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and the spine very well.
lar infection is most common among patients with
rheumatoid arthritis and may resemble a flare of the Laboratory Findings
underlying disease. Specimens of peripheral blood and synovial fluid should
The usual presentation consists of moderate to severe be obtained before antibiotics are administered. Blood
pain that is uniform around the joint, effusion, muscle cultures are positive in up to 50 70% of S. aureus infec-
spasm, and decreased range of motion. Fever in the tions but are less frequently positive in infections due to
range of 38.3 38.9C (101 102F) and sometimes other organisms. The synovial fluid is turbid, serosan-
higher is common but may be lacking, especially in per- guineous, or frankly purulent. Gram-stained smears con-
sons with rheumatoid arthritis, renal or hepatic insuffi- firm the presence of large numbers of neutrophils. Levels
ciency,or conditions requiring immunosuppressive therapy. of total protein and lactate dehydrogenase in synovial
The inflamed, swollen joint is usually evident on exami- fluid are elevated, and the glucose level is depressed;
nation except in the case of a deeply situated joint, such however, these findings are not specific for infection,
as the hip, shoulder, or sacroiliac joint. Cellulitis, bursitis, and measurement of these levels is not necessary to
and acute osteomyelitis, which may produce a similar make the diagnosis.The synovial fluid should be exam-
clinical picture, should be distinguished from septic ined for crystals, because gout and pseudogout can
CHAPTER 20
Infectious Arthritis
resemble septic arthritis clinically, and infection and
246
a fluoroquinolone, such as levofloxacin (500 mg IV or PO
crystal-induced disease occasionally occur together.Organ-
every 24 h). P. aeruginosa infection should be treated for
isms are seen on synovial fluid smears in nearly three-
at least 2 weeks with a combination regimen of an
quarters of infections with S. aureus and streptococci and
aminoglycoside plus either an extended-spectrum
in 30 50% of infections due to gram-negative and other
penicillin, such as mezlocillin (3 g IV every 4 h), or an
bacteria. Cultures of synovial fluid are positive in >90%
antipseudomonal cephalosporin, such as ceftazidime
of cases. Inoculation of synovial fluid into bottles con-
(1 g IV every 8 h). If tolerated, this regimen is continued
taining liquid media for blood cultures increases the
for an additional 2 weeks; alternatively, a fluoroquinolone,
yield of culture, especially if the pathogen is a fastidious
such as ciprofloxacin (750 mg PO twice daily), is given by
organism or the patient is taking an antibiotic. Although
itself or with the penicillin or cephalosporin in place of
not yet widely available, PCR-based assays for bacterial
the aminoglycoside.
DNA will also be useful for the diagnosis of partially
Timely drainage of pus and necrotic debris from the
treated or culture-negative bacterial arthritis.
infected joint is required for a favorable outcome. Needle
aspiration of readily accessible joints such as the knee
may be adequate if loculations or particulate matter in
the joint does not prevent its thorough decompression.
Treatment:
Arthroscopic drainage and lavage may be employed ini-
NONGONOCOCCAL BACTERIAL
tially or within several days if repeated needle aspiration
ARTHRITIS
fails to relieve symptoms, decrease the volume of the
Prompt administration of systemic antibiotics and
effusion and the synovial white cell count, and clear bac-
drainage of the involved joint can prevent destruction
teria from smears and cultures. In some cases, arthrotomy
of cartilage, postinfectious degenerative arthritis, joint
is necessary to remove loculations and dbride infected
instability, or deformity. Once samples of blood and syn-
synovium, cartilage, or bone. Septic arthritis of the hip is
ovial fluid have been obtained for culture, empirical
best managed with arthrotomy, particularly in young
antibiotics should be given that are directed against
children, in whom infection threatens the viability of the
bacteria visualized on smears or against the pathogens
femoral head. Septic joints do not require immobilization
that are likely, given the patient s age and risk factors.
except for pain control before symptoms are alleviated
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