Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2009 Feb;6(1):32-8.
doi: 10.1111/j.1742-481X.2008.00563.x.

Silver resistance in MRSA isolated from wound and nasal sources in humans and animals

Affiliations

Silver resistance in MRSA isolated from wound and nasal sources in humans and animals

Jia V Loh et al. Int Wound J. 2009 Feb.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) colonises skin, nasal passages and dermal wounds. Methods used to manage wounds infected and colonised with MRSA often include the use of topical antiseptics such as ionic silver and iodine. The objectives of this study were to determine the prevalence of silver-resistance (sil) genes in MRSA and methicillin-resistant coagulase-negative staphylococci (MR-CNS) isolated from wounds and nasal cavities of humans and animals, and also to determine the susceptibility of sil-positive and sil-negative MRSA isolates to a silver-containing Hydrofiber (SCH) wound dressing, on planktonic silE-positive and silE-negative MRSA. Polymerase chain reaction was used to determine the presence of three silver-resistance (sil) genes, silE, silP and silS in 33 MRSA and 8 methicillin-resistant staphylococci (MR-CNS). SilP and silS genes were absent in all isolates tested; however, two MRSA strains were found to contain the silE gene, together with one isolate of MR-CNS. Phenotypic resistance of the silE-positive strains and their susceptibility to the SCH dressing was evaluated using the zone of inhibition test on Mueller Hinton agar, and confocal laser microscopy using a live/dead fluorescent stain. Results confirmed that the SCH dressing was effective in killing all MRSA strains with and without the silE gene. First, this study showed that the prevalence of sil genes was low in the isolates investigated; and secondly, that the presence of a silver-resistance gene (silE) in MRSA and MR-CNS did not afford protection to the organism in the presence of a SCH wound dressing. The use of topical antiseptics in chronic wound care should be considered before the use of antibiotics that can result in their overuse and the risk of further resistance.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Analysis of polymerase chain reaction products from silver‐resistance (sil)E gene‐specific primers, and methicillin‐resistant Staphylococcus aureus and methicillin‐resistant coagulase‐negative staphylococci isolates of 152 (lane 2), 151 (lane 3) and 133/03 (lane 4) from wounds via agarose gel electrophoresis. Lane 1, Ready‐Load™ 1 Kb Plus DNA Ladder (Invitrogen); lane 5, water control; lane 6, Escherichia coli J53, negative control; lane 7, EC702 (CN, sil‐positive Enterobacter cloacae); 8, pKM1, positive control. The bands of 400 bp in size corresponds to silE. Analysis was carried out by staining the gel with ethidium bromide and using Gene Genius Bioimaging System version 6.03 (Syngene, Synoptic Ltd, Cambridge, UK).
Figure 2
Figure 2
Confocal laser microscope images showing the efficacy of ionic silver present in SCH on methicillin‐resistant Staphylococcus aureus (MRSA) viability. Bacteria labelled with a live:dead BacLight stain were shown as green when alive and red when dead. Incubation of a non silver‐resistant strain of MRSA with SCH showed cell death occurred within 3 hours of inoculation (B), compared with the NSCH control, where cells remained viable (A). MRSA 133/03, found to contain silE, showed no significant cell death after 3 hours with SCH (D). After 24 hours, low levels of cell death were apparent (F) and after a maximum of 48 hours, all bacteria were dead (H). Incubation with a NSCH (control) showed that cells survived within the dressing when silver was absent (C, E and G).

Similar articles

Cited by

References

    1. Thomas S. MRSA and the use of silver dressings: overcoming bacterial resistance. World Wide Wounds, 2004. Available at http://www.worldwidewounds.com/2004/november/Thomas/Introducing‐Silver‐D....
    1. Jones RN, Ballow CH, Biedenbach DJ, Deinhart JA, Schentag JJ. Antimicrobial activity of quinupristin‐dalfopristin (RP 59500, Synercid) tested against over 28,000 recent clinical isolates from 200 medical centers in the United States and Canada. Diagn Microbiol Infect Dis 1998;31:437–51. - PubMed
    1. Hiramatsu K, Hanaki H. Glycopeptide resistance in staphylococci. Curr Opin Infect Dis 1998;11:653–8. - PubMed
    1. Sievert DM, Boulton ML, Stoltman G, Johnson D, Stobierski MG, Downes FP, Somsel PA, Rudrik JT, Brown W, Hafeez W, Lundstrom T, Flanagan E, Johnson R, Mitchell J, Chang S. Staphlococcus aureus resistant to vancomycin. MMWR Morb Mortal Wkly Rep, 2002;51:565–7. - PubMed
    1. Jones S, Bowler PG, Walker M. Antimicrobial activity of silver‐containing dressings is influenced by dressing conformability with a wound surface. Wounds 2005;17:263–70.

MeSH terms

Substances