MSSA infections surpass MRSA, match mortality risk among infants

MEMPHIS, Tenn. — While mortality remained higher for infants with methicillin-resistant Staphylococcus aureus infections, there were more invasive methicillin-sensitive S. aureus infections and a greater absolute number of deaths after this infection, according to data presented at the St. Jude/PIDS Pediatric Infectious Diseases Research Conference.

To assess the burden of S. aureus disease among hospitalized infants, Jessica E. Ericson, MD, from the department of pediatrics at Duke University Medical Center, and colleagues identified infants aged younger than 120 days (n = 887,910) who had presented with a positive S. aureus culture and were discharged from 260 neonatal intensive care units between 1997 and 2012.

Jessica E. Ericson

The researchers defined cultures collected from cerebrospinal fluid, blood, sterile fluid or an abscess to be invasive infections and those from the conjunctiva, trachea, urine or wounds to be noninvasive infections.

Ericson and colleagues then compared demographics and mortality of infants with invasive MRSA and MSSA to determine the annual proportion of S. aureus cultures that were MRSA.

Among the infants surveyed, 1% (n = 9,999) exhibited 11,950 episodes of S. aureus infection, with MSSA infections (71%) significantly more common than MRSA infections (29%).

Ericson and colleagues wrote that infants with invasive MRSA or MSSA infections demonstrated similar gestational ages and birth weights, but invasive MRSA infections occurred at a younger median postnatal age.

In addition, unadjusted mortality was observed to be greater for infants whose last invasive infection was MRSA (12%) compared with MSSA (10%) (P = .049).

“In terms of risk factors, there was no significant difference between infants who got MSSA and those who had MRSA invasive infection; they had the same amount of prior surgical procedures, time on antibiotics and gestational age,” Ericson told Infectious Diseases in Children. “When we looked at outcomes, we found that MSSA occurs in three times as many infants as MRSA and yet the risk of death is the same.”

Based on these results, Ericson and colleagues noted that consideration should be given to expanding hospital infection-control efforts targeting MRSA to also include MSSA.

Reference:

Ericson Jessica E. Abstract R201526. Presented at: St. Jude/PIDS Pediatric Infectious Diseases Research Conference; Feb. 20-21, 2015; Memphis, Tennessee.

Disclosure: Ericson reported no relevant financial disclosures.