title: Does the presence of crystal arthritis rule out septic arthritis?
abstract: The objective of this study was to determine the incidence of septic arthritis in the presence of joint crystals. A retrospective study was conducted at a university tertiary care referral center. The study population included all patients with synovial fluid crystals in the joint aspirate sent to the laboratory during the 7-year study period. Septic arthritis was defined as a positive synovial culture. Of the 265 joint aspirates containing crystals, 183 (69.0%) contained gout crystals, 81 (30.6%) contained pseudogout crystals, and 1 (0.4%) contained both. Four (1.5%) of the aspirates had positive cultures. The mean synovial WBC of the 4 samples with concomitant crystals and septic arthritis was 113,000 (95% confidence interval [CI] 72,700-153,200), which was significantly higher than the entire population at 23,200 (95% CI 19,400-27,000; p < 0.01). Of note, all 4 patients with concomitant disease had significant co-morbidities and synovial WBC counts greater than 50,000. Septic arthritis and acute crystal-induced arthritis can occur simultaneously; there were 4 cases (1.5%) of concomitant disease in our study population. The presence of crystals cannot exclude septic arthritis with certainty.
authors.affiliation: Department of Emergency Medicine, St. Luke's-Roosevelt Hospital, New York, New York 10025, USA.
authors.forename: Kaushal
authors.initials: K
authors.lastname: Shah
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Spear
authors.forename: Larry A
authors.initials: LA
authors.lastname: Nathanson
authors.forename: Jon
authors.initials: J
authors.lastname: McCauley
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Edlow
mesh_terms: D017677:Age Distribution; D000368:Aged; D001170:Arthritis, Infectious / Q000175:diagnosis*; D002131:Calcium Pyrophosphate / Q000032:analysis; D002805:Chondrocalcinosis / Q000175:diagnosis*; D015897:Comorbidity; D005260:Female; D006073:Gout / Q000175:diagnosis*; D006785:Hospitals, University; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D017678:Sex Distribution; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013297:Streptococcus pyogenes / Q000302:isolation & purification; D013582:Synovial Fluid / Q000166:cytology / Q000382:microbiology; D014527:Uric Acid / Q000032:analysis
chemical_list: D014527:Uric Acid; D002131:Calcium Pyrophosphate