Antimicrobial Activity of Ceftaroline Tested Against Streptococci from United States (USA) and European (EU) Medical Centers: Results from the Ceftaroline Surveillance Program

Results: Penicillin (PEN) S (≤0.06/≤2 µg/mL) among S. pneumoniae (SPN) were 58/87% in the USA and 73/92% in EU. CPT (MIC 90 /highest MIC, 0.12/0.5 μg/mL) was 8-fold more potent than ceftriaxone (CRO; MIC 90 , 1 μg/mL; 91% S) and 32- to 64-fold more potent than cefuroxime (FUR; MIC 90 , 4-8 µg/mL; 70-80% S). SPN S to amoxicillin/clavulanate (A/C), azithromycin, trimethoprim/ sulfamethoxazole and levofloxacin (LEV) were (USA/EU): 83/93, 59/66, 66/71 and 99/97%, respectively. Against β-haemolytic streptococci (βHS), CPT was 2- to 4-fold more potent than PEN (MIC 90 , 0.06 µg/mL) and 32- to ≥128-fold more potent than linezolid or LEV (MIC 90 , 1 µg/mL for both). All βHS strains were inhibited at ≤0.06 µg/mL of CPT and LEV R was observed in 4 βHS from the USA. CPT was also very active against viridans gr. streptococci (VGS; MIC 90 , 0.12 µg/mL) and all isolates except 1 were inhibited at ≤1 µg/mL of CPT. S to PEN, CRO and LEV among VGS were (USA/EU): 72/78, 90/92 and 86/89%, respectively. • The highest ceftaroline MIC values observed among penicillin- susceptible (MIC, ≤0.06 µg/mL), penicillin-intermediate (MIC, 0.12 - 1 µg/mL), and penicillin-resistant (MIC, ≥2 µg/mL) strains of S. pneumoniae were 0.06, 0.25, and 0.5 µg/mL, respectively (Table 3); while the MIC 50 varied from ≤0.008 µg/mL for the penicillin- susceptible to 0.12 µg/mL for the penicillin-resistant strains (Tables 1 and 2). • As with other β-lactams, the in vitro activity of ceftaroline increased with increasing susceptibility to penicillin. Ceftaroline