1116. Comparing the Incidence of MSSA and MRSA Infections in Children and Adults at an Academic Medical Center, 2006-13
Session: Poster Abstract Session: MRSA/VRE Epidemiology
Friday, October 9, 2015
Room: Poster Hall

The incidence of MRSA and MSSA infections in children and adults at a medical center have rarely been compared.


From a data warehouse at the University of Chicago, inpatient (IP), outpatient and emergency department (ED) patient encounters (PE) in 2006-13 were identified in which S. aureus (SA) was cultured. Only the first PE per year was included for each patient. A syndrome was assigned to each infection using ICD9 codes and site of culture. Each was classified as community-associated (CA) or healthcare-associated (HA).


Among 10,270 SA infections, 1517 were in 2006 (1.853 per 1000 PE) and 1301 (1.521) in 2013. 42.4% of pediatric and 53.9% of adult SA infections were MRSA. 74.2% of pediatric and 48.8% of adult MRSA infections were CA. In 2006-13 the incidence of SA infections decreased in children (5.117 per 1000 PE to 2.941) and adults (1.337 to 1.285) (P <0.001). MRSA incidence decreased from 1.033 per 1000 PE in 2006 to 0.655 in 2013, on average -7.5% per year. MSSA incidence did not significantly change.  

Of 5567 MRSA infections, 59% were skin and soft tissue infections (SSTIs); 7.1% were unclassified. 86.6% of pediatric SSTIs were in the ED vs. 51.2% of adult SSTIs. In 2006-13, the incidence of all SA SSTIs for both adults and children did not significantly change (P = 0.2). In 2006-13, pediatric CA-MRSA SSTIs decreased by 11.4% on average per year (P <0.001) and HA-MRSA SSTIs, by 6.6% (P=0.01). In 2006-13 adult MRSA SSTI incidence increased from 0.221 per 1000 PE to 0.307. Adult CA-MRSA SSTIs decreased by 10% on average per year (P <0.001), but HA-MRSA SSTIs did not change significantly (P=0.6).

22.2% of MRSA infections were invasive. The incidence of IP pediatric invasive infection incidence decreased from 0.268 per 1000 IP PE in 2006 to 0.107 in 2013. In 2006-13, pediatric CA-MRSA invasive infection incidence decreased by 10.3% on average per year (P=0.009) and HA-MRSA invasive infection incidence, by 11.1% (P=0.001). Adult IP MRSA invasive infection incidence decreased from 0.322 per 1000 IP PE in 2006 to 0.164 in 2013. Adult CA-MRSA invasive infection incidence decreased by 12.3% on average per year (P <0.001) and HA-MRSA invasive infections, by 5.7% (P <0.001).


In 2006-13, the incidence of pediatric HA and CA-MRSA SSTIs decreased. The incidence of adult CA-MRSA SSTIs decreased. Adult and pediatric HA and CA-MRSA invasive infection incidence decreased significantly.

M. Ellen Acree, MD1, Ethan Morgan, BS2 and Michael Z David, MD PhD1, (1)Section of Infectious Diseases and Global Health, Dept of Medicine, University of Chicago Medicine, Chicago, IL, (2)Dept of Public Health Sciences, University of Chicago, Chicago, IL


M. E. Acree, None

E. Morgan, None

M. Z. David, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.