[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Antimicrobial activity of ceftolozane/tazobactam tested against Enterobacteriaceae and Pseudomonas aeruginosa with various resistance patterns isolated in U.S. hospitals (2011-2012)

David J. Farrell 1,2*, Robert K. Flamm 1, Helio S. Sader 1,3 and Ronald N. Jones 1,4

Author Affiliations: <SUP>1</SUP>JMI Laboratories, North Liberty, Iowa 52317 USA <SUP>2</SUP>Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada <SUP>3</SUP>Division of Infectious Diseases, Federal University of S?o Paulo, S?o Paulo, SP, Brazil <SUP>4</SUP>Tufts University School of Medicine, Boston, Massachusetts 02111 USA.


Ceftolozane/tazobactam, a novel antimicrobial agent with activity against Pseudomonas aeruginosa (including drug-resistant strains) and other common Gram-negative pathogens (including most extended-spectrum β-lactamase [ESBL]-producing Enterobacteriaceae) and comparator agents were susceptibility tested by a reference broth microdilution method against 7,071 Enterobacteriaceae and 1,971 P. aeruginosa. Isolates were collected consecutively from patients in 32 medical centers across the United States (U.S.) during 2011 to 2012. Overall, 15.7/8.9% of P. aeruginosa were classified as multidrug-resistant (MDR)/extensively drug-resistant (XDR), and 8.4/1.2% of Enterobacteriaceae were classified as MDR/XDR. No pandrug-resistant (PDR) Enterobacteriaceae and only one PDR P. aeruginosa were detected. Ceftolozane/tazobactam was the most potent (MIC<SUB>50/90</SUB>, 0.5/2 μg/ml) agent tested against P. aeruginosa and demonstrated good activity against 310 MDR strains (MIC<SUB>50/90</SUB>, 2/8 μg/ml) and 175 XDR strains (MIC<SUB>50/90</SUB>, 4/16 μg/ml). Ceftolozane/tazobactam exhibited high overall activity (MIC<SUB>50/90</SUB>, 0.25/1 μg/ml) against Enterobacteriaceae and retained activity (MIC<SUB>50/90</SUB>, 4/>32 μg/ml) against many 601 MDR strains, but not against the 86 XDR strains (MIC<SUB>50</SUB>, >32 μg/ml). Ceftolozane/tazobactam was highly potent (MIC<SUB>50/90</SUB>, 0.25/0.5 μg/ml) against 2,691 E. coli isolates and retained good activity against most ESBL-phenotype Escherichia coli (MIC<SUB>50/90</SUB>, 0.5/4 μg/ml), but activity was low against ESBL-phenotype Klebsiella pneumoniae (MIC<SUB>50/90</SUB>, 32/>32 μg/ml), explained by the high rate (39.8%) of meropenem co-resistance observed in this species phenotype. In summary, ceftolozane/tazobactam demonstrated high potency and broad-spectrum activity against many contemporary Enterobacteriaceae and P. aeruginosa isolated in U.S. medical centers. Importantly, ceftolozane/tazobactam retained potency against many MDR and XDR strains.


*Corresponding author: David J. Farrell, Ph.D., D(ABMM), JMI Laboratories, 345 Beaver Kreek Centre, Suite A, North Liberty, Iowa 52317, Phone: (319) 665-3370, Fax: (319) 665-3371, david-farrell@jmilabs.com

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