Aaron Milstone, MD, highlights persistent risk of Staphylococcus aureus in premature infants

Invasive Staphylococcus aureus infections remain a major cause of illness and death in neonatal intensive care units (NICUs), particularly among very low birth weight (VLBW) infants, according to a study co-authored by Aaron Milstone, MD, MHS, pediatric infectious disease specialist at Johns Hopkins Children’s Center.

"I've been interested in staph infection since I was a fellow,” Milstone explained. “It always amazed me that of all the advances we've had in science, kids in the neonatal intensive care unit (NICU) still die of invasive Staph aureus infections. This is a bacteria we've known about for over 100 years.”

The cohort study, published in JAMA Pediatrics, analyzed data from 468,201 infants hospitalized in 315 NICUs across the United States between 2016 and 2021. Researchers found that late-onset invasive S aureus infections occurred at a rate of 37.6 per 10,000 infants (95% CI, 359.-39.4). Infants with VLBW—those weighing under 1500 grams—represented 12.7% of the study population but accounted for 76.7% of infections and 90.4% of attributable deaths. Infected infants had a 5.3% higher mortality rate than matched infants without infection.

“What really struck me about the study was not just how commonly this is happening in babies, but how commonly it's happening in very low birth weight babies,” Milstone said. “These are our most vulnerable babies."

Milstone noted that about 2% of infants in this weight group developed an invasive Staph aureus infection, more frequent than many other complications seen in NICUs.

“Over 20 years ago, one of the most common causes of infections in babies was a common strep bacteria called Group B strep,” he said. “The incidence at the time was 2 per 1000... and of the kids that got sick, about 5% of them died," said Milstone. “In our current study... 2 per 100 kids are getting this infection, and more than 5% are dying. This bacterial infection in these especially low birth weight babies is 10-times more common than Group B strep was, and the mortality associated with it is similar, if not even higher.”

Milstone emphasized the continued need for targeted infection prevention in NICUs.

"It's a smaller population, because it's not every baby, but it's babies that are born premature and born into the NICU. Their risks of getting this common bacteria and getting infected with it remain high, and it puts them at lots of risks."

Reference:

Jennings MR, Elhaissouni N, Colantuoni E, et al. Epidemiology and Mortality of Invasive Staphylococcus aureus Infections in Hospitalized Infants. JAMA Pediatr. Published online April 14, 2025. doi:10.1001/jamapediatrics.2025.0429