Abstract
The aminoglycoside-modifying enzyme AAC(6')-Ib is common among carbapenem-resistant Klebsiella pneumoniae (CR-Kp) strains. We investigated amikacin (AMK) activity against 20 AAC(6')-Ib-producing CR-Kp strains. MICs clustered at 16 to 32 μg/ml. By the time-kill study, AMK (1× and 4× the MIC) was bactericidal against 30% and 85% of the strains, respectively. At achievable human serum concentrations, however, the majority of strains showed regrowth, suggesting that AAC(6')-Ib confers intermediate AMK resistance. AMK and trimethoprim-sulfamethoxazole (TMP-SMX) were synergistic against 90% of the strains, indicating that the combination may overcome resistance.
Copyright © 2014, American Society for Microbiology. All Rights Reserved.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetyltransferases / genetics*
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Acetyltransferases / metabolism
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Amikacin / pharmacology*
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Anti-Bacterial Agents / pharmacology*
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Bacterial Proteins / genetics*
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Bacterial Proteins / metabolism
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Drug Resistance, Bacterial / drug effects
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Drug Resistance, Bacterial / genetics
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Drug Synergism
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Gene Expression
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Humans
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Klebsiella Infections / microbiology
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Klebsiella pneumoniae / drug effects*
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Klebsiella pneumoniae / enzymology
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Klebsiella pneumoniae / genetics
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Klebsiella pneumoniae / growth & development
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Microbial Sensitivity Tests
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Trimethoprim, Sulfamethoxazole Drug Combination / pharmacology*
Substances
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Anti-Bacterial Agents
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Bacterial Proteins
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Trimethoprim, Sulfamethoxazole Drug Combination
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Amikacin
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Acetyltransferases