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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Genomic Epidemiology of Methicillin-Resistant Staphylococcus aureus in a Neonatal Intensive Care Unit
Taj Azarian1,2, Nizar F Maraqa3,4, Robert L Cook1,2
1College of Public Health and Health Professions and College of Medicine, Department of Epidemiology, University of Florida, Gainesville, FL, United States of America.
Abstract:
Despite infection prevention efforts, neonatal intensive care unit (NICU) patients remain at risk of Methicillin-resistant Staphylococcus aureus (MRSA) infection. Modes of transmission for healthcare-associated (HA) and community-associated (CA) MRSA remain poorly understood and may vary by genotype, hindering the development of effective prevention and control strategies. From 2008-2010, all patients admitted to a level III NICU were screened for MRSA colonization, and all available isolates were spa-typed. Spa-type t008, the most prevalent CA- genotype in the United States, spa-type t045, a HA- related genotype, and a convenience sample of strains isolated from 2003-2011, underwent whole-genome sequencing and phylodynamic analysis. Patient risk factors were compared between colonized and noncolonized infants, and virulence and resistance genes compared between spa-type t008 and non-t008 strains. Epidemiological and genomic data were used to estimate MRSA importations and acquisitions through transmission reconstruction. MRSA colonization was identified in 9.1% (177/1940) of hospitalized infants and associated with low gestational age and birth weight. Among colonized infants, low gestational age was more common among those colonized with t008 strains. Our data suggest that approximately 70% of colonizations were the result of transmission events within the NICU, with the remainder likely to reflect importations of "outside" strains. While risk of transmission within the NICU was not affected by spa-type, patterns of acquisition and importation differed between t008 and t045 strains. Phylodynamic analysis showed the effective population size of spa-type t008 has been exponentially increasing in both community and hospital, with spa-type t008 strains possessed virulence genes not found among t045 strains; t045 strains, in contrast, appeared to be of more recent origin, with a possible hospital source. Our data highlight the importance of both intra-NICU transmission and recurrent introductions in maintenance of MRSA colonization within the NICU environment, as well as spa-type-specific differences in epidemiology.
Insights
Neonatal intensive care unit (NICU) patients face Methicillin-resistant Staphylococcus aureus (MRSA) risks. Both within-NICU transmission and external introductions contribute to MRSA colonization, with distinct genetic patterns influencing spread.
Area of Science:
- Infectious Diseases
- Genomics
- Neonatal Medicine
Background:
- Neonatal intensive care units (NICUs) remain vulnerable to Methicillin-resistant Staphylococcus aureus (MRSA) infections.
- Understanding MRSA transmission modes is crucial for effective prevention and control strategies.
Purpose of the Study:
- To investigate MRSA transmission dynamics and genetic characteristics in a NICU setting.
- To compare risk factors and genomic features between different MRSA spa-types.
Main Methods:
- Screening of NICU patients for MRSA colonization (2008-2010).
- Spa-typing and whole-genome sequencing of MRSA isolates.
- Phylodynamic analysis and comparison of patient risk factors and virulence genes.
Main Results:
- MRSA colonization identified in 9.1% of infants, associated with low gestational age and birth weight.
- Approximately 70% of colonizations resulted from intra-NICU transmission; others were imported.
- Spa-type t008 showed increasing prevalence and unique virulence genes; t045 strains had a potential hospital source.
Conclusions:
- Both intra-NICU transmission and recurrent introductions are key to MRSA colonization in NICUs.
- Spa-type-specific differences in epidemiology, acquisition, and importation patterns were observed.
- Genomic and epidemiological data are vital for targeted MRSA control in vulnerable neonatal populations.
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