In Vitro Activity of Ceftaroline against Gram-Positive and Gram-Negative Pathogens Isolated from Patients in Canadian Hospitals in 2009

Abstract

ABSTRACTThein vitroactivities of ceftaroline and comparative agents were determined for a collection of the most frequently isolated bacterial pathogens from hospital-associated patients across Canada in 2009 as part of the ongoing CANWARD surveillance study. In total, 4,546 isolates from 15 sentinel Canadian hospital laboratories were tested using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Compared with other cephalosporins, including ceftobiprole, cefepime, and ceftriaxone, ceftaroline exhibited the greatest potency against methicillin-susceptibleStaphylococcus aureus(MSSA), with a MIC90of 0.25 μg/ml. Ceftaroline also demonstrated greater potency than ceftobiprole against community-associated methicillin-resistantS. aureus(MRSA) (MIC90, 0.5 μg/ml) and health care-associated MRSA (MIC90, 1 μg/ml) and was at least 4-fold more active than other cephalosporins againstStaphylococcus epidermidis; all isolates of MSSA and MRSA tested were susceptible to ceftaroline (MIC, ≤1 μg/ml). Against streptococci, includingStreptococcus pneumoniae, ceftaroline MICs (MIC90, ≤0.03 μg/ml) were comparable to those of ceftobiprole; however, against penicillin-nonsusceptible, macrolide-nonsusceptible, and multidrug-nonsusceptible isolates ofS. pneumoniae, ceftaroline demonstrated 2- to 4-fold and 4- to 16-fold more potent activities than those of ceftobiprole and ceftriaxone, respectively. All isolates ofS. pneumoniaetested were susceptible to ceftaroline (MIC, ≤0.25 μg/ml). Among Gram-negative isolates, ceftaroline demonstrated potent activity (MIC90, ≤0.5 μg/ml) againstEscherichia coli(92.2% of isolates were susceptible),Klebsiella pneumoniae(94.1% of isolates were susceptible),Proteus mirabilis(97.7% of isolates were susceptible), andHaemophilus influenzae(100% of isolates were susceptible). Ceftaroline demonstrated less potent activity (MIC90, ≥4 μg/ml) againstEnterobacterspp.,Acinetobacter baumannii,Pseudomonas aeruginosa,Klebsiella oxytoca,Serratia marcescens, andStenotrophomonas maltophilia. Overall, ceftaroline demonstrated potentin vitroactivity against a recent collection of the most frequently encountered Gram-positive and Gram-negative isolates from patients attending hospitals across Canada in 2009.