Internal Medicine

0521779407-B01 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 20:52

216 Bacterial Arthritis

■Blood cultures positive in about 50%

■Cultures of other sites of infection

■PCR for bacterial DNA in fluid or tissue, especially for N. gonor-

rhoeae, mycobacterial or partially treated infections

Imaging

■Joint radiographs should be done early

➣Usually show only soft tissue swelling initially

➣Helpful to exclude associated osteomyelitis

➣Provide baseline to assess treatment response

■Destructive arthritis w/in days to weeks if untreated

■Bone scans can show joint inflammation in joint before radiographic

change but are nonspecific & not usually necessary

■CT & MRI can aid in diagnosis, showing local extension of infection

or presence of osteomyelitis

differential diagnosis

■Trauma: history helpful; radiograph to exclude local bone pathology

■Crystalline arthritis: gout, pseudogout; may have history of previ-

ous episodes of acute inflammatory arthritis; diagnosis depends on

seeing crystals in synovial fluid

■Initial onset of a chronic arthropathy such as RA or a seronegative

spondyloarthropathy, although onset is usually not as abrupt

management

What to Do First

■Arthrocentesis to obtain specimen to establish specific diagnosis &

determine antibiotic sensitivities, & to remove pus

■Empiric IV antibiotics based on clinical picture; consider age, risk

factors, exposure, extra-articular infections; Gram stain important:

➣Neonates: S. aureus, Enterobacteriaceae, group B streptococci

➣Children <5 yrs: H. influenzae, S. aureus, streptococci

➣Children >5 yrs: S. aureus, streptococci

➣Adolescents/adults: N. gonorrhoeae, S. aureus, streptococci,

Enterobacteriaceae

➣Prosthetic joints, recent joint procedure or surgery: S. epider-

midis, S. aureus, streptococci, gram-negative bacilli

General Measures

■Drainage of reaccumulating pus by:

➣Arthrocentesis

➣Arthroscopic lavage & debridement