Decreased ceftriaxone susceptibility in emerging (35B and 6C) and persisting (19A) Streptococcus pneumoniae serotypes in the United States, 2011-2012: Ceftaroline remains active in vitro among β-lactam agents

Abstract

Totals of 8.7% (103/1,190) and 21.0% (249/1,190) of the Streptococcus pneumoniae isolates recovered from specimens collected in the United States during the 2011-2012 AWARE (Assessing Worldwide Antimicrobial Resistance Evaluation) Surveillance Program were ceftriaxone nonsusceptible according to the CLSI (≤1 μg/ml for susceptible) and EUCAST (≤0.5 μg/ml for susceptible) criteria, respectively. Decreased susceptibility to ceftriaxone (MIC, 1 μg/ml) was frequently observed among serotypes 19A (51.4%; 128/249) and 35B (29.7%; 74/249), which were most often observed in the East South Central and South Atlantic U.S. Census regions. Ceftaroline (MIC 50/90, 0.12/0.25 μg/ml) remained active (≥96.8% susceptible) when tested against these less susceptible isolates. Copyright © 2014, American Society for Microbiology. All Rights Reserved.