(HealthDay News) — Invasive methicillin-susceptible Staphylococcus aureus (MSSA) infections are more common than invasive methicillin-resistant Staphylococcus aureus (MRSA) infections, according to a study published online October 19 in JAMA Pediatrics.

Jessica E. Ericson, MD, from the Duke University School of Medicine in Durham, NC, and colleagues compared the demographics and mortality for infants with invasive MRSA and MSSA. The authors used data from a large, nationally representative cohort of patients who were treated at 348 neonatal intensive care units managed by the Pediatrix Medical Group. Participants (3,888 infants) were discharged (1997–2012) with an invasive S. aureus infection.

The researchers noted 2,868 MSSA and 1,110 MRSA infections, with an incidence of invasive S. aureus infection of 44.8 infections per 10,000 infants. The proportion of MRSA infections increased from calendar year 1997–2006, but has moderately decreased since then. Gestational ages and birth weights were similar regardless of invasive MRSA or MSSA infections, although invasive MRSA infections occurred more often at a younger postnatal age. Death before hospital discharge was more frequent among infants with invasive MSSA infections (237), compared to infants with invasive MRSA infections (110), although the proportions of infants who died after invasive MSSA and MRSA infections were similar (9.6 and 11.9%, respectively; P=0.05).

“Infant mortality after invasive MRSA and MSSA infections is similar, but MSSA causes more infections and more deaths in infants than MRSA,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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