MONTREAL Community-acquired strains are the most common source of methicillin-resistant Staphylococcus aureus colonization and infection in babies in the neonatal intensive care unit, even though they have never left the hospital, researchers found.
Findings in a 5-year retrospective study of 50 MRSA-colonized neonates in the NICU were presented at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology.
"There are higher rates of community-acquired MRSA infection in our neonates than in our general adult and pediatric patient population," said lead investigator Dr. Gweneth Lazenby of the Medical University of South Carolina in Charleston said. "This is a call for people to help us really detail the sources of such early colonization, how we can prevent it, and how we can prevent subsequent infection."
Theories on how neonates are exposed to MRSA in the NICU include maternal transmission, transmission from other family or hospital workers, contaminated equipment, and a recently reported possible transmission through breast milk, she said. "We have some concern about family members and maternal transmission to neonates and so we would like to consider interrupting transmission by possibly culturing the individuals the babies are exposed to."
In the current study, there was a mean of 21 days between birth and colonization of the 50 infants. However, 30% tested positive within 7 days of birth, she said.
"The 30% of infants who acquired early MRSA colonization, within the first week, were 2.5 times more likely to go on to develop infection," she explained. No other risk factors for infection could be identified, although there was a nonsignificant trend toward a higher risk with lower birth weight.
In total, 16 of the 50 colonized infants (32%) eventually developed MRSA infections, which included 8 blood stream infections, 6 skin and soft tissue infections, and 2 ventilator-associated pneumonias. One of the bloodstream infections was fatal and was identified as a community-acquired MRSA strain (USA 300).
Pulse field gel electrophoresis identified USA 300 in 36% of 14 colonizing strains and 56% of 9 infection strains, she said. "This is considerably higher than what is seen in the rest of our hospital's pediatric and adult patient population, where we see a 4%-6% colonization rate and a 19% infection rate, with one-quarter of those infections being community-acquired."
Dr. Lazenby said decolonization is not currently attempted in neonates.
The current management is isolation and contact precautions to prevent spreading the infection, she said.
Dr. Lazenby said she had no disclosures to declare.