Colloidal Silver

Discussion

Antimicrobial (1,2)

The use of silver in medicine dates back thousands of years, and scientists have long known that the metal is a potent antibacterial agent.

Silver ions perform their deadly work by punching holes in bacterial membranes and wreaking havoc once inside. They bind to essential cell components like DNA, preventing the bacteria from performing even their most basic functions. But silver’s “zombie effect” has gone unrecognized—until now. To uncover this grisly mechanism, scientists first killed a sample of the bacterium Pseudomonas aeruginosa using a solution of silver nitrate. Then, they carefully separated the dead bacteria from the silver solution. When they exposed living bacteria to the dead, they witnessed a microscopic massacre: Up to 99.99% of the living bacteria met their doom.

Antifungal, Anti- Candida (3, 4, 5)

An increase in multidrug-resistant fungal strains and fungal infections have become a major health concern, given that invasive infections by Candida, Cryptococcus, and Aspergillus species have led to millions of mortalities. Conventional antifungal drugs including polyenes, echinocandins, azoles, allylamins, and antimetabolites have been used for decades, but their limitations include off-target toxicity, drug-resistance, poor water solubility, low bioavailability, and weak tissue penetration. Due to the proven antifungal activity of silver nanoparticles (AgNPs), there is a growing interest in their use in the treatment of fungal infections.  Silver NPs exhibit high antifungal activity against pathogenic Candida spp. at the concentrations around 1 mg/L of Ag.

Anti-Biofilm (6, 7, 8) 

Colloidal silver is an alternative medicine consisting of silver particles suspended in water. After using this solution as a nasal spray, the symptoms of a previously recalcitrant Staphylococcus aureus (S. aureus)-infected chronic rhinosinusitis patient were observed to have improved markedly. At 20 μL colloidal silver reduced biofilm by 98.9%. A maximum biomass reduction of 99.8% was reached at both 100 and 150 μL colloidal silver.

Nontuberculous mycobacteria (NTM) along with Mycobacterium tuberculosis complex and Mycobacterium leprae belong to the family of Actinobacteria and the genus of Mycobacteria. NTM can cause difficult to treat lung infections in susceptible individuals and skin and soft tissue infections (SSTIs) where they usually present as abscesses, sporotrichoid nodules or ulcers. These SSTIs typically occur after trauma, surgery and cosmetic procedures and their prevalence has been increasing in recent years.  NTM can also form biofilms and internalize within macrophages and have intrinsic or inducible resistance to most antibiotics and immune system surveillance systems. Colloidal Silver in concentrations of 0.7 ppm and 22 ppm kills the M. abscessus and Mycobacterium avium intracellular complex (MAIC) in planktonic and biofilm forms.

Silver Nanoparticles (AgNPs) highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes.

Anti-Parasite (9,10) 

Colloidal Nanosilver exerted anthelmintic action superior to one of the positive controls (Benzimidazole), and almost at par to another positive control (Ivermectin). At concentrations ≥ 2 ppm, it could kill all the worms present in the experimental well. Lower concentrations of silver were found to have a cuticle-damaging action on worms.

Recently, AgNPs synthesized from plant extracts have exhibited outstanding antiparasitic effects, with a shorter duration of use and enhanced ability to inhibit parasite multiplication compared to traditional antiparasitic drugs.