Microbes Causing Spinal Epidural Infection in Patients Who Use Drugs

The incidence of spine infections has increased due to the surge in injection drug use driven by the opioid epidemic. Few recent studies have evaluated the microbiology of spinal epidural infections among people who inject drugs compared to the microbiology of such infections among the general population.

We performed a retrospective chart review to identify patients with a spinal epidural abscess or phlegmon unrelated to recent spine surgery between 2015 and 2023.

Of 346 initial records, 277 met inclusion criteria for demographic analyses. Of the 229 patients with microbiologic results, details regarding possible drug use were available in 227 patients. Patients with no documented history of drug use were categorized as non-PWUD, while patients who use drugs (PWUD) were separated based on whether drug use was active or not. Patients with prior histories of injection or noninjection drug use were categorized as nonactive PWUD, while those with injection or snorting drug use reported in the past 3 months were categorized as active PWUD. Thirty-nine percent of patients with spinal epidural infection had substance use disorder. Most patients with monomicrobial cultures were infected with gram-positive, aerobic bacteria (86%). Active PWUD were more likely to have methicillin-resistant Staphylococcus aureus compared to non-PWUD (36% vs 13%, respectively, P = .002). Nonactive PWUD were more likely to have non-Escherichia coli gram-negative bacterial infections than non-PWUD (18% and 4.4%, respectively, P = .01).

More than 1 in 3 patients with a spinal epidural infection unrelated to recent surgery had substance use disorder. These patients are more likely to have infections due to MRSA and gram-negative bacteria other than E coli such as Serratia marcescens.