David Macinga, PhD Principal Scientist, GOJO Industries, Inc

David Macinga, PhD
Principal Scientist, GOJO Industries, Inc

Dr Macinga reviewed the history of hand hygiene using chemicals starting with Semmelweis and Koch through the CDC and WHO. He highlighted Dr Phillip Price’s studies in the 1930-50’s that documented the effectiveness of alcohol based hand rubs. He reviewed the efficacy of Alcohol Based Hand Rubs (ABHR).





Log Reduction          Percent Reduction of Bacteria 


1                                                90%

2                                               99%      

3                                               99.9%


Example: Start with 1 million bacteria

  1. log reduction: 900,000 are skilled and 100,000      remain
  2. log reduction: 990,000 are skilled and 10,000      remain
  3. log reduction: 999,000 are skilled and 1,000      remain

He also shared the significance of alcohol efficacy based on dose response. After a specific amount increasing the dose does not provide much additional benefit. There is a “threshold” concentration when alcohol becomes bactericidal.

4 log10 reduction is achieved with 40% for Gram-negative bacteria and 50% for Gram-positive bacteria. Activity does not improve above this level.

Alcohol kills microorganism by: damages cell membrane, loss of cell integrity, inactivates proteins (“denatures”), acts and evaporates very rapidly, and is not associated with resistance development.

Dr Macinga reviewed the difference in resident and transient colonization of the hands:

Resident microflora: Normal inhabitants of the skin: colonize deeper layers of the skin, difficult to remove, target for pre-surgical hand scrubs/rubs

Transient microflora: visitors to the skin, picked up from environment: on superficial layers of skin, easier to remove, target for alcohol-based hand rubs

Hand Hygiene is the single most important intervention to help reduce the spread of HAI.

ABHRs are critical to help reduce the spread of healthcare-associated infections.

It is important to understand ABHR test methods when evaluating and interpreting product claims. Data from in vivo methods is essential to differentiate ABHR efficacy. Be cautious of “99.99999999999% game”. There is still opportunity for improvement of hand hygiene technology and test methods.

Dr Macinga discussed the nature of compliance with hand hygiene standards. The ABHR may be effective but must be used to be of value. Although most clinicians do not perceive that the volume of sanitizer is important it has been shown to be of value in testing effectiveness.

Clinical benefit is achieved when there is a reduction in pathogen transmission and there are reduced infections.

ABHRs should be considered from a whole system approach to maximize clinical effectiveness:

  • Formulation matters
  • Efficacy should be judged on in vivo FDA performance      criteria and not on alcohol content
  • Dispenser output matters
  • When evaluating in vivo data, the test volume relative      to dispenser output is critical

Product acceptance and tolerability is critical to      driving compliance –End user trials of both formulations and dispensers      should be conducted to aid in purchasing decisions.

To get a detailed run-down of what is going on with our committees and SIGS, please visit April General Meeting Minutes