Neonatal MRSA Often Community Acquired


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 have 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,” lead investigator Dr. Gweneth Lazenby of the Medical University of South Carolina in Charleston said in an interview. “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 members 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—including health care workers.”

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—including ethnicity, sex, method of delivery, gestational age, or length of stay—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 eight blood stream infections, six skin and soft tissue infections, and two ventilator-associated pneumonia cases.

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. “No one has looked at the effect of topical decolonization, and we do try to be as minimally invasive as possible with neonates in the NICU.”

The current management of colonized infants is isolation and contact precautions to prevent spreading the infection to other babies, she said.

Disclosures: None was reported.

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