Invasive Antibiotic Sensitive Infections Are Widespread In Hospitalized Infants

Staphylococcus aureus is a frequent cause of infection in hospitalized infants and infections due to S. aureus are associated with increased mortality, morbidity, and length of hospital stay. S. aureus is the second most frequent cause of late-onset sepsis in very low-birth-weight (VLBW) infants less than 1,500 grams.

Invasive methicillin-susceptible Staphylococcus aureus infection (MSSA) caused more infections and more deaths in hospitalized infants than invasive methicillin-resistant S. aureus infection (MRSA), which suggests measures to prevent S.aureus infections should include MSSA in addition to MRSA.

Scientists at Duke University School of Medicine (Durham, NC, USA) compared demographics and mortality of infants with MRSA and MSSA at 348 neonatal intensive care units (NICUs) around the USA to determine the annual proportion of S. aureus infections that were MRSA and to contrast the risk of death after invasive MRSA and MSSA infections. Participants were infants with an invasive S. aureus infection who were discharged from calendar year 1997 through calendar year 2012.

The authors identified 3,888 of 887,910 infants (0.4%) with 3,978 invasive S. aureus infections. Infections were more commonly caused by MSSA, 2,868 of 3,978 (72.1%) than MRSA (1,110 of 3,978 (27.9%). Overall, invasive S. aureus infections had an incidence of 44.8 infections per 10,000 infants, according to the results. The annual incidence of invasive S. aureus infection increased from 1997 through 2006 and then declined modestly from 2007 through 2012. The study indicates invasive S. aureus infections were more common in infants born at less than 1,500 grams (3,061 of 136,797 or 223.8 per 10,000 infants) than in infants born at 1,500 grams or higher (915 of 748,715 or 12.2 per 10,000 infants).

There were 237 infants with invasive MSSA infections who died before hospital discharge compared to 110 infants with invasive MRSA infections. However, the proportions of infants who died after invasive MSSA and MRSA infections were similar at 237/2,474 (9.6%) and 110/926 (11.9%). The adjusted risk of death before hospital discharge and the risk of death at 7 and 30 days after invasive infection were similar between infants with invasive MSSA infection and invasive MRSA infection, the results indicate.

The authors concluded that the absolute numbers of infections and deaths due to MSSA exceed those due to MRSA. Consideration should be given to expanding hospital infection control efforts targeting MRSA to include MSSA as well. Future studies to better define the relationship between MSSA colonization and subsequent infection will help to clarify the importance of such interventions for preventing MSSA disease. The study was published on October 19, 2015, in the journal JAMA Pediatrics.

Related Links:
Duke University School of Medicine