Background

The transmission of pathogenic microorganisms by hand contact has steadily increased over the past decade. This has occurred despite the abundance of new disinfectants and hand sanitizer dispensers everywhere we look. In addition, new multiple-drug resistant bacteria are becoming more common, in part due to the misuse of many common antibiotics.

However, the largest culprit of this increase is most likely due to non-compliance with standard hand hygiene recommendations.

Our hands are a primary route of transmission of an infectious agent from one person to another.  In American hospitals alone, approximately two million patients per year contract an infection, with about one in twenty dying from this infection. That’s 100,000 people! Despite the best efforts of hospital infection control personnel using modern monitoring techniques, hand hygiene compliance is still just under 50%.

The purpose of this hand washing exercise is to demonstrate how a microbe passes from one person to another, and how hand washing can reduce the transmission of microorganisms.

The U.S. Centers for Disease Control (CDC) has issued hand washing recommendations to reduce disease transmission in public settings:

  1. Hand washing facilities must be:
    1. Accessible and sufficient
    2. Conveniently located
    3. Provide running water (preferably hot water)
    4. Be designed so that both hands are free during the wash process
    5. Be routinely restocked and cleaned
  2. Hand washing recommendations:
    1. Hands should be wet with running water.
    2. Liquid soap should be provided.
    3. Hands must be vigorously rubbed together for 20 – 30 seconds.
    4. Hands must be rinsed well.
    5. Faucets should shut off by themselves (or by using a paper towel).
    6. Hands should be dried with a disposable paper towel.
    7. This towel should be used to open any door after the process to depart the area.

The use of alcohol-based sanitizers post-washing is also recommended prior to returning to any activity where there may be human to human contact.  In addition, the effectiveness of hand hygiene can be reduced by the type and length of fingernails. There is less evidence that jewelry is a factor in microbial transmission with the exception of ring-wearing.

Microorganisms recovered from the hands can be categorized into two groups:

  1. Resident microorganisms are part of our normal flora and are beneficial to us.  These include:
    1. Staphylococcus aureus
    2. Corynebacteria
    3. Pityrosporum fungi
  2. Transient microorganisms are established via contact with contaminated surfaces. These include a wide variety of microorganisms, dependent upon the lifestyle / work environment of an individual.  These may include, but are not limited to:
    1. Methycillin Resistant Staphylococcus aureus (MRSA)
    2. Vancomycin Resistant Enterococci (VRE)
    3. Clostridium difficile (C. diff)
    4. Listeria monocytogenes
    5. Salmonella spp

In this exercise, we will use a resident microorganism to facilitate the study.  It will also utilize TSA/RB dipslides, which can support the growth of a variety of microorganisms in order to allow for a non-selective environment.

Materials:

TSA/RB Dipslides

Hand washing stations

Bar of soap and liquid soap

Hand sanitizer gel or foam

Procedure:

  1. Create a control:
    1. Without washing your hands, touch your palms and fingertips to each side of a dipslide. Label the vial “control”.
  2. Create a test sample:
    1. Follow the CDC Guidelines for handwashing carefully, then touch your palms and fingertips to each side of a dipslide. Label the vial “clean”.
  3. Create a test sample(s) with variation:
    1. Break the CDC guidelines in one or more ways, then touch your palms and fingertips to each side of a dipslide. Label the vial “variation” or “variation 1”, “variation 2”, etc. if you are doing more than one variation sample.
      1. Examples of variations include:
        1. Use bar soap vs. liquid soap
        2. Vary the type of liquid soap
        3. Use more than one sanitizer (sequentially) during the handwashing
        4. Shorten time of handwashing
        5. Vary the rinse period
        6. Turn off water stream with cleaned hands
        7. Dry your hands on your clothing
        8. Touch an inanimate object (fomite) post handwashing
        9. Shake hands with someone post handwashing
  1. Document the results in a table, similar to the example below. Be sure to record whether there was small, medium, or high amounts of growth, and record the organism descriptions. Use LaMotte’s BioPaddle app to see if you can identify the organisms growing on your paddles.
Dipslide TSA Growth Description TSA Growth

(+, ++, or +++)

RB Growth Description RB Growth

(+, ++, or +++)

Control
Clean
Variation 1
Variation 2

Conclusion

Based on your findings, do you think hand washing is important in preventing the spread of pathogenic organisms? Did the variations in handwashing procedures have significant impact upon contamination of your hands, and subsequently the dipslides?

Increasing hand hygiene compliance will reduce the transmission of microorganisms.  This applies not only to hospitals, but also to schools, restaurants, daycare centers, assisted living facilities, public restrooms, and so on and so forth. In short, be sure to wash your hands properly!