.
Two vaccines currently exist, a pneumococcal
conjugate vaccine (PCV) containing the 7 most common serotypes,
and pneumococcal polysaccharide vaccine (PPV) containing 23
serotypes. PCV is given as part of the childhood vaccination
programme between ages 2 months and 2 years, whilst PPV is given
all patients aged 65 and over, or those aged 2 or above who are
at risk. Conditions included in the at risk group include most
chronic diseases (including diabetes mellitus) and
immunosuppression9. In the case we presented, the
serotype (16f) was not covered by either vaccination.
Conclusion
:
Streptococcus Pneumoniae remains an unusual
cause of septic arthritis of the SI joint. Management involves
drainage of the joint, followed by a long course of appropriate
antibiotics after samples have been analysed in the lab.
Prevention involves effective management of risk factors and
vaccination of groups most susceptible to the organism or that
have a higher morbidity. Cases usually involve patients
significant co-morbidity.
Reference :
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Garcia De la Torre I. Advances in the management of septic arthritis. Rheum Dis Clin North Am 2003; 29: 61-75.
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Shirtliff M E, Mader J T. Acute septic arthritis. Clin Microbiol Rev 2002; 15: 527-544
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