Causes of infectious arthritis

Organism	Clinical clues
Staphylococcus aureus	Healthy adults, skin breakdown, previously damaged joint (eg, rheumatoid arthritis), prosthetic joint
Streptococcal species	Healthy adults, splenic dysfunction
Neisseria gonorrhoeae	Healthy adults (particularly young, sexually active), associated tenosynovitis, vesicular pustules, late complement deficiency, negative synovial fluid culture and Gram stain
Aerobic gram-negative bacteria	Immunocompromised hosts, gastrointestinal infection
Anaerobic gram-negative bacteria	Immunocompromised hosts, gastrointestinal infection
Brucellosis	Zoonosis
Mycobacterial species	Immunocompromised hosts, travel to or residence in an endemic area
Fungal species (Candida species, sporotrichosis, Cryptococcus, blastomycosis, coccidioidomycosis)	Immunocompromised hosts
Spirochete (Borellia burgdorferi)	Exposure to ticks, antecedent rash, knee joint involvement
Mycoplasma hominis	Immunocompromised hosts with prior urinary tract manipulation

Refer to separate UpToDate topic for discussion of viral causes of arthritis.

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