Synergy testing by etest, microdilution checkerboard, and time-kill methods for pan-drug-resistant Acinetobacter baumannii

Madhuri M. Sopirala, Julie E. Mangino, Wondwossen A. Gebreyes, Beth Biller, Tammy Bannerman, Joan Miquel Balada-Llasat, Preeti Pancholi

Research output: Contribution to journalArticle

126 Citations (Scopus)

Abstract

Pan-drug-resistant (PDR) Acinetobacter baumannii is an important nosocomial pathogen that poses therapeutic challenges. Tigecycline alone or in combination with agents such as colestimethate, imipenem, and/or amikacin is being used clinically to treat PDR A. baumannii infections. The purpose of this study was to compare in vitro susceptibility testing by epsilometric (Etest) methods and the checkerboard (CB) method with testing by time-kill analysis. PDR A. baumannii clinical strains representing eight unique pulsed-field gel electrophoresis clones selected from a total of 32 isolates were tested in vitro with tigecycline, colestimethate, imipenem, and amikacin in single- and two-drug combinations by using two different methods of Etest (with a fixed ratio method [method 1] and with the incorporation of the active drug in medium [method 2]) and by using CB. The three-drug combination of imipenem, tigecycline, and amikacin was also tested by CB. These results were compared to time-kill results. Synergy was consistently detected with the imipenem plus colestimethate and tigecycline plus imipenem combinations. The Etest method with active drug incorporated into the agar allowed us to detect synergy even in the presence of the active drug and was more comparable to CB and time-kill tests. Synergy was detected with the three-drug combination of imipenem, tigecycline, and amikacin by both CB and time-kill methods among several tested clones. These findings indicate the utility of synergy testing to predict activity of specific antibiotic combinations against PDR A. baumannii.

Original languageEnglish (US)
Pages (from-to)4678-4683
Number of pages6
JournalAntimicrobial Agents and Chemotherapy
Volume54
Issue number11
DOIs
StatePublished - Nov 1 2010
Externally publishedYes

Fingerprint

Disk Diffusion Antimicrobial Tests
Acinetobacter baumannii
Imipenem
Amikacin
Pharmaceutical Preparations
Drug Combinations
Acinetobacter Infections
Clone Cells
Pulsed Field Gel Electrophoresis
Agar
tigecycline
Anti-Bacterial Agents

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

Synergy testing by etest, microdilution checkerboard, and time-kill methods for pan-drug-resistant Acinetobacter baumannii. / Sopirala, Madhuri M.; Mangino, Julie E.; Gebreyes, Wondwossen A.; Biller, Beth; Bannerman, Tammy; Balada-Llasat, Joan Miquel; Pancholi, Preeti.

In: Antimicrobial Agents and Chemotherapy, Vol. 54, No. 11, 01.11.2010, p. 4678-4683.

Research output: Contribution to journalArticle

Sopirala, Madhuri M. ; Mangino, Julie E. ; Gebreyes, Wondwossen A. ; Biller, Beth ; Bannerman, Tammy ; Balada-Llasat, Joan Miquel ; Pancholi, Preeti. / Synergy testing by etest, microdilution checkerboard, and time-kill methods for pan-drug-resistant Acinetobacter baumannii. In: Antimicrobial Agents and Chemotherapy. 2010 ; Vol. 54, No. 11. pp. 4678-4683.
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