[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]
Antimicrobial Activity of Ceftazidime-Avibactam When Tested against Gram-negative Bacteria Isolated from Patients Hospitalized with Pneumonia in United States Medical Centers (2011-2015)
Helio S. Sader⇑, Mariana Castanheira and Robert K. Flamm
Author Affiliations: JMI Laboratories, North Liberty, Iowa, USA
Bacterial isolates were collected from patients hospitalized with pneumonia (PHP), including ventilator-associated (VAP), from 76 USA medical centers in 2011-2015. The Gram-negative organisms (n=11,185; including 1,097 from VAP) were tested for susceptibility against ceftazidime-avibactam and comparators by broth microdilution method. β-lactamase-encoding genes were screened using a microarray based assay on selected isolates. Pseudomonas aeruginosa and Klebsiella spp. were the most common Gram-negatives isolated from PHP and VAP. Ceftazidime-avibactam was very active against P. aeruginosa (n=3,402; MIC50/90, 2/4 μg/mL; 96.6% susceptible), including isolates non-susceptible to meropenem (86.3% susceptible to ceftazidime-avibactam), piperacillin-tazobactam (85.6% susceptible) or ceftazidime (80.6% susceptible). Ceftazidime-avibactam was also highly active against Enterobacteriaceae (MIC50/90, 0.12/0.5 μg/mL; 99.9% susceptible), including carbapenem-resistant (CRE, n=189; MIC50/90, 0.5/2 μg/mL; 98.0% susceptible), multidrug-resistant (MDR; n=674; MIC50/90, 0.25/1 μg/mL; 98.8% susceptible) and extensively drug-resistant Enterobacteriaceae (XDR; n=156; MIC50/90, 0.5/2 μg/mL; 98.1% susceptible) isolates, as well as Klebsiella spp. isolates showing an ESBL screening-positive phenotype (n=433; MIC50/90, 0.25/1 μg/mL; 99.5% susceptible). Among Enterobacter spp. (24.8% ceftazidime-non-susceptible), 99.8% of isolates, including 99.4% of ceftazidime-non-susceptible isolates, were susceptible to ceftazidime-avibactam. The most common β-lactamases detected among K. pneumoniae and E. coli were KPC-like and CTX-M-15, respectively. Only eight of 6,209 Enterobacteriaceae isolates (0.1%) were ceftazidime-avibactam-non-susceptible, three NDM-1 producing strains with ceftazidime-avibactam MIC values of >32 μg/mL and five isolates with ceftazidime-avibactam MIC values of 16 μg/mL and negative results for all β-lactamases tested. Susceptibility rates among isolates from VAP were generally similar or slightly higher compared to those from all PHP.
Contact Information: Helio S. Sader, MD, PhD, JMI Laboratories, 345 Beaver Kreek Ctr, Ste A, North Liberty, Iowa, 52317, USA, Phone: 319-665-3370, Fax: 319-665-3371, firstname.lastname@example.org
Copyright © 2017 American Society for Microbiology.
Keywords: Pneumonia; Antibiotics; Drugs Resistance; Avibactam.