Household risk factors for colonization with multidrug-resistant Staphylococcus aureus isolates

PLoS One. 2013;8(1):e54733. doi: 10.1371/journal.pone.0054733. Epub 2013 Jan 24.

Abstract

Antimicrobial resistance, particularly in pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), limits treatment options and increases healthcare costs. To understand patient risk factors, including household and animal contact, potentially associated with colonization with multidrug-resistant MRSA isolates, we performed a prospective study of case patients colonized with MRSA on admission to a rural tertiary care hospital. Patients were interviewed and antimicrobial resistance patterns were tested among isolates from admitted patients colonized with MRSA in 2009-10. Prevalence of resistance was compared by case-patient risk factors and length-of-stay outcome among 88 MRSA case patients. Results were compared to NHANES 2003-04. Overall prevalence of multidrug resistance (non-susceptibility to ≥ four antimicrobial classes) in MRSA nasal isolates was high (73%) and was associated with a 1.5-day increase in subsequent length of stay (p = 0.008). History of hospitalization within the past six months, but not antimicrobial use in the same time period, was associated with resistance patterns. Within a subset of working-age case patients without recent history of hospitalization, animal contact was potentially associated with multidrug resistance. History of hospitalization, older age, and small household size were associated with multidrug resistance in NHANES data. In conclusion, recent hospitalization of case patients was predictive of antimicrobial resistance in MRSA isolates, but novel risk factors associated with the household may be emerging in CA-MRSA case patients. Understanding drivers of antimicrobial resistance in MRSA isolates is important to hospital infection control efforts, relevant to patient outcomes and to indicators of the economic burden of antimicrobial resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Drug Resistance, Microbial
  • Family Characteristics*
  • Female
  • Humans
  • Length of Stay
  • Male
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Methicillin-Resistant Staphylococcus aureus / growth & development*
  • Microbial Sensitivity Tests
  • Middle Aged
  • Nutrition Surveys
  • Prospective Studies
  • Risk Factors
  • Staphylococcal Infections / microbiology

Grants and funding

Research was supported by grants from the Johns Hopkins Center for a Livable Future (http://www.jhsph.edu/clf/) and the Heinz Foundation (http://www.heinzfamily.org/aboutus/philanthropies_02.html). AEP and MFD were supported by Johns Hopkins Center for a Livable Future Predoctoral Fellowships. Additionally, MFD was supported by a Sommer Scholarship. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.