Pharmacodynamics of β-lactamase inhibition by NXL104 in combination with ceftaroline: examining organisms with multiple types of β-lactamases.
New broad-spectrum β-lactamases such as KPC enzymes and CTX-M-15 enzymes threaten to markedly reduce the utility of our armamentarium of β-lactam agents, even our most potent drugs, such as carbapenems. NXL104 is a broad-spectrum non-β-lactam β-lactamase inhibitor. In this evaluation, we examined organisms carrying defined β-lactamases and identified doses and schedules of NXL104 in combination with the new cephalosporin ceftaroline, which would maintain good bacterial cell kill and suppress resistance emergence for a clinically relevant period of 10 days in our hollow-fiber infection model. We examined three strains of Klebsiella pneumoniae and one isolate of Enterobacter cloacae. K. pneumoniae 27-908M carried KPC-2, SHV-27, and TEM-1 β-lactamases. Its isogenic mutant, K. pneumoniae 4207J, was "cured" of the plasmid expressing the KPC-2 enzyme. K. pneumoniae 24-1318A carried a CTX-M-15 enzyme, and E. cloacae 2-77C expressed a stably derepressed AmpC chromosomal β-lactamase. Dose-ranging experiments for NXL104 administered as a continuous infusion with ceftaroline at 600 mg every 8 h allowed identification of a 24-h area under the concentration-time curve (AUC) for NXL104 that mediated bactericidal activity and resistance suppression. Dose fractionation experiments identified that "time > threshold" was the pharmacodynamic index linked to cell kill and resistance suppression. Given these results, we conclude that NXL104 combined with ceftaroline on an 8-hourly administration schedule would be optimal for circumstances in which highly resistant pathogens are likely to be encountered. This combination dosing regimen should allow for optimal bacterial cell kill (highest likelihood of successful clinical outcome) and the suppression of resistance emergence.
Ordway Research Institute, Emerging Infections Pharmacodynamics Laboratory, Albany, New York, USA. arnold.louie@medicine.ufl.edu
Arnold
A
Louie
Mariana
M
Castanheira
Weiguo
W
Liu
Caroline
C
Grasso
Ronald N
RN
Jones
Gregory
G
Williams
Ian
I
Critchley
Dirk
D
Thye
David
D
Brown
Brian
B
Vanscoy
Robert
R
Kulawy
G L
GL
Drusano
D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics; D019540:Area Under Curve; D053961:Azabicyclo Compounds / Q000493:pharmacokinetics*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics; D002511:Cephalosporins / Q000493:pharmacokinetics*; D002853:Chromatography, Liquid; D004334:Drug Administration Schedule; D054796:Drug Dosage Calculations; D024881:Drug Resistance, Bacterial; D004357:Drug Synergism; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000188:drug therapy* / Q000382:microbiology; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D053719:Tandem Mass Spectrometry; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics; D000097583:Ceftaroline
D000900:Anti-Bacterial Agents; D053961:Azabicyclo Compounds; D001426:Bacterial Proteins; D002511:Cephalosporins; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases; D000097583:Ceftaroline; C543519:avibactam