Can microbes grow resistance to nano silver? So what does real science say about the potential for creating silver-resistance in pathogenic microbes? 

Research on bacterial resistance to silver nanoparticles

According to Lucian Lucia, associate professor of chemistry at North Carolina State University, and chemist George John of City College of New York, bacteria cannot build up a resistance to silver nanoparticles as they can to antibiotics, because of the way the silver nanoparticle attacks — destroying the structure of the cells and killing them.

Antibiotics, on the other hand, suppress the activity of bacteria but don’t necessarily kill them. “That’s the beauty of silver,” Lucia says. “There’s no way to develop a serious resistance to it.”

Writing in the journal BioMetals in 1998, in a study titled “Multiple Parameters for the Comprehensive Evaluation of the Susceptibility of Escherichia coli to the Silver Ion,” researchers G. Zhao, and S.E. Stevens stated:

“With the rise of antibiotic-resistant bacteria, silver is re-emerging as a modern medicine because pathogenic organisms have generally failed to develop an immunity to it (i.e., the silver ion).”

According to researcher AB Lansdown, writing in the Journal of Wound Care, April 2002:

“Silver products have two key advantages: they are broad-spectrum antibiotics and are not yet associated with any significant drug resistance.”

According to researcher A. Dwight Webster, writing in Clinical Orthopaedics and Related Research, in a study titled “Silver Anode Treatment of Chronic Osteomyelitis”:

“The silver cation is known to have an exceptionally broad spectrum involving gram-positive, gram-negative, aerobic and anaerobic microorganisms… resistance to silver ions is rare.”

According to Herbert Slavin, M.D., founder and director of the Institute of Advanced Medicine, Lauderhill, Florida:

“Reports of any pathogens developing resistance to ionic silver are rare. Some reports indicate it even kills drug-resistant strains of germs. Ionic silver is also a powerful tissue-healing agent, so much so that it has been used topically for decades in burn centers and currently represents one of the fastest growing sectors – if not the fastest growing sector – in wound care today.”


Research on bacterial resistance to silver nano-particles – google image 

And according to Steve Thomas, PhD, Director Surgical Materials Testing Laboratory Bridgend, Wales, UK, in an article titled, “MRSA and the use of silver dressings: overcoming bacterial resistance”:

“Although some bacteria can develop resistance to silver, this is not regarded as a serious problem as available evidence suggests that most preparations capable of delivering sustained silver-ion release are effective against MRSA and VRE, and as yet no resistant strains have been encountered clinically.

It follows, therefore, that any silver-containing dressing that shows acceptable levels of activity against a range of non-resistant bacterial species should show comparable activity against antibiotic-resistant strains of the same organism.”

As stated by silver researcher S.M. Foran, writing in Therapeutic Properties of Silver: an Historical and Technical Review:

“Another benefit to using silver is that it does not appear to create the same amount of resistance in bacteria as traditional antibiotics.

Ian Chopra, Professor of Microbiology at the University of Leeds, reported in a 2007 article in the Journal of Antimicrobial Chemotherapy that there are fewer than twenty published reports of silver resistance in bacteria.

Professor Chopra went on to indicate that ‘current evidence suggests the clinical threat [due to silver resistance] is low’ because of the ‘multifaceted mode of action of the silver ion.’”

Silver’s Multi-Faceted Mode of Action

You see, unlike antibiotic drugs which generally kill pathogens through a single course of action, silver works in a multi-faceted manner, attacking infectious microorganisms from many different angles.


Therefore, it is very difficult and extremely rare for pathogens to become “resistant” to silver.

Generally speaking, if one facet of silver’s antimicrobial arsenal fails to work on a specific pathogen, another facet will do the job handily.

Infectious disease specialist Dr. David Weber agrees, arguing that the use of silver in commercial products poses very little danger of creating silver-resistant microbes, due to silver’s multiple modes of operation.

As reported in the Los Angeles Times, in August of 2008:

“…Dr. David Weber, an infectious disease and public health expert at the University of North Carolina in Chapel Hill, isn’t convinced that silver resistance will prove much of a problem.

Resistance to antibiotics occurs quite readily in bacteria once prolonged exposure to, say, penicillin, occurs. But there’s little reason to suppose that resistance to silver would develop so easily, he says.

An antibiotic like penicillin works by hitting a bacterium in a limited fashion, at specific sites. Because the killing is done precisely, the bacterium has a good chance of developing a mutation that would confer resistance.

In contrast, silver kills microbes in a broad, unspecific fashion – like tossing a bomb at a bacterium. It hits many essential points such as a bacterium’s entire respiratory system. This makes it much more difficult for silver-resistance to develop.

And even if tolerance did develop, Weber says, increasing the dose of silver the bacterium is exposed to will solve the problem in most cases.”

In short, microbes simply don’t grow resistant to silver anywhere near as easily as they do to synthetic antibiotic drugs, thanks in large part to silver’s broad spectrum of action.

