Background: The clinical spectrum of septic arthritis in the era of the opioid crisis is ill-defined.
Methods: This is a retrospective chart review of 1465 cases of culture-positive native joint septic arthritis at Boston teaching hospitals between 1990 and 2018.
Results: Between 1990-2008 and 2009-2018, the proportion of septic arthritis cases involving people who inject drugs (PWID) rose from 10.3% to 20% (P < .0000005). Overall, methicillin-sensitive Staphylococcus aureus (MSSA) caused 41.5% of cases, and methicillin-resistant Staphylococcus aureus (MRSA) caused 17.9%. Gram-negative rods caused only 6.2% of cases. Predictors of MRSA septic arthritis included injection drug use (P < .001), bacteremia (P < .001), health care exposure (P < .001), and advancing age (P = .01). Infections with MSSA were more common in PWID (56.3% vs 38.8%; P < .00001), as were infections with MRSA (24% vs 16.8%; P = .01) and Serratia sp. (4% vs 0.4%; P = .002). Septic arthritis in the setting of injection drug use was significantly more likely to involve the sacroiliac, acromioclavicular, and facet joints; 36.8% of patients had initial synovial fluid cell counts of <50 000 cells/mm3.
Conclusions: Injection drug use has become the most common risk factor for septic arthritis in our patient population. Septic arthritis in PWID is more often caused by MRSA, MSSA, and Serratia sp., and is more prone to involve the sacroiliac, acromioclavicular, sternoclavicular, and facet joints. Synovial fluid cell counts of <50 000 cells/mm3 are common in culture-positive septic arthritis.
Keywords: MRSA; Staphylococcus aureus; injection drug use; sacroiliac joint; septic arthritis.
© The Author(s) 2020. Published by Oxford University Press on behalf of Infectious Diseases Society of America.