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Updated: May 12, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
Published on: February 9, 2011
Do active surveillance and contact precautions reduce MRSA acquisition? A prospective interrupted time series
Caroline Marshall1, Michael Richards, Emma McBryde
1Victorian Infectious Diseases Service, Royal Melbourne Hospital and Department of Medicine, University of Melbourne, Parkville, Victoria, Australia. caroline.marshall@mh.org.au
Background:
Consensus for methicillin-resistant Staphylococcus aureus (MRSA) control has still not been reached. We hypothesised that use of rapid MRSA detection followed by contact precautions and single room isolation would reduce MRSA acquisition.
Methods:
This study was a pre-planned prospective interrupted time series comparing rapid PCR detection and use of long sleeved gowns and gloves (contact precautions) plus single room isolation or cohorting of MRSA colonised patients with a control group. The study took place in a medical-surgical intensive care unit of a tertiary adult hospital between May 21(st) 2007 and September 21(st) 2009. The primary outcome was the rate of MRSA acquisition. A segmented regression analysis was performed to determine the trend in MRSA acquisition rates before and after the intervention.
Findings:
The rate of MRSA acquisition was 18.5 per 1000 at risk patient days in the control phase and 7.9 per 1000 at-risk patient days in the intervention phase, with an adjusted hazard ratio 0.39 (95% CI 0.24 to 0.62). Segmented regression analysis showed a decline in MRSA acquisition of 7% per month in the intervention phase, (95%CI 1.9% to 12.8% reduction) which was a significant change in slope compared with the control phase. Secondary analysis found prior exposure to anaerobically active antibiotics and colonization pressure were associated with increased acquisition risk.
Conclusion:
Contact precautions with single room isolation or cohorting were associated with a 60% reduction in MRSA acquisition. While this study was a quasi-experimental design, many measures were taken to strengthen the study, such as accounting for differences in colonisation pressure, hand hygiene compliance and individual risk factors across the groups, and confining the study to one centre to reduce variation in transmission. Use of two research nurses may limit its generalisability to units in which this level of support is available.
Insights
Rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) combined with contact precautions and isolation significantly reduced MRSA acquisition by 60%. This intervention proved effective in a medical-surgical intensive care unit, highlighting its potential for infection control.
Area of Science:
- Infectious Diseases
- Hospital Epidemiology
- Microbiology
Background:
- Consensus on methicillin-resistant Staphylococcus aureus (MRSA) control remains elusive.
- A hypothesis proposed that rapid MRSA detection coupled with contact precautions and single room isolation would decrease MRSA acquisition.
- This approach aims to mitigate the spread of this resistant pathogen in healthcare settings.
Purpose of the Study:
- To evaluate the effectiveness of rapid MRSA detection followed by contact precautions and isolation in reducing MRSA acquisition.
- To compare MRSA acquisition rates in an intervention group versus a control group within a tertiary adult hospital's medical-surgical intensive care unit.
- To analyze trends in MRSA acquisition rates before and after the implementation of the intervention using segmented regression analysis.
Main Methods:
- A prospective interrupted time series design was employed, comparing rapid PCR detection, contact precautions (gowns/gloves), and single room isolation/cohorting against a control group.
- The study was conducted in a medical-surgical ICU from May 2007 to September 2009.
- MRSA acquisition rate was the primary outcome, analyzed via segmented regression to assess trend changes.
Main Results:
- MRSA acquisition rates decreased from 18.5 to 7.9 per 1000 patient days (adjusted hazard ratio 0.39).
- Segmented regression revealed a significant monthly decline of 7% in MRSA acquisition during the intervention phase.
- Antibiotic exposure and colonization pressure were identified as factors increasing MRSA acquisition risk.
Conclusions:
- Contact precautions with isolation strategies led to a 60% reduction in MRSA acquisition.
- The study employed rigorous methods to strengthen findings, including controlling for colonization pressure and risk factors.
- Generalizability may be limited by the intensive support, such as dedicated research nurses, required for the intervention.
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