Download Infectious Sacro-Iliitis (ISI)

WScJ 1: 27-35, 2015
Infectious Sacro-Iliitis (ISI)
Ahmad Morsi, Ahmed Sallam, Abdelfattah Saoud
Department of Orthopaedic and Spine Surgery, Ain Shams University School of Medicine, Cairo, Egypt
Abstract
Infectious sacroiliitis is an uncommon disease that can affect different age groups. It is caused by multiple
pathogens with variable clinical presentations and often non-specific laboratory results. A high index of suspicion
should be maintained in patients presenting with low back or buttock pain to avoid misdiagnosis and delay in
diagnosis. Early diagnosis with effective antibiotics, for the appropriate duration and through the appropriate
route, will usually result in complete resolution with minimal chance of recurrence and complications. Surgical
intervention in the form of drainage, debridement or arthrodesis can be needed for patients refractory to
antibiotics, those with delayed diagnosis or those with generally compromised health states.
Key words: Infection, sacro-iliitis
Background
I
nfectious sacroiliitis (ISI) is an uncommon disease
of variable presentation with various causative
organisms. Pyogenic ISI (non-tuberculous, non-Brucella)
accounts for 1.5% of pyogenic septic arthritis in children
and less than 1% in adults (3,4). This is probably due to the
poor vascularisation of this joint resulting in a low risk of
infection via the haematogenous route (4).
Diagnosis is usually difficult and delayed due to clinical
heterogeneity and the lack of symptom specificity. Lack
of awareness by clinicians, variable & poorly localizing
signs of infection, frequent lack of systemic symptoms
and serological criteria of infection makes it a “diagnostic
challenge” (1-4,14).
Most observations about infectious SI are based on case
reports or small case series (4).
Hermet et al (4), in 2012, presented the largest
documented series of pyogenic ISI to date. They also
reviewed cases published since 2009 (4). Three older studies
examined isolated cases in reviews (4). The first review
reported cases collected between 1878 and 1990, the second
between 1990 and 1996, and the third between 1996 and
2009 (4). The most comprehensive review was that published
World Spinal Column Journal, Volume 6 / No: 1 / January 2015
by Bernard Zimmermann III et al (14) in 1991 in which 166
cases were reviewed (4).
Anatomy of the sacroiliac joint: Articular surfaces,
nerve & blood supply.
The sacroiliac joints (SIJ) are large central synovial
articulations with a wide range of anatomic variation in the
shape, extent of articular surface, and symmetry. Mobility
of the SIJ is subject to some controversy, but most authors
believe that there is some component of rotation around a
transverse axis through the second sacral segment. Motion
of the SIJ is greatest at birth and decreases from birth to
puberty. In women, mobility increases after puberty to
peak around 25 years of age. During pregnancy, the action
of relaxin on ligaments and periarticular structures results
in appreciable increase in sacroiliiac and pubic symphysis
mobility. In men and women, mobility decreases in the
fourth and fifth decades and is usually absent in the elderly
(14).
Innervation of the joint arises primarily from the
lumbosacral plexus, which lies directly anterior to the
joint capsule. SIJ vascularity originates from the pelvic
and paravertebral venous plexus of Batson. The extent of
vascularization of the joint has been shown to peak in the
27
Infectious Sacro-Iliitis (ISI)
second decade of life and to decline after the age of 30. The
composition of SIJ cartilage is similar to that of peripheral
joints, although unique features of its collagen organization
have been described (14).
The variable clinical pictures associated with ISI may
result from the characteristic anatomy of the SIJ. The first
two sacral roots pass in close proximity to the SIJ, with
the joint capsule adjacent to the psoas major muscle then
the peritoneum anteriorly, and the gluteal and pyriformis
muscles posteriorly. These relations might explain the
anterior inguinal or abdominal pain, and the posterior
buttocks or thigh pain depending on which part of the joint
capsule is mainly involved (3,4).
