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Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
Published on: September 5, 2013
Transmission Clusters of Methicillin-Resistant Staphylococcus Aureus in Long-Term Care Facilities Based on
O Colin Stine1, Shana Burrowes1, Sophia David2
11Department of Epidemiology and Public Health,University of Maryland School of Medicine,Baltimore,Maryland,United States.
Abstract:
OBJECTIVE To define how often methicillin-resistant Staphylococcus aureus (MRSA) is spread from resident to resident in long-term care facilities using whole-genome sequencing DESIGN Prospective cohort study SETTING A long-term care facility PARTICIPANTS Elderly residents in a long-term care facility METHODS Cultures for MRSA were obtained weekly from multiple body sites from residents with known MRSA colonization over 12-week study periods. Simultaneously, cultures to detect MRSA acquisition were obtained weekly from 2 body sites in residents without known MRSA colonization. During the first 12-week cycle on a single unit, we sequenced 8 MRSA isolates per swab for 2 body sites from each of 6 residents. During the second 12-week cycle, we sequenced 30 MRSA isolates from 13 residents with known MRSA colonization and 3 residents who had acquired MRSA colonization. RESULTS MRSA isolates from the same swab showed little genetic variation between isolates with the exception of isolates from wounds. The genetic variation of isolates between body sites on an individual was greater than that within a single body site with the exception of 1 sample, which had 2 unrelated strains among the 8 isolates. In the second cycle, 10 of 16 residents colonized with MRSA (63%) shared 1 of 3 closely related strains. Of the 3 residents with newly acquired MRSA, 2 residents harbored isolates that were members of these clusters. CONCLUSIONS Point prevalence surveys with whole-genome sequencing of MRSA isolates may detect resident-to-resident transmission more accurately than routine surveillance cultures for MRSA in long-term care facilities. Infect Control Hosp Epidemiol 2016;37:685-691.
Insights
Whole-genome sequencing revealed that methicillin-resistant Staphylococcus aureus (MRSA) transmission is common in long-term care facilities, with 63% of colonized residents sharing closely related strains. This method offers more accurate detection of MRSA spread than standard surveillance cultures.
Area of Science:
- Infectious Disease Epidemiology
- Genomic Epidemiology
- Healthcare-Associated Infections
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in long-term care facilities (LTCFs).
- Understanding resident-to-resident transmission dynamics is crucial for effective infection control.
- Traditional surveillance methods may not fully capture the extent of MRSA spread.
Purpose of the Study:
- To quantify the frequency of methicillin-resistant Staphylococcus aureus (MRSA) spread among residents in a long-term care facility.
- To evaluate the utility of whole-genome sequencing (WGS) in tracking MRSA transmission events.
- To compare WGS-based detection with routine surveillance cultures for MRSA.
Main Methods:
- Prospective cohort study conducted in a long-term care facility over two 12-week cycles.
- Weekly MRSA cultures from multiple body sites of colonized and non-colonized residents.
- Whole-genome sequencing of selected MRSA isolates to analyze genetic relatedness and transmission patterns.
Main Results:
- MRSA isolates from the same body site generally showed low genetic variation, except from wound sites.
- Higher genetic variation was observed between body sites of an individual compared to within a single body site.
- During the second cycle, 63% of colonized residents (10/16) shared closely related MRSA strains, with 2/3 newly colonized residents acquiring these strains.
Conclusions:
- Point prevalence surveys combined with whole-genome sequencing can more accurately identify resident-to-resident MRSA transmission in LTCFs.
- WGS provides a higher resolution for detecting transmission events compared to routine surveillance cultures.
- Findings highlight the potential for widespread dissemination of specific MRSA strains within LTCF settings.
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