MRSA Bacteremia and Injection Drug Use: Insight From Tennessee

Bloodstream infections are ones that bring a chill to most working in healthcare and infection prevention. Such infections can be deadly and are often followed by infection prevention program surveillance efforts to keep an eye out for healthcare-associated cases. Unfortunately, the opioid epidemic has also played a role in those community-onset cases.

A recent study analyzed the increase in injection drug use (IDU) in Tennessee, which then drove a spike in bloodstream infections (BSI). The link between bloodstream infections and IDU is not new, but this particular case study sought to understand the burden of those IDU-related bloodstream infections involving methicillin-resistant Staphylococcus aureus (MRSA) using data from the National Healthcare Safety Network (NHSN). Since most hospitals are required to report laboratory-confirmed MRSA bloodstream infections, this resource was helpful. The team pulled more patient-specific data, though, through the Tennessee Hospital Discharge Data System (HDDS), which helped identify those patients with ICD-10-CM codes related to injection drug use.

The research focused on those community-onset MRSA bloodstream infections (CO-MRSA BSI), which were identified on or before day 3 of hospitalization. The MRSA bloodstream infection was classified as IDU-related if any of those visits documented in the hospital discharge data system had a diagnosis code for drug use within six months (before or after) the MRSA diagnosis. The authors note that this method has been used previously for estimating IDU in hospitalized patients with infectious diseases.

First, the investigators pulled data on 7646 MRSA bloodstream infections identified from 2015-2017. Nearly a quarter (1839, 24.1%) of these cases were related to IDU. Those patients less than 13 years of age were excluded. During this study time, overall IDU-related bloodstream infections rose by 118.9%, mostly among those who were seen in emergency departments (ie, that’s where the blood draw/culture occurred). Moreover, the authors noted that there was a statistically significant association between IDU and uninsured, white women aged 18-48 years. The median age in those with IDU-related infections was 40 years, although it was 63 years in those without IDU. A total of 61.8% of those with MRSA bloodstream infections had at least 1 IDU-related diagnosis that was documented within 6 months before or after MRSA onset.

“We postulate that Tennessee’s unique epidemiology of CO-MRSA BSIs might be reflective of geographic differences in injection drug use (IDU) practices associated with the opioid epidemic,” the authors wrote. “These patients might have clinical manifestations and risk factors that vary from those identified in previous literature. In the 2000s, opioid use was largely associated with abuse of prescription opioids, but during the past decade, the rise in opioid use and overdose deaths has been attributed to an increase in commonly injected drugs such as heroin and fentanyl.”

These findings are particularly relevant for a number of reasons. First, they offer insight into multiple susceptible populations that perhaps require additional interventions during visits to emergency departments. Since healthcare-onset MRSA bloodstream infections are tracked for hospital surveillance and reimbursement, those medical providers should be cognizant of blood cultures during the 3-day window. This is not to say that surveillance cultures be drawn, as diagnostic and culture stewardship is critical to avoiding unnecessary testing and antibiotic usage, but rather that medical providers attending to those patients with IDU-related diagnoses, be proactive in identifying symptoms of infection.