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Updated: Feb 17, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Acquisition and persistence of strain-specific methicillin-resistant Staphylococcus aureus and their determinants in
Nataliya G Batina1, Christopher J Crnich2,3, Dörte Döpfer4
1Department of Industrial and Systems Engineering, University of Wisconsin-Madison, 3270 Mechanical Engineering Building, 1513 University Avenue, Madison, WI, 53706, USA. batina@wisc.edu.
Background:
Nursing home residents are frequently colonized with various strains of methicillin-resistant Staphylococcus aureus (MRSA) but the intra-facility dynamics of strain-specific MRSA remains poorly understood. We aimed at identifying and quantifying the associations between acquisition and carriage of MRSA strains and their potential risk factors in community nursing homes using mathematical modeling.
Methods:
The data was collected during a longitudinal MRSA surveillance study in six nursing homes in South Central Wisconsin. MRSA cultures were obtained from subjects every 3 months for up to one year. MRSA isolates were subsequently strain-typed by pulsed-field gel electrophoresis (PFGE), and their genetic similarity was established based on the Dice coefficients. Bayesian network analysis, logistic regression and elastic net were used to quantify the associations between acquisition and carriage of MRSA strains discriminated at 80% and 95% strain similarity thresholds and potentially modifiable resident characteristics including previous antibiotic exposure, comorbidity, medical devices, chronic wounds, functional and cognitive status and recent hospitalizations.
Results:
Absence of severe cognitive impairment as well as presence of a wound, device and severe comorbidity was associated with elevated probability of USA100 carriage although there was a variation based on the combination of those risk factors. Residents with severe comorbidity and cognitive status and presence of device and wound were identified as certain carriers of USA100 in our sample. Residents with a chronic wound were more likely to carry USA100 MRSA (OR = 2.77, 95% CI = 1.37-5.87). Functional status was identified as an important determinant of carriage of USA100 and USA300 strains. Comorbidity and cognitive status were the two factors associated with carriage of all clonal groups in the study (USA100, USA300 and USA1200).
Conclusions:
The combination of Bayesian network analysis, logistic regression and elastic net can be used to identify associations between acquisition and carriage of MRSA strains and their potential risk factors in the face of scarce data. The revealed associations may be used to generate hypothesis for further study of determinants of acquisition and carriage of selected MRSA subtypes and to better inform infection control efforts in community nursing homes.
Insights
Nursing home residents carrying methicillin-resistant Staphylococcus aureus (MRSA) strains are linked to factors like wounds and cognitive status. Understanding these associations can improve infection control for MRSA in nursing homes.
Area of Science:
- Infectious Diseases
- Epidemiology
- Mathematical Modeling
Background:
- Nursing home residents often carry methicillin-resistant Staphylococcus aureus (MRSA).
- Intra-facility dynamics of specific MRSA strains are not well understood.
- Research is needed to identify MRSA strain-specific risk factors in nursing homes.
Purpose of the Study:
- To identify and quantify associations between MRSA strain acquisition/carriage and risk factors in nursing homes.
- To utilize mathematical modeling for understanding MRSA transmission dynamics.
- To inform infection control strategies for MRSA in long-term care facilities.
Main Methods:
- Longitudinal MRSA surveillance in six Wisconsin nursing homes over one year.
- MRSA isolates were strain-typed using pulsed-field gel electrophoresis (PFGE).
- Bayesian network analysis, logistic regression, and elastic net quantified associations with resident characteristics.
Main Results:
- Carriage of USA100 MRSA was associated with chronic wounds, devices, severe comorbidity, and cognitive status.
- Functional status influenced carriage of USA100 and USA300 strains.
- Comorbidity and cognitive status were linked to all studied MRSA clonal groups (USA100, USA300, USA1200).
Conclusions:
- Mathematical modeling effectively identifies MRSA strain-specific risk factors, even with limited data.
- Findings can guide further research on MRSA acquisition determinants.
- Results support enhanced infection control efforts in nursing homes.
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