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J Antimicrob Chemother. 2011 Jan;66(1):48-53. doi: 10.1093/jac/dkq408. Epub 2010 Nov 14.

Activity of aminoglycosides, including ACHN-490, against carbapenem-resistant Enterobacteriaceae isolates.

Author information

1
Antibiotic Resistance Monitoring & Reference Laboratory, HPA Microbiology Services, London, UK. david.livermore@hpa.org.uk

Abstract

BACKGROUND:

the emergence of carbapenemases in Enterobacteriaceae is driving a search for therapeutic alternatives. We tested ACHN-490, a sisomicin derivative that evades all plasmid-mediated aminoglycoside-modifying enzymes, against 82 carbapenem-resistant Enterobacteriaceae isolates. Comparators included internationally and locally available aminoglycosides. Methods The isolates variously had KPC (n = 12), SME-1 (n = 1), IMP (n = 13), VIM (n = 5), NDM (n = 17) or OXA-48 (n = 19) carbapenemases, or had combinations of impermeability with AmpC (n = 5) or extended-spectrum β-lactamases (n = 10). They included 53 Klebsiella spp., 19 Enterobacter spp., 6 Escherichia coli and 4 others; most were multiresistant. Genes were identified by PCR and sequencing; MICs were measured by CLSI agar dilution.

RESULTS:

ACHN-490 was active at ≤ 2 mg/L against all 65 isolates with carbapenem resistance mechanisms other than NDM enzyme, mostly with MICs of 0.12-0.5 mg/L; isepamicin was active against 63/65 at ≤ 8 mg/L. In contrast, 35% were resistant to gentamicin at 4 mg/L, 61% to tobramycin at 4 mg/L and 20% to amikacin at 16 mg/L. However, 16 of the 17 isolates with NDM-1 enzyme were resistant to ACHN-490, with MICs ≥ 64 mg/L, and these were cross-resistant to all other human-use aminoglycosides tested. Their behaviour was associated with ArmA and RmtC 16S rRNA methylases. Apramycin (a veterinary aminoglycoside) retained its full activity, with MICs of 4-8 mg/L versus strains with armA or rmtC, though resistance was seen in one Klebsiella pneumoniae with AAC(3)-IV (MIC ≥ 256 mg/L).

CONCLUSIONS:

ACHN-490 has potent activity versus carbapenem-resistant isolates, except those also harbouring 16S rRNA methylases; isepamicin is also widely active, though less potent than ACHN-490. Evasion of 16S rRNA methylases by apramycin is noteworthy and may provide a starting point for future aminoglycoside development.

PMID:
21078604
DOI:
10.1093/jac/dkq408
[Indexed for MEDLINE]

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