Use of Silver as an Antibiotic

Someone asked the following question on Quora: “Can silver be used as an antibiotic? If so, what are the potential risks or side effects?

I provided an answer to this question on the forum but thought it worthwhile to add it here as well, with the benefit of a representation of the chemical structure of silver sulfadiazine.

Disclaimer: Please note that the following answer is not intended to provide specific guidance for the management or treatment of a specific medical problem in any individual. Please refer to you health professional if you have any concerns about your health.

Silver possesses antibacterial properties and is used topically either as the metal or as silver salts. It is not absorbed to any great extent and the main problem associated with the metal is argyria, a grey discolouration of the tissues. Argyria is irreversible.

The benefits of silver coated or impregnated catheters in preventing or reducing urinary-tract infection are uncertain, and studies have provided conflicting evidence. There continues to be some debate over the use of silver-imprenated dressings for serious infections; but, where still in use, the most common salts of silver are silver sulfadiazine and silver nitrate.

Silver sulfadiazine

This is used in wound care:

  1. For the prophylaxis and treatment of infections in burn wounds
  2. For conservative management of fingertip injuries
  3. As an adjunct to prophylaxis of infection in skin graft donor sites and extensive abrasions
  4. As an adjunct to short-term treatment of infection in pressure sores
  5. As an adjunct to short-term treatment of infection in leg ulcers

For specific cautions and contraindications, the British National Formulary gives the following information:

“Silver ions exert an antimicrobial effect in the presence of wound exudate; the volume of wound exudate as well as the presence of infection should be considered when selecting a silver-containing dressing. Silver-impregnated dressings should not be used routinely for the management of uncomplicated ulcers. It is recommended that these dressings should not be used on acute wounds as there is some evidence to suggest they delay wound healing. Dressings impregnated with silver sulfadiazine have broad antimicrobial activity; if silver sulfadiazine is applied to large areas, or used for prolonged periods, there is a risk of blood disorders and skin discoloration. The use of silver sulfadiazine-impregnated dressings is contra-indicated in neonates, in pregnancy, and in patients with significant renal or hepatic impairment, sensitivity to sulfonamides, or G6PD deficiency. Large amounts of silver sulfadiazine applied topically may interact with other drugs..”.

Silver Nitrate

This is the active ingredient found in what are commonly referred to as “caustic pencils”. These are used for warts, verrucas and umbilical granulomas. They can cause chemical burns on surrounding skin and can stain the skin.

Quinolones: An Overview

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Quinolines are antibacterial agents that inhibits the supercoiling activity of bacterial DNA gyrase and toposiomerase IV, enzymes which, like human topoisomerase, prevents the excessive supercoiling of DNA during replication or transcription. By inhibiting their function, the drugs thereby inhibit normal cell division.


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The macrolides are a large group of antibacterials mainly derived from Streptomyces spp. and having a common macrocyclic lactone ring to which one or more sugars are attached. They are all weak bases and only slightly soluble in water. Their properties are very similar and in general they have low toxicity and a similar spectrum of antimicrobial activity with cross-resistance between individual members of the group.

The macrolides are bacteriostatic or bactericidal, depending on the concentration and the type of micro-organism, and are thought to interfere with bacterial protein synthesis. They reversibly bind to the 50S ribosomal subunit of the 70S ribosome of sensitive microorganisms, thereby inhibiting the translocation step of protein synthesis, wherein a newly synthesized peptidyl tRNA molecule moves from the acceptor site on the ribosome to the peptidyl (donor) site, and consequently inhibiting RNA-dependent protein synthesis leading to cell growth inhibition and cell death.