Pathogenesis: Causative pathogens
and Risk factors
Route of infection:
Infectious agents may affect the joint in the form of
reactive (immune-mediated) arthritis, or by hematogenous
spread or direct penetration into the joint (14). Most SIJ
infections appear to occur via a hematogenous spread
(bacteraemia), although the frequency of obvious preceding
infection varies (3,4,14).
Previous reports have suggested that SIJ infections have
a predilection for the iliac side of the joint, given the thicker
cartilage barrier on the sacral side. Very rarely however, the
periarticular abscess was confined to the sacrum (2).
Age and gender:
Multiple studies agree on the young age of prevalence of
pyogenic ISI. While pyogenic ISI occurs more commonly in
children and young adults, TB and brucellar ISI commonly
affects young and middle-aged adults and their incidence in
children and elderly people is low (12,14).
The mean age of the 166 cases of pyogenic SI reported by
Vyskocil et al. (12) and Zimmermann et al (14) were 22 and
20 years, respectively. Of the 343 patients in these two series,
there were only 13 (4%) who were older than 60 years of age.
It is possible that age-associated reduction in joint mobility
or vascularization may decrease the probability of bacterial
seeding of the joint space (3,4,14). Brucellar ISI was more
frequent in the age group of 25-34 years (11,12).
Gender predilection is variable in different case series.
Pyogenic ISI may be slightly higher in females (3,4), while
Tuberculous (TB) and Brucellar ISI may be more common
in males (8,9).
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During pregnancy and labour, the greater load demands
on the SIJ (increased weight and hormone-induced changes)
can explain the higher frequency of pyogenic ISI cases.
These can occur during pregnancy, in the immediate postpartum period, or following abortion. Tuberculous ISI has
also been reported in pregnant women (9).
Causative organism:
In pyogenic ISI, the definitive microbiological diagnosis
may be based on blood cultures, joint fluid by CT-guided
percutaneous puncture, or surgical specimens (4,14). When
performed, blood cultures are positive in 42% to 69% (3,4)
of adults and 45.5% of children (4). No primary source of
infection can be identified in up to 40% of cases (14).
More than 80% of reported cases of pyogenic ISI
are caused by Gram-positive microorganisms, of which
Staphylococcus aureus was by far the most common (4,14).
Since 2007, Methicillin-resistant Staphylococcus aureus
(MRSA) has been isolated as a cause of ISI (4). Streptococcal
species were the second most common organisms,
accounting for 9% of all cases. Streptococcus is the more
frequent agent when gynaecological signs are present (4).
Gram-negative infections were reported in 17% of all
cases (14). Pseudomonas aeruginosa was the commonest
Gram-negative bacillus in immunosuppressed and
hospitalized patients, and predominantly intravenous drug
users (4). Salmonella spp. was more frequent in children (4).
Fewer cases of Escherichia coli ISI were reported, usually in
conjunction with urinary tract infections (4,14). Till 2001,
there have been only 17 cases caused by Salmonella reported
in the English language (2).
In contrast to streptococcal infection which was
commonly associated with gynaecological signs of infection,
diarrhoea or digestive problems were not systematically
found when Salmonella was the causative agent (4).
SIJ involvement has been reported in almost 10-11% of
patients with skeletal tuberculosis and patients with systemic
brucellosis. Fungal sacroiliitis caused by Cryptococcus
neoformans has been reported in an immuno-suppressed
patient (14).
Side Predilection
SIJ infections are usually unilateral and affect the left
side in 60% of cases. An exception to that was a finding
in a Taiwanese study, reporting a predominant right side
affection or bilateral affection (4). Bilateral pyogenic
World Spinal Column Journal, Volume 6 / No: 1 / January 2015
A Morsi et al.
infections were reported during pregnancy (13.3% of cases)
(4). Bilateral TB infections were rarely reported in patients
with prolonged recumbency in supine position (8,9).
