Vital Signs: Trends in Staphylococcus aureus Infections in Veterans Affairs Medical Centers — United States, 2005–2017

Weekly / March 8, 2019 / 68(9);220–224

On March 5, 2019, this report was posted online as an MMWR Early Release.

Makoto Jones, MD1,2; John A. Jernigan, MD3; Martin E. Evans, MD4; Gary A. Roselle, MD5; Kelly M. Hatfield, MSPH3; Matthew H. Samore, MD1,2(View author affiliations)

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Summary

What is already known about this topic?

Staphylococcus aureus is an important cause of health care–associated infections and accounts for significant morbidity and mortality.

What is added by this report?

During 2005–2017, U.S. Department of Veterans Affairs medical centers across the United States experienced a sharp decline in S. aureus infections following introduction of a multifaceted infection control intervention. Most reductions were explained by decreases in methicillin-resistant S. aureus (MRSA). Decreased MRSA transmission likely played a substantial role.

What are the implications for public health practice?

These findings offer important insights informing S. aureus prevention strategy. Effective prevention strategies require a multifaceted approach, including efforts to prevent transmission of MRSA as well as efforts directed at infection prevention.

Abstract

Introduction: By 2007, all Department of Veterans Affairs medical centers (VAMCs) had initiated a multifaceted methicillin-resistant Staphylococcus aureus (MRSA) prevention program. MRSA and methicillin-susceptible S. aureus (MSSA) infection rates among VAMC inpatients from 2005 to 2017 were assessed.

Methods: Clinical microbiology data from any patient admitted to an acute-care VAMC in the United States from 2005 through 2017 and trends in hospital-acquired MRSA colonization were examined.

Results: S. aureus infections decreased by 43% overall during the study period (p< 0.001), driven primarily by decreases in MRSA, which decreased by 55% (p< 0.001), whereas MSSA decreased by 12% (p = 0.003). Hospital-onset MRSA and MSSA infections decreased by 66% (p< 0.001) and 19% (p = 0.02), respectively. Community-onset MRSA infections decreased by 41% (p< 0.001), whereas MSSA infections showed no significant decline. Acquisition of MRSA colonization decreased 78% during 2008–2017 (17% annually, p< 0.001). MRSA infection rates declined more sharply among patients who had negative admission surveillance MRSA screening tests (annual 9.7% decline) compared with those among patients with positive admission MRSA screening tests (4.2%) (p< 0.05).

Conclusions and Implications for Public Health Practice: Significant reductions in S. aureus infection following the VAMC intervention were led primarily by decreases in MRSA. Moreover, MRSA infection declines were much larger among patients not carrying MRSA at the time of admission than among those who were. Taken together, these results suggest that decreased MRSA transmission played a substantial role in reducing overall S. aureus infections at VAMCs. Recent calls to withdraw infection control interventions designed to prevent MRSA transmission might be premature and inadvisable, at least until more is known about effective control of bacterial pathogen transmission in health care settings. Effective S. aureus prevention strategies require a multifaceted approach that includes adherence to current CDC recommendations for preventing not only device- and procedure-associated infections, but also transmission of health care–prevalent strains.