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J Antimicrob Chemother. 2019 Jan 9. doi: 10.1093/jac/dky546. [Epub ahead of print]

In vitro activity of apramycin against multidrug-, carbapenem- and aminoglycoside-resistant Enterobacteriaceae and Acinetobacter baumannii.

Author information

1
Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, CH-8006 Zürich, Switzerland.
2
Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.
3
Department of Laboratory Medicine, National University Hospital, 5 Lower Kent Ridge Road, 119074 Singapore, Singapore.
4
Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75123 Uppsala, Sweden.
5
Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois at Chicago, 900 South Ashland Avenue, MBRB 4170, Chicago, IL 60607, USA.
6
Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202, USA.

Abstract

Objectives:

Widespread antimicrobial resistance often limits the availability of therapeutic options to only a few last-resort drugs that are themselves challenged by emerging resistance and adverse side effects. Apramycin, an aminoglycoside antibiotic, has a unique chemical structure that evades almost all resistance mechanisms including the RNA methyltransferases frequently encountered in carbapenemase-producing clinical isolates. This study evaluates the in vitro activity of apramycin against multidrug-, carbapenem- and aminoglycoside-resistant Enterobacteriaceae and Acinetobacter baumannii, and provides a rationale for its superior antibacterial activity in the presence of aminoglycoside resistance determinants.

Methods:

A thorough antibacterial assessment of apramycin with 1232 clinical isolates from Europe, Asia, Africa and South America was performed by standard CLSI broth microdilution testing. WGS and susceptibility testing with an engineered panel of aminoglycoside resistance-conferring determinants were used to provide a mechanistic rationale for the breadth of apramycin activity.

Results:

MIC distributions and MIC90 values demonstrated broad antibacterial activity of apramycin against Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Morganella morganii, Citrobacter freundii, Providencia spp., Proteus mirabilis, Serratia marcescens and A. baumannii. Genotypic analysis revealed the variety of aminoglycoside-modifying enzymes and rRNA methyltransferases that rendered a remarkable proportion of clinical isolates resistant to standard-of-care aminoglycosides, but not to apramycin. Screening a panel of engineered strains each with a single well-defined resistance mechanism further demonstrated a lack of cross-resistance to gentamicin, amikacin, tobramycin and plazomicin.

Conclusions:

Its superior breadth of activity renders apramycin a promising drug candidate for the treatment of systemic Gram-negative infections that are resistant to treatment with other aminoglycoside antibiotics.

PMID:
30629184
DOI:
10.1093/jac/dky546

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