Loading…

Cryptic silver resistance is prevalent and readily activated in certain Gram-negative pathogens

To assess the prevalence of cryptic silver (Ag+) resistance amongst clinical isolates of Gram-negative bacteria, and to examine how overt Ag+ resistance becomes activated in such strains. Established methods were used to determine the susceptibility of 444 recent clinical isolates to Ag+, and to eva...

Full description

Saved in:
Bibliographic Details
Published in:Journal of antimicrobial chemotherapy 2017-11, Vol.72 (11), p.3043-3046
Main Authors: Elkrewi, Elham, Randall, Christopher P, Ooi, Nicola, Cottell, Jennifer L, O'Neill, Alex J
Format: Article
Language:English
Subjects:
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:To assess the prevalence of cryptic silver (Ag+) resistance amongst clinical isolates of Gram-negative bacteria, and to examine how overt Ag+ resistance becomes activated in such strains. Established methods were used to determine the susceptibility of 444 recent clinical isolates to Ag+, and to evaluate the potential for overt Ag+ resistance to emerge in susceptible isolates by spontaneous mutation. The genetic basis for Ag+ resistance was investigated using PCR amplification and DNA sequencing. None of the isolates tested displayed overt Ag+ resistance. However, upon silver challenge, high-level Ag+ resistance (silver nitrate MIC >128 mg/L) was selected at high frequency (10-7 to 10-8) in 76% of isolates of Enterobacter spp., ∼58% of isolates of Klebsiella spp. and ∼0.7% of isolates of Escherichia coli. All strains in which Ag+ resistance could be selected harboured the sil operon, with resistance apparently resulting from activation of this system as a consequence of single missense mutations in silS. By contrast, Ag+ resistance was not selected in isolates lacking sil, which included all tested representatives of Pseudomonas aeruginosa, Acinetobacter spp., Citrobacter spp. and Proteus spp. Whilst overt Ag+ resistance in Gram-negative pathogens is uncommon, cryptic Ag+ resistance pertaining to the sil operon is prevalent and readily activated in particular genera (Enterobacter and Klebsiella).
ISSN:0305-7453
1460-2091
DOI:10.1093/jac/dkx258