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Comparing Kill Kinetics of the Leading Antimicrobials

By Lyn Hanshew, M.D.

Beyond prescribing any silver-based product for its antimicrobial effect, it is necessary in successful practice to distinguish the vast differences in performance amongst competing brands. Clearly silver is not just silver. Major formulation advancements have been made in the last 150 years since the first electrolytically produced colloidal silvers came into existence. To understand the difference in antimicrobial activity between the leading evidence based silver products currently available, we need only compare kill kinetics studies against various benchmark microorganisms.Silver has been known for its medicinal and antimicrobial properties for thousands of years. Hippocrates, “Father of Medicine,” used silver for tissue repair & wound healing. In 69 B.C. silver nitrate was described in the contemporary pharmacopoeia. The ancient civilizations of Greece and Rome used silver to control bodily infection & prevent food spoilage. The King of Persia used silver containers to carry water to prevent contamination. Throughout the ages, the ‘Metal of the Moon’ as it was known to some of the ancients has been used effectively for numerous medicinal purposes.
The most effective antimicrobials within the clinical setting are defined as broad-spectrum; exhibiting bactericidal, virucidal, fungicidal and more in killing effect. As there are a near infinite number of types, and genetic variations of pathogens, antimicrobial research is best accomplished by Association of Analytical Communities (AOAC) standard, invitro kill time studies. This is the same protocol utilized by the Environmental Protection Agency (EPA) in determining the germicidal efficiency of a pesticide/disinfectant. The AOAC protocols are accepted and recognized as standard.
In my investigations, I have compiled kill kinetics data of three of the better known silver-based antimicrobial products currently on the market, which I obtained from the manufacturer’s own websites. Included in this comparative analysis are the independently derived, and independently published kill kinetics test results of Results RNA Advanced Cellular Silver (ACS) 200, American Biotech ASAP silver and Purest Colloids, Inc. MesoSilver against three benchmark microorganisms; Methicillin‐resistant Staphylococcus aureus (MRSA), Candida albicans, and Staphylococcus aureus.
Before we examine the data, a simple defining of terms is necessary:

  • Titer: Synonymous with Microbe Concentration. Titer refers to the number of organisms calculated in the culture prior to testing.
  • Log Reduction: Defines the percentage of kill in logarithms.

Methicillin‐resistant Staphylococcus aureus (MRSA) – Comparative Kill Time Study

MRSA Titer Log Reduction Kill Time
ACS 200* 2,170,000,000 6.64/99.999984% < 3 minutes
ASAP silver 1,900,000 4.98/99.9989% 60 minutes
Meso Silver 1,200,000 Log not provided claimed kill 5 hours

* Performed using AOAC methods
ACS 200 titer is 114,210% greater than ASAP silver titer
ACS 200 titer is 180,833% greater than MesoSilver titer
www.aoac.org – Association of Analytical Communities

  • ACS 200 Extra Strength (tested by AOAC) provides a >6.64 log reduction/99.999984% complete kill in less than 3 minutes.
  • ASAP silver provides a >4.98 log reduction/99.9989% complete kill in 60 minutes.
  • MesoSilver requires 300 minutes to achieve complete kill against MRSA. (Actual Log reduction not provided in published report.)

Microbe Concentrations: The initial microbe concentration (titer) of MRSA used with ACS 200 Extra Strength for testing is significantly larger than the titers used by ASAP silver and MesoSilver. Comparisons are as follows:

MRSA Microbe Concentrations by Product

  • ACS 200 Extra Strength MRSA titer: 2.17 X 109
  • ASAP silver MRSA titer: 1.9 x 106
  • MesoSilver MRSA titer: 1.2 x 106

MRSA Microbe Concentrations Compared

  • The 2.17 X 109 ACS 200 Extra Strength titer is 1,142 times larger than the 1.9 x 106 ASAP silver titer.
  • The 2.17 X 109 ACS 200 titer is 1,808 times larger than the 1.2 x 106 MesoSilver titer.

MRSA Testing Conclusion:

  • ACS 200 Extra Strength achieves complete kill (without a single organism left alive) against 2,170,000,000 MRSA organisms in less than 3 minutes.
  • ACS 200 Extra Strength achieves a significant 20 times faster kill than ASAP silver against Methicillin‐resistant Staphylococcus aureusevidencing a 3 minute/99.999984% >6.64 log reduction versus a 60 minute/99.9989% >4.98 log reduction, while killing an 1,142 times greater number of MRSA organisms.
  • ACS 200 Extra Strength achieves ­­a significant 100 times faster kill than MesoSilver against Methicillin‐resistant Staphylococcus aureusevidencing a 3 minute/99.999984% >6.64 log reduction versus a 300 minute kill time, while killing an 1,808 times greater number of MRSA organisms.

