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Updated: Oct 27, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Ward-level factors associated with methicillin-resistant Staphylococcus aureus acquisition-an electronic medical
Zaw Myo Tun1, Dale A Fisher2,3, Sharon Salmon4
1Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
Background:
Methicillin-Resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide. Intrahospital transfers may impact MRSA acquisition risk experienced by patients. In this study, we investigated ward characteristics and connectivity that are associated with MRSA acquisition.
Methods:
We analysed electronic medical records on patient transfers and MRSA screening of in-patients at an acute-care tertiary hospital in Singapore to investigate whether ward characteristics and connectivity within a network of in-patient wards were associated with MRSA acquisition rates over a period of four years.
Results:
Most patient transfers concentrated in a stable core network of wards. Factors associated with increased rate of MRSA acquisition were MRSA prevalence among patients transferred from other wards (rate ratio (RR): 7.74 [95% confidence interval (CI): 3.88, 15.44], additional 5 percentage point), critical care ward (RR: 1.72 [95% CI: 1.09, 2.70]) and presence of MRSA cohorting beds (RR: 1.39 [95% CI: 1.03, 1.90]. Oncology ward (RR: 0.66 [95% CI: 0.46, 0.94]) (compared to medical ward), and median length of stay (RR: 0.70 [95% CI: 0.55, 0.90], additional 1.5 days) were associated with lower acquisition rates. In addition, we found evidence of interaction between MRSA prevalence among patients transferred from other wards and weighted in-degree although the latter was not associated with MRSA acquisition after controlling for confounders.
Conclusion:
Wards with higher MRSA prevalence among patients transferred from other wards were more likely to have higher MRSA acquisition rate. Its effect further increased in wards receiving greater number of patients. In addition, critical care ward, presence of MRSA cohorting beds, ward specialty, and median length of stay were associated with MRSA acquisition.
Insights
Hospital patient transfers increase Methicillin-Resistant Staphylococcus aureus (MRSA) acquisition risk. Higher MRSA prevalence in transferred patients and critical care wards significantly elevate risk, while oncology wards and longer stays reduce it.
Area of Science:
- Infectious Disease Epidemiology
- Hospital-Acquired Infections
- Healthcare Epidemiology
Background:
- Methicillin-Resistant Staphylococcus aureus (MRSA) is a significant global hospital-acquired infection.
- Patient transfers between wards are a potential pathway for MRSA transmission within hospitals.
- Understanding factors influencing MRSA acquisition is crucial for infection control.
Purpose of the Study:
- To investigate the association between ward characteristics, patient transfer networks, and MRSA acquisition rates.
- To identify specific ward features and connectivity patterns that increase or decrease MRSA acquisition risk.
Main Methods:
- Analysis of electronic medical records, including patient transfers and MRSA screening data.
- Retrospective study conducted over four years at an acute-care tertiary hospital.
- Network analysis of in-patient ward connectivity and statistical modeling of MRSA acquisition rates.
Main Results:
- MRSA acquisition rates were significantly higher in wards with greater MRSA prevalence among incoming patients (RR: 7.74) and in critical care units (RR: 1.72).
- The presence of MRSA co-horting beds was associated with increased acquisition (RR: 1.39), while oncology wards (RR: 0.66) and longer median length of stay (RR: 0.70) showed lower rates.
- An interaction was observed between incoming MRSA prevalence and patient inflow, suggesting increased risk in high-traffic wards with prevalent MRSA.
Conclusions:
- Ward-level MRSA prevalence among transferred patients is a primary driver of MRSA acquisition.
- Critical care settings and co-horting strategies require careful management to mitigate MRSA spread.
- Hospital network structure and patient flow dynamics play a role in the epidemiology of MRSA acquisition.
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