Epidural steroid injections to treat chronic low back pain are often administered at outpatient clinics. On March 12, 2015 the Illinois Department of Public Health (IDPH) was notified of two patients with invasive methicillin-resistant Staphylococcus aureus (MRSA) infections who had undergone epidural steroid injections on February 24, 2015 at the same pain management clinic. IDPH conducted an investigation to identify additional cases, pinpoint potential infection control lapses, and implement control measures to prevent additional infections.
METHODS:
Investigators conducted a site visit to assess facility protocols and infection control practices. All patients who had injections between February 10 and March 12 were contacted via telephone or in-person. Medical records of patients with invasive MRSA infections at community hospitals were compared to clinic records. Lot numbers of medications used were collected. Clinic employees in the procedure room on February 24 underwent nasal and throat screening for MRSA colonization. Clinical specimens were submitted to CDC for confirmatory testing of MRSA isolates, pulsed-field gel electrophoresis (PFGE) analysis, and whole genomic sequencing (WGS).
RESULTS:
Between February 10 and March 12, 187 patients received injections. Four patients with procedures on February 24 and one patient with a procedure on March 3 developed invasive MRSA infections; no other infections were identified. Clinical syndromes included spinal and epidural abscesses, meningitis, and bacteremia. Incubation periods ranged from 3–95 days. PFGE patterns from the four patients treated on February 24 and one healthcare worker (HCW) were indistinguishable and were identified as USA 300-0114, and WGS results showed 0-3 single nucleotide polymorphism (SNP) differences between the HCW and four patient isolates. PFGE showed no relation between the isolate for the patient treated on March 3 and the other five isolates; WGS was not performed. Contrast packaged as single-dose had been dispensed into sterile trays and administered to multiple patients. Surgical masks were not consistently worn by staff assisting with preparation of medication. No other infections were linked to medication lot numbers.
CONCLUSIONS:
MRSA was likely transmitted from a colonized HCW to four patients during invasive injection procedures on a single day. Investigators conducting patient follow-up during outbreaks associated with steroid injections should be aware of the potential for long incubation periods. Recommendations included discontinuing the use of single-dose products for multiple patients; ensuring all personnel involved in preparation and procedures wear masks; and reviewing all infection control practices. One MRSA-colonized employee was reassigned to duties unrelated to injections.