Candida albicans – Comparative Kill Time Study

C. albicans Titer Log Reduction Kill Time
ACS 200* 445,000,000 5.95/99.99989% 2 minutes
ASAP silver 1,300,000 4.83/99.9985% 60 minutes
Meso Silver 12,000 Log not provided claimed kill 24 hours

* Performed using AOAC methods
ACS 200 titer is 34,230% greater than ASAP silver titer
ACS 200 titer is 370,833% greater than MesoSilver titer

  • ACS 200 Extra Strength provides a >5.95 log reduction/99.99989% kill in 2 minutes.
  • ASAP silver provides a >4.83 log reduction/99.9985% kill in 60 minutes.
  • MesoSilver requires 1,440 minutes to achieve complete kill. (Actual Log reduction not provided in published report.)

Microbe Concentrations: The initial microbe concentration (titer) of Candida albicans used with ACS 200 Extra Strength for testing is significantly larger than the titers used by ASAP silver and MesoSilver. Comparisons are as follows:

Candida albicans Microbe Concentrations by Product

  • ACS 200 Extra Strength Candida titer: 4.45 x 108
  • ASAP silver Candida titer: 1.3 x 106
  • MesoSilver Candida titer: 1.2 x 104

Candida Microbe Concentrations Compared

  • The 4.45 x 108 Candida titer (ACS 200 Extra Strength) is 342 times larger than the 1.3 x 106 Candida titer (ASAP silver).
  • The 4.45 x 108 Candida titer (ACS 200 Extra Strength) is 37,083 times larger than the 1.2 x 104 Candida titer (MesoSilver).

Candida Testing Conclusion

  • ACS 200 Extra Strength achieves complete kill (without a single organism left alive) against 445,000,000 Candida organisms in less than 3 minutes.
  • ACS 200 Extra Strength achieves a significant 30 times faster kill than ASAP silver against Candida albicans evidencing a 2 minute/99.99989% >5.95 log reduction versus a 60 minute/99.9985% >4.83 log reduction, while killing a 342 times greater number of Candida organisms.
  • ACS 200 Extra Strength achieves ­­a significant 720 times faster kill than MesoSilver against Candida albicans evidencing a 2 minute/99.99989% >5.95 log reduction versus a 1,440 minute kill time, while killing a 37,083 times greater number of Candida organisms.

Staphylococcus aureus – Comparative Kill Time Study

S. aureus Titer Log Reduction Kill Time
ACS 200* 234,000,000 > 5.37/99.9996% 15 seconds
ASAP silver 2,300,000 > 5.06/99.99914% 60 minutes
Meso Silver 830,000 Log not provided claimed kill 24 hours

* Performed using AOAC methods
ACS 200 titer is 10,173% greater than ASAP silver titer
ACS 200 titer is 28,192% greater than MesoSilver titer

  • ACS 200 Extra Strength provides a >5.37 log reduction/99.9996% kill in 15 seconds.
  • ASAP silver provides a >5.06 log reduction/99.99914% kill in 60 minutes.
  • MesoSilver requires 1,440 minutes to achieve complete kill. (Actual Log reduction not provided in published report.)

Microbe Concentrations: The initial microbe concentration (titer) of Staphylococcus aureus used with ACS 200 Extra Strength for testing is significantly larger than the titers used by ASAP silver and MesoSilver. Comparisons are as follows:

Staphylococcus aureus Microbe Concentrations by Product

  • ACS 200 Extra Strength S. aureus titer: 2.34 x 108
  • ASAP silver S. aureus titer: 2.3 x 106
  • MesoSilver S. aureus titer: 8.3 x 105

Microbe Concentrations Compared

  • The 2.34 x 108 ACS 200 Extra Strength titer is 101 times larger than the 2.3 x 106 ASAP silver titer.
  • The 2.34 x 108 ACS 200 titer is 281 times larger than the 8.3 x 105 MesoSilver titer.

Staph Aureus Testing Conclusion:

  • ACS 200 Extra Strength achieves complete kill (without a single organism left alive) against 234,000,000 S. aureus organisms in less than 15 seconds.
  • ACS 200 Extra Strength achieves a significant 240 times faster kill than ASAP silver against S. aureus evidencing a 15 second/99.9996% >5.06 log reduction versus a 60 minute/99.99914% >5.06 log reduction, while killing 101 times greater number of S. aureus organisms.
  • ACS 200 Extra Strength achieves ­­a significant 5,760 times faster kill than MesoSilver against S. aureus evidencing a 15 second/99.9996% >5.06 log reduction versus a 1,440 minute kill time, while killing a 281 times greater number of S. aureus organisms.

Conclusion

As you can see, the performance of these three silver formulations differs greatly. ACS 200 Extra Strength achieves 100’s of times faster kill in just minutes, against thousands of times greater number of pathogenic microorganisms.
With enhanced killing effect, superior efficacy and patient outcomes are readily discernable with ACS 200 Extra Strength versus competing antimicrobial products. In our clinical experience over the last several years, many practitioners have seen ACS 200 Extra Strength perform extremely well against a host of pathogenic microorganisms, with high benefit and very little risk.

Download Original Kill Time Studies Here

ACS 200 vs MRSA
ACS 200 vs Candida albicans
ACS 200 vs Staph aureus
ASAP Silver vs MRSA
ASAP Silver vs Candida albicans
ASAP Silver vs Staph aureus
Meso Silver vs MRSA
Meso Silver vs Candida albicans
Meso Silver vs Staph aureus