Background: MRSA has been increasingly identified as a cause of community-onset infections. Although the initial community-acquired (CA)-MRSA strains were more susceptible (S) to antimicrobial agents compared to traditional hospital-acquired (HA)-MRSA strains, CA-MRSA variants with multidrug resistance patterns have been increasingly reported.
Methods : Among 8,437 MRSA strains collected through the ceftaroline (CPT) AWARE program (2012-2014), 7,116 and 1,321 were reported as CA- and HA-MRSA, respectively. Organisms were collected from 145 medical centers in the USA and tested for S against CPT and comparators by the broth microdilution method.
Results: CA-/HA-MRSA were isolated mainly from patients with skin and skin structure infections (SSSI; 68.4/27.0%), pneumonia (13.7/49.0%) and bacteremia (10.0/17.7%). Overall, S rates were generally lower among HA-MRSA compared to CA-MSA strains (Table), especially for clindamycin (CLI; 61.4 vs. 76.6%) and levofloxacin (LEV; 21.4 vs. 35.5%). CPT was active against 98.0% of CA-MRSA and 94.3% of HA-MRSA (MIC50/90, 1 μg/mL for both) overall, with little variation among infection type subsets. Among SSSI and bacteremia isolates, S rates for CLI and LEV were lower among HA-MRSA compared to CA-MRSA. Further, S rates among isolates from pneumonia were generally lower compared to isolates from SSSI and bacteremia. Tetracycline (TET) and trimethoprim/sulfamethoxazole (T/S) exhibited good in vitro activity against CA- and HA-MRSA from all infection types. Erythromycin (ERY) S was generally low.
Conclusion: CPT exhibited potent in vitro activity against CA- and HA-MRSA isolates independent of infection type. S rates were generally lower among HA-MRSA and varied according to the type of infection.
H. S. Sader,
R. E. Mendes, Actavis: Research Contractor , Research support
R. K. Flamm, Actavis: Research Contractor , Research support
R. N. Jones, Actavis: Research Contractor , Research support