A trial published in JAMA Internal Medicine by Lona Mody and colleagues at the University of Michigan completed a cluster-randomized trial of a bundled intervention to prevent multi-drug resistant organisms (MDRO) in nursing homes. Specifically, residents with indwelling urinary catheters, feeding tubes or both in 6 nursing homes were randomized to a targeted infection program (TIP) bundle that included (1) preemptive barrier precautions; (2) active surveillance for MDROs (baseline, day 15 and monthly at nares, oropharynx, feeding tube, supra-pubic catheter, groin, peri-rectal, and wound sites) and infections, with data feedback; and (3) nursing home staff education on key infection prevention practices, including minimum criteria for initiating antibiotics, and hand hygiene promotion. Inclusion required a signed inform consent. Six other nursing homes served as controls.
The outcomes assessed were quite broad. The primary outcome was “overall MDRO prevalence density rate, defined as each participant's total number of MDRO-positive anatomic sites across all MDROs per visit averaged over the duration of his or her participation.” This would result in residents “with persistent MDRO colonization (having) a higher prevalence than someone with intermittent or no colonization” and residents colonized at more sites (up to seven were tested) having a higher prevalence. Secondary outcomes included new MDRO acquisition and device-associated HAI both with 1,000 device-day denominators.
For the primary outcome, 27% of swabs were positive in the intervention nursing home residents while 33% were positive in the control nursing home residents. The adjusted rate ratio was significant (aRR,0.77; 95% CI 0.62 to 0.94). This outcome seems largely driven by lower methicillin-resistant Staphylococcus aureus (MRSA) colonization in residents with urinary catheters, feeding tubes, or both and lower ceftazidime-resistant Gram-negative rods colonization in residents with urinary catheters in the intervention nursing homes. However, rates of vancomycin-resistant enterococci were higher in the feeding tube requiring residents but this increase was not significant. (see Table 3) Interestingly, new MRSA acquisition rates were lower in the intervention nursing home residents (see Table 4, below) and first new catheter-acquired urinary tract infection rates were also lower in the intervention nursing home residents (HR=0.54; 95% CI, 0.30 to 0.97).
Overall, this was an important study and one that should be read closely. Clearly this was a very difficult randomized controlled trial to undertake, especially with informed consent, and the research team should be congratulated. The primary outcome of MDRO prevalence density rate is an interesting choice and the authors make a compelling argument for why they chose it. However, it is unclear if the interventions in the TIP bundle are major components in the causal pathway for limiting MDRO colonization density or reducing CAUTI. However, the lower MRSA acquisition rate in the intervention nursing homes is an important outcome and does fit with how we expect barrier precautions to work. Minor quibbles aside, this trial should be discussed widely and many components of it are worth testing in other settings in future trials.
Eli N. Perencevich, MD, ACP Member, is an infectious disease physician and epidemiologist in Iowa City, Iowa, who studies methods to halt the spread of resistant bacteria in our hospitals (including novel ways to get everyone to wash their hands). This post originally appeared at the blog Controversies in Hospital Infection Prevention.