Risk factors:
Overall, risk factors are identifiable in 31% to 56% of
patients (4). Vyskocil et al (12) reviewed 166 reported cases
of pyogenic ISI and demonstrated that no associated factors
or source of infection were noted in 41% of patients. This
finding may even favor a delay in diagnosis (3).
In adults, the most common predisposing factors are
IV drug abuse and infections of the skin, respiratory and
genitourinary tracts. In IV drug users, the SIJ is more
commonly affected by pyogenic arthritis than any other
joint, accounting for 24% to 39% of cases of joint infections
in European heroin addicts (14).
The following risk factors are linked to ISI (1-4,8,14):
• Immune suppression (steroids, cytotoxic drugs).
• Immune deficiency (uncontrolled diabetes, HIV,
malignancy, hypogammaglobulinaemia).
• Infective endocarditis, IV drug abuse.
• Dental, cutaneous, respiratory or genitourinary
infections.
• Post-partum period (esp. after epidural anaesthesia
for labour)
• History of pelvic trauma (pyogenic / tuberculosis).
• Sacroiliac joint injections, or faulty nearby IM
injections.
• Low socio-economic status, undeveloped country
citizens (TB).
• Farming,
veterinarians,
(Brucella).
Laboratory
workers
Diagnosis:
Diagnosis of ISI represent a “diagnostic challenge” and
the delay in diagnosis of ISI can be explained by the atypical,
non-specific and variable clinical symptoms and signs. The
time to confirmed diagnosis is usually delayed reaching up
to several months in some patients (1-4,14).
Pyogenic ISI is diagnosed if there was bacteriological
proof of infection or, in the absence of pathogenic agents, if
the clinical, biological, and radiological data was compatible
World Spinal Column Journal, Volume 6 / No: 1 / January 2015
with this diagnosis and evolution was favourable under
antibiotic therapy (4).
Unilateral sacroiliitis should always be considered
infectious until proven otherwise (8).
In some patients with pyogenic ISI, diagnosis is
confirmed by prompt resolution of local symptoms and
signs as well as systemic illness following antibiotic therapy
(3). In contrast to pyogenic sacroiliitis, in which a high
degree of suspicion can be obtained from positive blood
culture results, diagnosis is much more difficult in sacroiliac
tuberculosis (8). Diagnosis of brucella ISI can be suspected
in areas in which brucella infection is endemic, and can be
confirmed by a raised brucella titre.
Clinical picture:
Two major modes of presentation of pyogenic ISI have
been defined. In the patients described by Vyskocil et al (12),
75% of the cases presented with acute onset of fever and
severe continuous lower back pain exacerbated by motion
or weight bearing and the patient may be unable to find a
comfortable position (12). Fever can be present in 35-40% of
cases (2 reports of fever in 75% of cases and 67% of pregnant
women). Other patients experience the more gradual onset
of symptoms, less pain, limping, painful hip extension and
low-grade or absent fever.
The vast majority of the reported patients with SIJ sepsis
had unilateral infection, but symptoms may be diffuse
and bilateral. Pelvic compression is usually painful. The
Gaenslen and FABER maneuvers will often localize the SIJ
as the source of pain.
In a review of 191 cases of pyogenic ISI, 24 cases
(13%) presented with acute abdominal pain which led to
laparatomy in 10 cases. Pyogenic ISI in infants and young
children may be difficult to distinguish from septic arthritis
of the hip. Anterior expansion of the SI joint capsule may
cause pressure on the iliopsoas muscle or sacral nerve roots,
leading to radiating leg pain and weakness suggestive of
lumbar disk disease (1-3,14).
The first two sacral nerves cross anterior to the sacroiliac
joint, and their irritation can cause radicular lower limb
pain and can limit straight leg raising. The joint capsule
is also bordered by the iliopsoas and piriformis muscles
anteriorly and the gluteal muscles posteriorly. Therefore,
if the joint capsule ruptures anteriorly, the irritation of the
psoas muscles might cause hip pain, limping, and flexion
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Infectious Sacro-Iliitis (ISI)
deformity mimicking hip sepsis. In approximately 10% of
all cases, disruption of the anterior capsule of the sacroiliac
joint may result in peritoneal irritation and presentation of
an acutely inflamed abdomen (3).
