Program Schedule

Genomic Epidemiology of Methicillin-resistant Staphylococcus aureus in a Neonatal Intensive Care Unit

Session: Poster Abstract Session: MRSA and VRE
Thursday, October 9, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of healthcare-associated infections (HAI). The prevalence of community-associated (CA) MRSA strains has increased in hospitals. We previously demonstrated that spa-type t008 CA-MRSA strains have been replacing spa-type t002 and t045 healthcare-associated (HA) MRSA strains among colonized infants in our Neonatal Intensive Care Unit (NICU). However, spa-typing lacks the discriminatory resolution to determine the cause of this epidemiological shift. Whole genome sequencing (WGS) and phylogenetic analysis may better characterize MRSA transmission in the NICU.

Methods: Since 2004, we have performed admission and weekly MRSA screening of all infants admitted to the level III NICU in Jacksonville, FL (AJIC 2011;39:35-41). Isolates from infants (n=411) were spa-typed to characterize prevalent strains within the NICU.  Strains identified as spa­-type t008 (n=55), representing the prevalent CA-MRSA lineage, and spa­-type t045 (n=41), representing the prevalent HA-MRSA lineage, underwent WGS and phylogenetic analysis to understand the putative replacement of HA- strains and to assess the endemnicity of CA strains within the unit. Infant demographic and clinical data were extracted electronically.

Results: A total of 5,212 infants were admitted to the NICU during the study period (2004-2011) representing 128,422 patient days (pd). The colonization prevalence among infants was 3.62 per 1000 pd. Preliminary epidemiological and phylogenetic analysis of spa-type t008 and t045 strains demonstrated a complex dynamic marked by both multiple introductions of t008 strains and putative nosocomial transmission as suggested by different individuals having nearly identical MRSA WGS.

Conclusion: Our findings show evidence of multiple introductions of MRSA into the NICU, possibly due to increasing community-wide prevalence resulting in greater colonization pressure from patients, staff, and visitors. Given that spa-typing alone cannot distinguish introductions from the community vs. nosocomial transmission (i.e. sporadic vs. epidemic cases), WGS should be used as the gold standard to investigate the emergence and transmission of MRSA and to inform evidence-based, targeted control measures.

Taj Azarian, MPH, PhDc1, Nizar Maraqa, MD2, Mobeen Rathore, MD3, Christine Bailey, BSN, MSH4, Diane Halstead, PhD5, Robert Cook, MD1, Judith Johnson, PhD6, J Glenn Morris, MD, MPH, TM7 and Marco Salemi, PhD8, (1)Epidemiology, University of Florida, Gainesville, FL, (2)Pediatric Infectious Diseases and Immunology, University of Florida College of Medicine- Jacksonville, Jacksonville, FL, (3)University of Florida Center for HIV/AIDS Research, Education and Service (UF CARES)- Jacksonville, Jacksonville, FL, (4)Epidemiology and Infection Control, Wolfson Children's Hospital, Jacksonville, FL, (5)Baptist Health, Jacksonville, FL, (6)Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, (7)Emerging Pathogens Institute, University of Florida, Gainesville, FL, (8)Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL


T. Azarian, None

N. Maraqa, None

M. Rathore, None

C. Bailey, None

D. Halstead, None

R. Cook, None

J. Johnson, None

J. G. Morris, None

M. Salemi, None

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