And even if a microbe does grow resistant to silver, increasing the dosage tends to take care of the problem!

Can Pathogens Become Silver-Resistant Due to Prolonged Exposure to Silver?


Only about 20 pathogens have demonstrated an ability to develop silver resistance – google image 

That’s not to say there are no cases whatsoever of silver-resistant microbes. Indeed, there are a small handful of cases.

But out of the 20,000 catalogued pathogens in existence (and millions more that remain uncatalogued), only a very few have been found to be silver-resistant.

In fact, only about 20 pathogens have demonstrated an ability to develop silver resistance, and then, only to varying degrees.

According to the Immunogenic Research Foundation, these include sub-species of the following 20 pathogens, which have been shown to “exhibit various degrees of resistance to the bactericidal effects of silver-based drugs”:

1. Acinetobacter baumani

2. Citrobacter freundii

3. Entamoeba histolytica cysts

4. Enterobacter cloacae

5. Enterobacteriaceae

6. Enterococcus hiraea

7. Escherichia coli

8. Helicobacter pylori

9. Klebsiella pneumoniae

10. Mycobacteria

11. Pseudomonas aeruginosa,

12. E. cloacae

13. Ps. stutzeri

14. Ps. putida

15. Proteus mirabilis

16. Salmonella typhimurium

17. Staphylococcus aureus

18. Thiobacillus ferro-oxidans

19. Thiobacillus thio-oxidans

20. Vegetative B. Cereus Spores

In each case above, only some sub-species of the pathogens listed appear to be able to develop resistance to silver’s antimicrobial qualities.

And again, it is important to note that only varying degrees of resistance have been demonstrated in clinical studies.


In other words, few if any of these strains have demonstrated an ability to become completely resistant to silver. This means switching to a more powerful form of silver, or simply increasing the dosage of silver, will generally kill these “silver-resistant” sub-species.

Should This Be Any Surprise?

Should it be any surprise that in some rare cases, a sub-species or strain of pathogenic microorganism has demonstrated at least some small resistance to the antimicrobial qualities of silver?

Of course not. No more so that it should be a surprise to find that some rare species of fish can survive out of water for long periods of time, and others can crawl out of the water and walk across dry land.

Nature is just like that. Nothing follows the rules 100% of the time. And no antimicrobial substance on the face of the earth is 100% effective every time it’s used.

For example, generally speaking, silver-based antimicrobials are highly effective against many strains of Klebsiella pneumoniae, a potentially deadly pathogen that is frequently picked up by surgical patients in hospitals


But at least one sub-species of Klebsiella has been demonstrated in laboratory studies to become resistant to silver, too, after being exposed to it multiple times.

What researchers did was expose a test tube colony of the pathogen, grown in a saline nutrient broth, to small amounts of silver – just enough to kill off the weaker pathogens in the colony.

Then they repeated the process, each time adding a tiny bit more silver than the last. By the time they did this multiple times (11 separate times in the study I read, going by memory), the remaining pathogens appeared to be silver-resistant.

This was a test-tube study, of course. But it nevertheless demonstrates the possibility that a subspecies of Klebsiella can actually become silver-resistant under the right conditions of repeated exposure to a silver-based product.

Here’s what researcher L.K. Gupta, from the Department of Microbiology, Panjab University, India stated regarding the silver-resistance developed by a sub-species of Klebsiella, writing in medical journal Folia Microbiologica:

A silver-resistant mutant of Klebsiella pneumoniae B-5 was produced by passaging in nutrient broth containing graded concentrations of silver nitrate up to 150 ppm.

The development of silver resistance in the strain resulted in rough colonies, decrease in cell size, carbohydrate content and change in klebocin pattern.

The virulence of the AgR strain as checked by the burn wound model decreased as the mutant could not establish itself in the skin and spleen of the animals and the organism was cleared more efficiently by human lymphocytes than the parent AgS strain.

In other words, using the B-5 strain of Klebsiella, the researchers were able to add increasingly high concentrations of silver nitrate (up to 150 ppm) until they produced a strain that was resistant to the silver.

However, the silver-resistant strain suffered from a significantly reduced cell size, and was considerably weaker in virulence (i.e., ability to cause infection) than the parent strain.

Indeed, the silver-resistant strain, though alive, could no longer establish functional infectivity in the skin and spleen of animals used in the research.

And the body’s natural immune system processes readily cleared the microbe, indicating it had been so weakened by the repeated exposure to silver that it was no longer a significant threat.

So what’s the problem? Thanks to the silver, even the pathogens that didn’t die during exposure to silver still lost their functional infectivity!

As you can see, this is hardly the stuff an impending apocalypse of silver-resistant microbes is made of.

From the Radical Environmentalists

What’s more, the good news the radical environmentalists will never tell you is this:

It is well known that certain strains of Klebsiella pneumoniae have also become resistant to Big Pharma’s antibiotic drugs. But…a whopping 75% of these antibiotic-resistant strains are stopped cold by silver-based antimicrobials!