Brucella ISI: Turan et al (11) reported that osteoarticular
involvement (including SIJ) was more common in subacute
and chronic cases than in acute cases (presenting within 8
weeks of symptom onset). Fever, chills, shivering, excessive
sweating, muscle, and joint pain are the most common
symptoms in acute and subacute cases (3,4).
Turen et al (11) reported that the SIJ is the most commonly
affected joint by brucellosis (60.6%), and that 82.4% of
patients with brucellar ISI were bilateral. Commonly, history
included employment in farming and/or consumption of
un-pasteurized milk and dairy products, especially fresh
cheese. Hepatosplenomegaly was more markedly associated
when osteoarticular affection was evident (11).
Presentation in pediatric versus adult populations:
Children: ISI is rare in children and even more challenging
at diagnosis. Younger uncooperative children show highest
incidence in prolonged delay in diagnosis (13).
In 2007, Wu et al (13) retrospectively reviewed 33
patients (11 children; <15 yrs of age and 22 adults; >=16 yrs
of age) who had been diagnosed between 1996 and 2005
with pyogenic SI. This was a relatively large case series that
compared presentations in pediatric and adult populations.
Among the all included patients, females were attacked
more frequently than males (3: 1). One-third of patients had
concurrent infections, of which urinary tract infections were
the most common (41.6%). Secondary inability to walk and/
or pseudo paralysis should raise index of suspicion towards
SIJ affection in children (13).
Compared with adult patients, pediatric patients tend
to have fewer comorbid immune-compromised conditions,
fewer concurrent infections, more equality in gender
distribution and more presentations of weight bearing
difficulty. Staphylococcus aureus was the main blood culture
isolate from pediatric patients (80%), but only accounted for
50% of those from adult patients. Group B streptococcus and
Salmonella spp. were not uncommon in the adult patients
(13).
Differential diagnosis:
On admission, only few cases are suspected to have ISI.
Other suspected diagnoses on admission include: lumbar
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disc herniation with or without sciatica (commonest),
inflammatory and reactive sacroiliitis (Table 1), crystal
deposition arthritis (gout/pseudogout), degenerative disc
disease, spondylodiscitis, mechanical low back pain, septic
hip arthritis, psoas abscess or hematoma, sigmoiditis, sacral
insufficiency fractures or sacral metastasis (4,14).
Traumatic injuries of the SI joint are seen most
commonly after violent injuries. Metastatic carcinoma (9)
or sarcoma (12) may rarely mimic inflammatory sacroiliitis.
Degenerative changes of the SI joint have been associated
with aging (14).
Table 1: Inflammatory SIJ arthritis
Inflammatory SIJ arthritis (14):
•
•
•
•
•
•
•
Sero-negative spondyloarthritis
Rheumatoid arthritis
Familial Mediterranean fever
Hyperparathyroidism
Relapsing polychondritis
Behcet’s disease
Whipple’s disease
Bedside tests: Tuberculin test:
Tuberculin skin testing can be helpful in diagnosis,
however, a positive response is not specific for current
infection, and rarely, the test result may be negative in
active disease. A previous history of incompletely treated
tuberculosis, no matter how remote, should be highly
suggestive of infection, and should always be sought in this
context (8).
Serological testing:
Most serological tests are sensitive but non-specific in
diagnosis of ISI (14). These inflammatory markers can help
in diagnosis and in follow-up of treatment. ESR and CRP
are always elevated in all types of ISI (pyogenic, brucellosis
and TB) (1). Fibrinogen levels are often elevated (>25%
of patients) and leucocytic count can show leucocytosis
(polymorphs) in 40% of patients with pyogenic ISI (4). Still,
the leucocytic count can be within normal range in many
patients (1,2). Tuberculous and Brucellar ISI patients may
show mild anaemia of chronic disease and some may show
leucopenia. Brucellar ISI can be frequently associated with
lymphocytosis, thrombocytopenia, pancytopenia or DIC
(8,12).
