HSR&D Home » Research » CDP 13-004 – HSR&D Study
Comparative Effectiveness of Strategies to Control S. Aureus Infections (CDA 11-215)
Marin L. Schweizer-Looby, PhD BS
Iowa City VA Health Care System, Iowa City, IA
Iowa City, IA
Funding Period: May 2013 - April 2018
It is unknown which strategies, and in which patient populations, work best at reducing S. aureus infections. Additionally, there is little consensus on the optimal treatment for S. aureus infections.
The three aims are: 1) Complete meta-analyses of the effectiveness of different S. aureus infection prevention strategies; 2) Compare the effectiveness of anti-staphylococcal antibiotics for the treatment of invasive S. aureus infections; and 3) Create a decision model to compare strategies to prevent and treat S. aureus infections.
Aim 1, we performed 2 systematic literature reviews and meta-analyses. The first evaluated which non-surgical patient populations would most benefit from mupirocin decolonization. The second evaluated whether universal glove use was more effective than glove use only for multidrug-resistant organism (MDRO) infected patients or standard precautions. For the meta-analyses, we conducted a systematic search to identify all publications. The pooled odds ratios (pOR) or pooled rate ratios were pooled using a random-effects model.
Aim 2, the outcomes are 30-day mortality and recurrent infection. Cox proportional hazard models were used to assess mortality hazards (stated as a hazard ratio [HR]). Optimal beta-lactam therapy was defined as cefazolin or nafcillin/oxacillin. We compared the effectiveness of different antibiotics to treat S. aureus infections.
Aim 3, we are creating a mathematical model to evaluate the effectiveness of adding mupirocin decolonization to the current VA MRSA Initiative. Data from Aim 1 is being used to parameterize the model.
Aim 1: The first meta-analysis found that mupirocin decolonization was protective for ICU patients (pOR=0.44, 95% CI: 0.26, 0.73), peritoneal dialysis patients (pOR=0.23, 95% CI: 0.15, 0.36) and hemodialysis patients (pOR=0.15, 95% CI: 0.06, 0.36). These results were published in Clinical Infectious Diseases. The second meta-analysis found that universal gloving was not more effective than current practices at reducing the incidence of MDRO acquisition or healthcare-associated infection (pooled rate ratio=0.87, 95% CI: 0.69, 1.09). These results were presented at the ECCMID conference in April 2016.
Aim 2: We created a retrospective cohort of 16,973 Veterans with methicillin-susceptible S. aureus (MSSA) bacteremia who were admitted to one of 122 VA medical centers. We found that definitive treatment with any beta-lactam was associated with a 26% decreased hazard of mortality compared with definitive treatment with vancomycin (adjusted HR: 0.74; CI: 0.61-0.90). These results were published in Clinical Infectious Diseases. Among a similar cohort of 3,303 patients who received only optimal beta-lactam treatment, we found that cefazolin use was associated with decreased 30-day mortality compared with nafcillin/oxacillin (adjusted HR: 0.74; 95% CI: 0.60-0.91). However, cefazolin was associated with an increased risk of recurrence compared with nafcillin/oxacillin (adjusted HR: 1.09; 95% CI: 0.91-1.31), although this was not statistically significant. These results were published in Clinical Infectious Diseases.
We compiled a cohort of 664 Veterans with S. aureus prosthetic joint infections (PJI) after hip or knee surgery. We compared the effectiveness of rifampin combination antibiotic therapy to antibiotic therapy without rifampin. We found that 45% of S. aureus PJI patients received rifampin therapy. Rifampin treatment was observed to have a trend towards decreased risk for treatment failure, although this was not statistically significant (adjusted HR=0.85, 95%CI 0.66-1.09). These results were presented at the ICAAC conference in September 2015. The manuscript is written and will be submitted for publication soon.
Aim 3, I am currently collaborating with my colleagues at the Salt Lake City VA to complete the mathematical model.
This study is consistent with the mission of the VHA in attempting to determine the most effective and cost-effective strategies that can be implemented by the VHA MRSA Prevention Initiative to prevent and treat S. aureus infections.
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DRA: Infectious Diseases
DRE: Epidemiology, Prevention
MeSH Terms: none