Methods: 10,592 GP organisms recovered from blood during the SENTRY Antimicrobial Surveillance Program for USA were included. Isolates were collected from 33 USA sites and were identified by standard biochemical algorithms and MALDI-TOF. Susceptibility (S) testing was performed by CLSI methods.
Results: S. aureus represented 47.1% of isolates recovered from blood during the six-year period, followed by Enterococcus spp. (21.9%; 12.1% and 8.6% of E. faecalis and E. faecium, respectively), coagulase-negative staphylococci (CoNS; 10.5%), beta-hemolytic streptococci (BHS; 8.0%), and viridans group streptococci (VGS; 4.3%). S. aureus rates increased from 46.2 to 52.3% from 2010 to 2012, and decreased to 44.3% in 2015. MRSA rates declined from 45.7% in 2010 to 39.4% in 2014, and increased to 45.4% in 2015. Enterococcus spp. rates decreased during the period (from 25.5% to 18.0%), mostly due to a decline in the E. faecium rates from 10.1% to 6.7%. CoNS prevalence increased from 8.2% to 15.5% over time. ORI had MIC50/90 values of 0.03/0.06 µg/ml against staphylococci, while MIC50/90 results for daptomycin (DAP) and vancomycin (VAN) were 0.25/0.5 µg/ml and 1/1-2 µg/ml, respectively. Only ORI (MIC50/90, 0.015/0.06 µg/ml), DAP (MIC50/90, 1/2 µg/ml), and linezolid (MIC50/90, 1/2 µg/ml) were active against enterococci (32.8% VRE). ORI (MIC50/90, 0.03/0.12 µg/ml; 99.4% S), penicillin (MIC50/90, ≤0.06/≤0.06 µg/ml; 100.0% S), and DAP (MIC50/90, 0.12/0.25 µg/ml; 100.0% S) were the most active agents against BHS, while ORI (MIC50/90, 0.015/0.06 µg/ml; 100.0% S) was the most active agent against VGS.
Conclusion: In this set of bacteremia isolates, S. aureus and MRSA rates remain elevated, while CoNS consolidates as an emergent pathogen. In contrast, rates of enterococcal infections, mainly those due to E. faecium, appear to be declining. ORI had potent in vitro activity against these GP isolates causing invasive infections in USA hospitals.
R. E. Mendes,
The Medicines Company:
M. D. Huband, The Medicines Company: Research Contractor , Research grant
R. K. Flamm, The Medicines Company: Research Contractor , Research grant