Once again, writing in the medical journal Folia Microbiologica, researcher N. Kapoor of the Department of Microbiology, Panjab University, India, states:

“Multidrug-resistant (MDR) clinical isolates of Klebsiella pneumoniae were checked for their sensitivity toward silver nitrate by the tube-dilution method. Nearly 75% of MDR strains could be successfully inhibited by 5 mg/L of silver nitrate.”

In other words, the vast majority of the strains of this potentially deadly pathogen that are no longer killed by prescription antibiotic drugs have been shown to be inhibited by…(drum roll, please) antimicrobial silver!

Considering the fact that up to 40% of all victims of multiple-drug resistant Klebsiella infections die from their infections, that’s the news that shouldbe trumpeted from the headlines of all of the science magazines and medical periodicals.

Simply put, antimicrobial silver kills most drug-resistant strains of Klebsiella!

Poorly Designed Studies

Another interesting point, according to the Immunogenic Research Foundation, is that many of the studies demonstrating silver resistance by pathogens such as Klebsiella have had some serious shortcomings and outright flaws.

First and foremost, the researchers apparently never used nanoscale oligodynamic silver (i.e., small particles of highly bioactive silver). Instead, they used silver salt compounds (such as silver nitrate), which are only mildly bioactive by comparison. So they were operating at a disadvantage from the start.

“The experimental designs typically utilized silver salt compounds, which deliver poor amounts of bioactive silver,” the foundation reports in its white paper titled “Microbial Multi-Drug Resistance (MDR) And Oligodynamic Silver.”

What’s more, in many cases the broth cultures in which the pathogens for these studies were grown were composed of substances (or concentrations of substances) not normal to the human body and which are widely known to negate silver’s effectiveness.


As the Immunogenic Research Foundation white paper points out:

“Another most common problem of these experimental designs was the inadvertent culture contamination with various salts, something which will reduce silver efficacy.”

In other words, some of the salts used in the broth cultures the microbes were being grown in are known to interfere with the antimicrobial effectiveness of silver. Therefore, what appeared to have been silver-resistance developed by the bacteria, was more likely the result of neutralization of the silver by the ingredients in the broth the bacteria were grown in!

The microbes didn’t grow resistant. The silver was simply robbed of its antimicrobial qualities before it could do its job.

This makes sense, since researcher N. Grier, writing in the journal of Disinfection, Sterilization and Preservation way back in 1985, pointed out in an article titled “Silver and Its Compounds” that:

“Some so-called Ag+ resistant microorganisms may result from an apparent neutralization of the metal’s inhibitory action or other assay artifacts.

These include the presence of chelators such as serial amino acids, constituents of hard water, different buffers, light, incubation temperature, and particularly, soluble components of trypticase soy agar (TSA) and tryptose glucose extract agar (TGE).”

Plus, the researcher above points out that other confounding factors such as excessive light and extreme temperatures (silver is hyper-sensitive to both light and temperature, which for example, is why silverware tarnishes) may also have played a role in de-activating the silver.

What’s more, in many cases these particular growth cultures were apparently not comparable to the biological fluids found in living tissues.

According to the white paper from the Immunogenic Research Foundation:

“The colloidal state and dynamics of living tissues is at odds with typical culture techniques and mediums, and brings about the unfortunately situation of requiring readers to compare apples to oranges.”

In other words, the research only demonstrated silver’s supposed reduction in efficacy against these pathogens under artificial laboratory conditions not relevant to typical human biological conditions.

In Conclusion


Kentary Nano Silver 

Silver is one of the small handfuls of powerful substances nature has provided for man to extract from the environment and use against pathogens.And it has worked very effectively for thousands upon thousands of years.

It’ss not perfect. It’s not “God.” But it’s extremely effective against pathogens, including viruses, and even against the emerging superpathogens such as MRSA that are resistant to Big Pharma’s most powerful antibiotic drugs.

Indeed, antimicrobial silver is exactly what’s needed in this Age of Strange Diseases in which we now live.

While more work needs to be done in developing effective protocols for the use of silver against infectious microorganisms and related disease in humans –

– there appears at this point in time to be no significant reason whatsoever to be concerned about the development of silver resistance among pathogens.

As we’ve seen above, studies purporting to demonstrate the development of silver resistance have in many cases been poorly conducted, using less bioactive forms of silver (such as silver nitrate) rather than oligodynamic silver (silver that is highly bioactive in even small amounts).

What’s more, many of the poorly designed studies used substances that are known to neutralize silver, creating the appearance that the microbes became resistant to the silver when in reality the silver had simply been rendered inert by the poorly chosen ingredients, or levels of silver used were simply too low to be effective. Other studies simply didn’t use high enough concentrations of silver.


Leave a comment

Item added to cart.
0 items - VND0