Laboratory Results

As you can see from this report, there is a narrow range where the concentration of colloidal silver works the very best. If the concentration is a bit too low, then as one can see with the Staphylococcus aureus, the growth is a bit higher at 9 PPM than it is at 15 PPM. Similarly, there is a point above the 15 to 25 PPM level where the effectiveness of the colloidal silver goes down as well. Clearly, the adage, more is better, is not necessarily true when it comes to the effectiveness of colloidal silver. It is interesting to note that the early-part-of-century reports have pretty much the same results as the report from Molecular Biologics. There is an optimum concentration range (15 to 25 PPM) for colloidal silver.

This study by Molecular Biologics is one of the most recent laboratory studies acquired. There have been many other similar studies conducted. Some have been done in the last five or six years. However, the majority of studies on the effectiveness of various concentrations of colloidal silver were conducted before 1938. In fact, it has been the 1916's to the 1919's in which we find the greatest number of reports on the subject.

Offered by Pat.

March 6, 1996 - California, Molecular Biologics Laboratory Report

Using Colloidal Silver solution as a disinfectant against Salmonella thyphi, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

A. Culture Media

The nutrient broth for growing the microbes contained 5.0 grams of beef extract and 20 grams of peptone in one liter of purified water. 5 mls of broth was pipetted into test tubes and autoclaved.

 

B. Microbes

Using four regular nutrient broth test tubes, one disk of each microbe was added to each one. All four test tubes were incubated for 24 hours at 35 degrees Celsius. A blank control of the broth was also incubated.

 

C. Reagents

Using a 1.0% silver solution and nutrient broth, dilutions of silver solution were made: 0.10%, 0.05%, 0.025%, 0.005%, and 0.0025%. Four sets of the dilutions were made and inoculated with each microbe. The four sets of inoculated silver solution dilutions were incubated at 35 degrees Celsius for 24 hours.

 

D. Results

Silver content and a microscopic exam using a hemacytometer was done on each dilution for each microorganism. The blank nutrient broth showed no growth.

Salmonella thyphi: Microscopic exam of the control showed >25 colonies per counting square.
10, 13 and 24 PPM Silver... no growth
84 PPM Silver... >2 colonies per counting square
179 PPM Silver... 5 colonies per counting square
Conclusion: Results showed luxuriant growth without silver and a 80 to 100% reduction of microbes with silver.

Staphylococcus aureus: Microscopic exam of the control showed >30 colonies per counting square.
9 PPM Silver... 3 colonies
15 PPM Silver... 1 colony
43 PPM Silver... >1 colony
84 PPM Silver... 8 colonies
139 PPM Silver... 5 colonies
Conclusion: 73 to near 100% reduction of microbes with silver.

Pseudomonas aeruginosa: Microscopic exam of control showed >30 colonies per counting square.
18 PPM Silver... >1 colony
44 PPM Silver... 2 colonies
89 PPM Silver... 3 colonies
178 PPM Silver... 3 colonies
Conclusion: 90 to near 100% reduction in microbes with silver.

Escherichia coli: Microscopic exam of the control showed >15 colonies per counting square.
10, 40, and 44 PPM Silver... No Growth
70 PPM Silver... 2 colonies
89 PPM Silver... 1 colony
Conclusion: 87 to 100% reduction with silver.