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. E. Acree,
M. Z. David, None