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A Morsi et al.
Brucellar ISI when suspected, can be confirmed by
standard tube agglutination (STA) test. A titre > 1/160 or a
four-fold increase between 2 occasions 2-3 weeks apart are
diagnostic of brucellar infection. Moreover, hepatic enzymes
were found to be moderately elevated in cases of brucellar
ISI (21%) (12).
Bacteriological examination:
Examination of joint aspirate, abscess aspirate, blood
samples in the form of stained films and culture and
antibiotic sensitivity tests will confirm diagnosis, specify
the organism and indicate appropriate antibiotic regimen.
Gram stained films will demonstrate the causative organism
in pyogenic ISI (cocci/bacilli) and Brucella (Gram negative
coccobacilli). TB acid fast bacilli can be demonstrated using
the Ziehl-Neelsen stain (8).
Sputum and urine specimens may help guide the
diagnosis when stained films and cultures are positive.
Mycobacterium tuberculosis can be grown on specific
media in 4 to 6 weeks but treatment should be started once
clinical suspicion of TB infection is high.
If blood culture is positive for bacteraemia, (around
40% of pyogenic and less in brucella cases), joint aspiration
(arthrocentesis) may not be necessary. Otherwise, CT
or fluoroscopy guided aspirate should be obtained and
stained films and proper culture media should be used to
avoid missing atypical organisms (4,14). The frequency of
pyogenic ISI without any identified pathogenic agent has
tended to decrease over time, from 27% in the literature
review of Mancarella et al in 2009 (6) to 15.4% in the study of
Hermet et al in 2012 (4). In such cases, and in all cases while
waiting for culture results, parenteral combined regimens of
broad spectrum antibiotics should be used. The appropriate
antibiotic therapy should be started after confirmation of the
causative organism.
Turin et al (11) found that the mean time of growth of
Brucella melitensis (commonest species) in blood cultures
in patients with osteoarticular involvement (60.6% of which
were sacroiliitis) was 5.2 days, a time significantly shorter
compared to patients without osteoarticular involvement.
A definite diagnosis of brucellosis can be made by isolating
Brucella spp. from blood, bone marrow or other tissues.
However, isolation of the microorganism in blood culture
is difficult and obtaining bone marrow and tissue culture
is invasive and clinically impractical. Thus confirmation of
diagnosis is usually based on serum antibody detection (11).
World Spinal Column Journal, Volume 6 / No: 1 / January 2015
Histo-pathological examination of specimens obtained
from tuberculous ISI patients can demonstrate granulomatous changes or caseous necrosis compatible with tuberculosis. Some samples may show non-specific inflammatory
changes.
Imaging:
The availability of newer diagnostic imaging techniques
has greatly improved the ability to diagnose and assess SIJ
infections (1).
Plain Radiographs:
In the early and acute stage of pyogenic infections, plain
radiographs are usually normal (1,4), while in chronic cases,
they can show widening of the joint space, periarticular
osteopaenia, sclerosis and blurring of subchondral plate,
and erosion of the joint margins (1). However, these
abnormalities are not likely to appear until several weeks
after the onset of pyogenic infection (14). In contrast, these
findings may show on plain radiographs performed on
admission of TB SI (8,9) and in subacute and chronic cases
of brucella SI (3).
The radiographic abnormalities in sacroiliac tuberculosis
are identical to those observed in late pyogenic sacroiliitis. In
TB SI, plain radiographs obtained at admission are usually
abnormal. The majority will show joint space widening and
bony erosions of both sacral and iliac joint margins. Both
juxta-articular sclerosis or periarticular demineralization
have been reported (8).
There is no evidence from the literature that scintigraphy,
computed tomography, or magnetic resonance imaging
differentiate pyogenic from granulomatous sacroiliitis (8).
