259. Antimicrobial Activity of Ceftaroline Tested Against Bacteria Collected from Patients with Respiratory Tract Infections in the United States (2010)
Session: Poster Abstract Session: Antimicrobial Susceptibility and Resistance
Friday, October 21, 2011
Room: Poster Hall B1

Background: Ceftaroline (CPT), the active form of CPT fosamil, is a broad-spectrum cephalosporin with bactericidal activity against Gram-positive pathogens causing respiratory tract infections (RTI), including MRSA, penicillin (PEN)-resistant (R) S. pneumoniae (SPN), and common Gram-negative organisms. CPT fosamil is USA-FDA-approved for the treatment of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections.

Methods: Isolates were consecutively collected in 62 United States (USA) medical centers from patients with RTI in 2010. CPT and comparator antimicrobials used to treat RTI were evaluated by CLSI broth microdilution methods. A total of 2,263 strains were tested, including 863 SPN (23.8% PEN-R [MIC, ≥2 mg/mL]; 10.8% ceftriaxone[CRO]-non-susceptible [S]), 670 H. influenzae (HI; 27.9% β-lactamase[BL]-producers), 190 S. aureus (47.8% MRSA), 178 M. catarrhalis (MC), 110 β-haemolytic streptococci (BHS), 178 enteric bacilli (EB), 40 viridans group streptococci and 34 H. parainfluenzae.

Results: Against PEN-R SPN, CPT (MIC50/90, 0.12/0.25 μg/mL; highest MIC, 0.5 mg/mL) was 8- to 32-fold more active than CRO (MIC50/90, 1/2 μg/mL; 55.1% S), amoxicillin/clavulanate (MIC50/90, 8/8 μg/mL; 20.5% S) and cefuroxime (MIC50/90, 8/16 μg/mL; 0.0% S). CPT was also very active against CRO-non-S SPN (MIC50/90, 0.25/0.5 μg/mL). The highest CPT MIC among HI was 0.25 μg/mL (1 isolate) and activity against HI was not adversely affected by BL production. CPT was very active against MRSA (MIC50/90, 0.5/1 μg/mL) and 16-fold more active than CRO (MIC50/90, 4/4 μg/mL) when tested against MSSA. MC (MIC50/90, 0.06/0.12 μg/mL), BHS (MIC50/90, ≤0.008/0.015 μg/mL) and VGS (MIC50/90, 0.03/0.5 μg/mL) were also very S to CPT. Non-ESBL-producing EB were CPT-S while ESBL-phenotype EB exhibited decreased S to CPT and all cephalosporins tested.

Conclusion: CPT exhibited potent activity against pathogens recently collected from RTI patients in USA centers, including multidrug-R SPN and MRSA. Based on these results, CPT appears to be a valuable agent for contemporary treatment of RTI.


Subject Category: A. Antimicrobial agents and Resistance

Helio S. Sader, M.D., Ph.D., David J. Farrell, Ph.D. and Ronald Jones, MD, Microbiology, JMI Laboratories, North Liberty, IA

Disclosures:

H. S. Sader, None

D. J. Farrell, None

R. Jones, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.