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Incidence of MRSA Colonization in Resident Physicians 

Lexus Dickson, BS; Morgan Smith, DO; Steven Warrington, MD; Stephen Thacker, MD; Katherine Jamison, PharmD; Leslie Hart, PhD; Nayda Parisio Poldiak, MSc, PhD; Danielle Kocsis, MS; Jean Wiggins, BSPH; Amanda Janke; Scott Gutovitz, MD

Background: MRSA colonization occurs in up to 14.5% of health care workers (HCWs) and is more frequent in warmer climates as well as in the acute care setting, such as the Emergency Department.  In addition, it is much less common in healthy people.  It is unknown if the hospital work environment is contributing to MRSA colonization of healthy HCWs.  Resident physicians are a unique population as they all start employment on July 1st.  They make a good model to study MRSA colonization of HCWs as they have not been in the healthcare environment for several months prior to starting their employment.  We hypothesized that the incidence of MRSA colonization will increase in new resident physicians over the first year of their employment.

Methods: This is a prospective analysis of MRSA colonization in new resident physicians (PGY-1) of multiple specialties at three different academic medical centers in the Southern USA.  After informed consent, PGY-1 residents were enrolled and tested for MRSA in late June 2019 prior to starting any clinical rotations, and then retested every 3-4 months thereafter for 1 year.  If positive, they were treated with 2% mupirocin and retested for cure.  For comparison, upper level residents (PGY2-5) were also enrolled as a control group.

Results: 80 PGY-1 and 81 PGY2-5 residents were enrolled in the study.  The prevalence of MRSA colonization in the PGY 2-5 group was 4.94% (4/81), and for new PGY1 residents prior to starting clinical shifts in June was 2.50% (2/80), however this difference was not statistically significant (Fischer’s exact test, p=0.68).  The cumulative incidence of developing MRSA colonization for PGY1 residents over the first 4 months of their employment was 1.32% (1/76, preliminary data only).  MRSA colonization was successfully treated with mupirocin in 71.4% of cases (5/7).

Conclusions: New resident physicians tended to have a lower MRSA colonization rate versus those who had been employed in the hospital setting greater than 1 year, although this was not statistically significant.  Additionally, working in the hospital environment caused a small increase in the incidence of developing MRSA colonization over the first year of employment.  Further research is needed to determine if this is clinically relevant to the health care worker or the patients they treat.

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