Computed Tomography:
Occasionally, CT scanning has shown changes suggestive
of septic sacroiliitis at a time when technetium scans and
plain radiographs were normal. Still, many CT scans remain
normal especially in early pyogenic ISI (3).
In advanced cases, pelvic and abdominal CT scans can
show bony changes (SI joint destruction) as well as soft
tissue and intramuscular abscesses (psoas, iliacus, gluteal,
intrapelvic) (3,4).
CT-guided aspiration (arthrocentesis) is beneficial
in specifying the causative organism in most cases and
is indicated when blood cultures fail to show the type of
organism (negative blood cultures in almost half of pyogenic
cases, and in the majority of TB and brucella cases (11).
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Infectious Sacro-Iliitis (ISI)
In chronic cases (which usually need surgery), preoperative CT can show joint space widening, sclerosis of
the margins of the joint, cavitations, sequestrum formation
and extent of bone destruction. Thus it can help decision
making as regards approach for debridement and need for
arthrodesis (1). Post-operatively, CT is useful in assessment
of bony fusion, usually when patients remain symptomatic
(1).
Scintigraphy:
Technetium (Tc-99) bone scanning is more sensitive for
the diagnosis of SI joint infection than plain radiography
and may be positive as early as 3 days after the onset of
symptoms (3). However, bone scanning may return negative
results if performed too early after the onset of symptoms
(3). Although bone scans are not specific, they may be useful
in localising the infection when no clinical localization is
possible (4). Gallium-67 citrate scanning was shown to
demonstrate uptake positivity earlier than Tc-99 scanning
in a group of drug users with septic arthritis (14).
Contrary to most other studies, Wu et al denoted that
scintigraphic bone scan has the highest sensitivity (93.3%)
and remains the image modality of choice and that when
local abscess formation is suspected, computed tomography
or magnetic resonance imaging may be the preferred method
used for examination. Skeletal scintigraphy Tc99 or Ga67
can be very helpful in diagnosis and infection localization
when febrile illness cannot be attributed to a specific body
system in a young child (13).
Bone scans have 3 main disadvantages: the inability to
differentiate infectious from non-infectious sacroiliitis, the
inability to differentiate sacroiliitis from psoas or gluteal
abscess and the inability to identify spread of the infection
from the joint into the surrounding tissues (1,3).
Magnetic resonance imaging (MRI):
MRI is the reference examination for establishing the
diagnosis of ISI. It also enables clinicians to assess whether
the infection has spread to the adjacent muscular structures
(4).
MRI can provide more diagnostic accuracy in pyogenic
sacroiliitis than CT or radionuclide scanning (3). It can
show bone marrow edema, fluid and pus collections
inside and adjacent to the joint (gluteal, iliacus, psoas,
pyriformis, intrapelvic). Gadolinium (Gd-DTPA) can show
enhancement in the SI joint space, adjacent bone marrow
(usually more extensive on the iliac side), and muscles (1,3).
32
In the chronic phase, MRI can show periarticular bone
marrow reconversion, replacement of articular cartilage by
pannus, bone erosion, subchondral sclerosis, joint space
widening or narrowing and ankylosis (1).
Hermet et al (4) recommended that MRI of the lumbar
spine and SI should be systematically performed in a febrile
patient with lumbogluteal pain, particularly in the case of
pregnancy. MRI signal anomalies persist for several months,
even when clinical and biological improvement appears
promising (4).
Klein et al stated that in six septic SI joints studied, all
had positive MRIs, five had positive gallium scans, three had
positive CT scans and one had a positive technetium scan
(5).
Murphey et al showed that MRI was superior to CT for
evaluation of cartilage integrity and osseous erosions in
patients with inflammatory and infectious sacroiliitis. MRI
saves the patient exposure to ionizing radiation and is thus
beneficial in evaluation of pregnant women (7).
