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J Antimicrob Chemother. 2017 Jan;72(1):153-165. Epub 2016 Sep 15.

High-intensity meropenem combinations with polymyxin B: new strategies to overcome carbapenem resistance in Acinetobacter baumannii.

Author information

1
Laboratory for Antimicrobial Dynamics, NYS Center of Excellence in Bioinformatics & Life Sciences, Buffalo, NY, USA.
2
School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, USA.
3
California Northstate College of Pharmacy, Elk Grove, CA, USA.
4
Center for Pharmacometrics and Systems Pharmacology, College of Pharmacy, University of Florida, Orlando, FL, USA.
5
Department of Microbiology and Immunology and The Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, NY, USA.
6
Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
7
Division of Infectious Diseases and Tropical Medicine, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
8
Catholic University of Daegu, Hayang, South Korea.
9
Departments of Pediatrics, Microbiology and Immunology Weill Cornell Medicine, New York, NY, USA.
10
School of Pharmacy, University of North Carolina Eshelman School of Pharmacy, Chapel Hill, NC, USA.
11
Laboratory for Antimicrobial Dynamics, NYS Center of Excellence in Bioinformatics & Life Sciences, Buffalo, NY, USA btsuji@buffalo.edu.

Abstract

OBJECTIVES:

The pharmacodynamics of polymyxin/carbapenem combinations against carbapenem-resistant Acinetobacter baumannii (CRAB) are largely unknown. Our objective was to determine whether intensified meropenem regimens in combination with polymyxin B enhance killing and resistance suppression of CRAB.

METHODS:

Time-kill experiments for meropenem and polymyxin B combinations were conducted against three polymyxin B-susceptible (MIC of polymyxin B = 0.5 mg/L) CRAB strains with varying meropenem MICs (ATCC 19606, N16870 and 03-149-1; MIC of meropenem = 4, 16 and 64 mg/L, respectively) at 108 cfu/mL. A hollow-fibre infection model was then used to simulate humanized regimens of polymyxin B and meropenem (2, 4, 6 and 8 g prolonged infusions every 8 h) versus N16870 at 108 cfu/mL over 14 days. New mathematical mechanism-based models were developed using S-ADAPT.

RESULTS:

Time-kill experiments were well described by the mathematical mechanism-based models, with the presence of polymyxin B drastically decreasing the meropenem concentration needed for half-maximal activity against meropenem-resistant populations from 438 to 82.1 (ATCC 19606), 158 to 93.6 (N16870) and 433 to 76.0 mg/L (03-149-1). The maximum killing effect of combination treatment was similar among all three strains despite divergent meropenem MIC values (Emax = 2.13, 2.08 and 2.15; MIC of meropenem = 4, 16 and 64 mg/L, respectively). Escalating the dose of meropenem in hollow-fibre combination regimens from 2 g every 8 h to 8 g every 8 h resulted in killing that progressed from a >2.5 log10 cfu/mL reduction with regrowth by 72 h (2 g every 8 h) to complete eradication by 336 h (8 g every 8 h).

CONCLUSION:

Intensified meropenem dosing in combination with polymyxin B may offer a unique strategy to kill CRAB irrespective of the meropenem MIC.

PMID:
27634916
PMCID:
PMC5161044
DOI:
10.1093/jac/dkw355
[Indexed for MEDLINE]
Free PMC Article

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