Although there are no typical MRI features differentiating
infectious from non-infectious sacroiliitis (4), findings
favouring the diagnosis of infectious sacroiliitis were:
unilateral disease and prominent soft tissue and marrow
edema adjacent to the SI joint (14).
Recently, Positron emission tomography (PET/CT)
with fluorine-18 fluorodeoxyglucose appeared to be an
interesting technique for the very early diagnosis of ISI, even
before MRI reveals any abnormalities (4).
Treatment:
ISI presents a diagnostic rather than a therapeutic
problem, because the timely administration of antibiotics
usually leads to resolution without surgical intervention in
the majority of cases (3).
Antibiotic therapy choice:
If the infection is diagnosed at an early stage, empirical
combination of broad-spectrum antibiotics should be
parenterally administered until blood or joint aspirate
culture results are available (3).
Once the diagnosis is confirmed and the causative
organism is specified, culture specific parenteral antibiotic
therapy should be started until symptoms and signs
significantly subside. Afterwards, patients can be discharged
home on the appropriate oral antibiotic regimen which can
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A Morsi et al.
continue for weeks to months and are not stopped until the
inflammatory markers have returned to normal.
If culture results are negative, empirical anti-Staph
aureus antibiotics (in non-addicted population), should
be administered (3,4). In the case of failure to improve
symptoms and signs within 48 hours, anti- Gram-negative
bacilli antibiotics should be added, in line with the SPILF
(Société de Pathologie Infectieuse de Langue Française)
recommendations for spondylodiscitis (4). Table 2 shows
suggestions for specific effective antibiotic combinations:
For Brucellar ISI, Turan et al (11) recommended double
or triple antibiotic combinations depending on the clinical
signs and complications. This included double antibiotic
combination of rifampicin 600 mg/day and doxycycline 200
mg/day; with streptomycin one g/day and doxycycline 200
mg/day or triple antibiotic combination with rifampicin 600
mg/day, doxycycline 200 mg/day and streptomycin one g/
day (21 days) (11).
For Tuberculous ISI: Triple antibiotic combination
(2 first line and 1 second line drugs) is prescribed for the
first 2 months followed by at least 7 to 10 months of dual
combination (2 first line drugs). First line drugs include:
Rifampicin and Isoniazid. Second line drugs include
Pyrazinamide, Ethambutol and Streptomycin
Duration of antibiotic therapy:
There are no clear guidelines in the literature indicating
the optimal duration of intravenous and oral antibiotic
therapy. Most authors suggest a minimum of 2-3 weeks
intravenous and 3-6 weeks oral antibiotics in cases of
pyogenic ISI (3,4,14).
Hermet et al stated that “it seems reasonable to
propose parenteral treatment for 2 weeks followed by oral
treatment for 6 weeks in the case of pyogenic SI, which is
in accordance with the SPILF recommendations for the
treatment of infectious spondylodiscitis” (4). However,
British recommendations for the treatment of infectious
spondylodiscitis favour parenteral treatment for 3 weeks
followed by oral treatment for a total of 6–12 weeks. Hermet
et al (4) noted that antibiotic therapy for more than 6 weeks
does not reduce the risk of relapse. Therefore, there appears
to be no justification in prolonging treatment beyond 6
weeks (4).
M.-S. Wu et al 2007 recommended IV antibiotics in
children for at least 20 days to prevent relapses (13).
For brucellar ISI, Turan et al recommended that treatment
should continue for 3 months in cases of osteo-articular
brucella involvement (of which ISI represented 60.9%) (11).
For Tuberculous ISI, treatment should continue for 9 to
12 months. Few studies have continued therapy for only 6
months with favourable outcomes.
Resolution of infection:
Infection of the SIJ is considered to be healed by the
disappearance of clinical symptoms (pain, local tenderness,
fever, etc.) and normalization of laboratory parameters of
infection (WBC, CRP and ESR) (1).
If parenteral antibiotics fail to show appreciable
improvement in the patient’s signs and symptoms within
48 hours, surgical drainage and debridement should be
considered. This is true for pyogenic and brucellar SI.
Response to antibiotic treatment in tuberculous SI is usually
slow as the disease itself is usually of chronic course.
Surgical treatment:
Indications for surgical drainage include abscess
formation, evidence of contiguous osteomyelitis, and
sequestrum of necrotic bone, septicaemia, neurological
deficits and failure to respond to antibiotic therapy within
48 hours (1,2,4,14). In such cases, surgical drainage will
almost always lead to complete the resolution of infection. It
is to be stated that before the antibiotic era, septic sacroiliitis
Table 2: Antibiotic Suggestions for different pathogens.
Pathogen
Staph. aureus:
MRSA (Coagulase negative):
Antibiotic Combinations
Rifampicin, oxacillin, ofloxacin
Vancomycin
Amoxicillin+/-Clavulanic acid, Gentamycin, Ceftriaxone, Ofloxacin,
Streptococci:
Cefotaxime
Pseud. aeruginosa: (IV drug abusers till culture) Tazocilline, Ciprofloxacin, Colistin, Ceftazidime, Amikacin.
E. coli:
Amoxicillin + Rifampicin
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Infectious Sacro-Iliitis (ISI)
Figure 1: Treatment algorithm in infectious sacroiliitis.
produced large abscesses and had a reported 30% to 40%
mortality rate (2).
Surgical intervention included debridement with or
without joint arthrodesis. The surgical approach was either
posterior, anterior or combined anterior and posterior.
The localisation of the infection (abscess and soft tissue
infiltration) as demonstrated by MRI dictated the operative
approach (1). If there is evidence of abscess formation
posterior to the joint, or osteomyelitis or necrotic sequestrum
of bone within the joint, an incision over the posterior
aspect of the SI joint will allow full access for drainage of
the abscess and debridement of necrotic bone and debris.
In cases in which the distended SI joint capsule protrudes
anteriorly into the pelvis, the retroperitoneal and retrofascial
spaces must be explored (14).
Postoperative treatment included culture-based
antimicrobial therapy or broad-spectrum antibiotic therapy
when no organism was isolated, for 6 weeks in non-specific
infections and 6–12 months in tuberculous infections (1).
The postoperative immobilisation period depended
on the general condition of the patient and the operative
technique (1).
34
Ahmed et al studied 22 patients with ISI (tuberculous
and pyogenic) who needed 24 surgeries and demonstrated
that surgical outcome was favourable and that 2 patients
required revision surgery to induce fusion after infection
has recurred after complete resolution of infection (1). Their
complications also included delayed wound healing in three
cases and chronic pain in three cases (1).
There is debate over whether to perform arthrodesis of
the joint or to limit surgery to drainage of the abscess and
debridement of the joint. Ahmed et al (1), recommended
that the operative management of SIJ infections consists of
debridement in cases of acute soft tissue infection or cases
of mild bone destruction and that joint arthrodesis should
be performed in generally ill patients even with mild joint
destruction as well as in patients with chronic joint affection.
This will help early assisted mobilization. Figure (3) shows
an algorithm Suggested by Ahmed et al (1) for surgical
decision making in cases of ISI.
If SIJ stabilization is needed, as in cases where primary
arthrodesis is indicated, or cases when chronic SIJ pain results from joint damage after infection, a minimally invasive
procedure using with titanium bi-iliac screws and transverse
World Spinal Column Journal, Volume 6 / No: 1 / January 2015
A Morsi et al.
rods can be used. This technique (The novel pelvic Internal fixator) has been introduced by Saoud and Reda (10) in
2011 and was primarily indicated for stabilizing transforamenal sacral fracture
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World Spinal Column Journal, Volume 6 / No: 1 / January 2015
Manuscript submitted January 27, 2015.
Accepted January 31, 2015.
Address correspondence to: Abdelfattah Saoud, Department of Orthopaedic and
Spine Surgery, Ain Shams University School of Medicine, cairo, Egypt
email: [email protected]
35