EXPERIMENT. Fomite Transmission. Hands-On Labs, Inc. Version

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1 EXPERIMENT Fomite Transmission Hands-On Labs, Inc. Version Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise. Experiment Summary: You will define the terms infectious disease and pathogen. You will discuss direct and indirect transmission of disease and explain the significance of fomite transmission to the spread of contagion. You will culture samples collected from surfaces in your home and observe for colony development. You will relate experimental results to potential fomite sources within your home. 1 Hands-On Labs, Inc.

2 Objectives Upon completion of this laboratory, you will be able to: Define infectious disease and pathogen. Discuss direct and indirect transmission of disease. Explain fomite transmission. Culture microbes collected from household surfaces. Relate experimental results to potential fomite sources within your home. Time Allocation: 3 hours + 48 hours incubation 2 Hands-On Labs, Inc.

3 Materials Student Supplied Materials Quantity Item Description 1 Bleach 1 Camera, digital or smartphone 1 Coffee mug 1 Distilled water 1 Hand soap 1 Isopropyl alcohol (rubbing) 1 Large cooking pot (at least 8 deep) 1 Oven mitt 1 Permanent marker 1 Roll of paper towels 1 Source of tap water 1 Stove HOL Supplied Materials Quantity Item Description 1 Apron 1 Face mask with ear loops 1 Nutrient agar-18 ml tube 2 Pairs of gloves 2 Petri dish 1 Safety goggles 4 Sterile swabs (2 per pack) 1 Test tube clamp 1 Test tube rack, 6 x 21 mm Note: To fully and accurately complete all lab exercises, you will need access to: 1. A computer to upload digital camera images. 2. Basic photo editing software, such as Microsoft Word or PowerPoint, to add labels, leader lines, or text to digital photos. 3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources. Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit. 3 Hands-On Labs, Inc.

4 Background Disease and Pathogens A disease is defined as a disruption of the normal state of an animal or plant that impairs bodily structure or function. Diseases are often, but not always, accompanied by distinguishing signs and symptoms. The term disease encompasses all ailments and sicknesses that are not related to an accident or natural aging. Diseases can have short or long durations, lasting from hours to years. Examples of diseases include the common cold, cancer, and diabetes. Infectious diseases are caused by microscopic agents called pathogens. Viruses, bacteria, parasites, and fungi are examples of pathogens. See Figure 1 for an illustration of a virus. Infectious diseases that result from the transmission of pathogens from person to person are called contagious diseases. Figure 1. Influenza virus. Centers for Disease Control and Prevention Transmission of Contagious Disease Modes of transmission for contagious diseases include direct transmission and indirect transmission. Direct transmission occurs when a pathogen is passed immediately from one person to another via direct contact, such as a hand shake or by kissing. Indirect transmission involves one of the following intermediate steps: The pathogen is transferred to a fomite, a non-moving object such as a door knob, tissue, or used needle. The pathogen becomes airborne via water droplets produced by coughing or sneezing. The pathogen is transported by a vector such as a living animal or insect. The mode of transmission depends upon the type pathogen (virus, bacteria, etc.). Many pathogens are contracted when an individual touches a fomite such as a handrail, and then touches their mouth, nose, or eye. 4 Hands-On Labs, Inc.

5 The spread of contagions may be reduced by regularly washing hands, disinfecting shared spaces, refraining from sharing personal items (for example, toothbrushes and drinks), covering coughs and sneezes, and avoiding contact with those who are sick. Contagions transmitted through sexual contact may be reduced by using condoms and limiting the number of partners. Improper handling and storage of food items are preventable causes of foodborne contagions. The 2014 Ebola epidemic was the largest in history affecting over 21,000 individuals in multiple countries in West Africa. The Ebola virus, see Figure 2, is spread to humans by direct contact with blood or body fluids from a contaminated individual. Ebola is not spread through the air, by water, or in general by food. Figure 2. Ebola virus attacking a white blood cell. Crevis 5 Hands-On Labs, Inc.

6 Fomites within the Household Environment Numerous objects within the household environment may serve as fomites. Common examples of household fomites include, but are not limited to, countertops, doorknobs, utensils, clothing, and toothbrushes. See Figure 3. Controlling the spread of contagion within the home requires the identification of potential fomites. Once identified, these surfaces can be treated with disinfectants to reduce the number of pathogens they harbor. In this laboratory you will collect and culture microbes from surfaces within your home in order to identify potential fomites. Figure 3. Toothbrushes and countertops can serve as fomites. Blinka 6 Hands-On Labs, Inc.

7 Exercise 1: Fomite Transmission In this laboratory you will incubate microbes collected from 8 household surfaces. After incubation you will compare the number and types of microbes that develop from each surface and relate the results to potential sites of disease transmission within your home. Part 1 of 2 1. Approximately 1 hour before you begin this exercise, pour 2 agar plates. Refer to the appendix entitled Pouring Agar Plates for guidance with this procedure. Note: Plates may be poured in advance, stored in an airtight bag, and refrigerated for future use. 2. Clear a work area and gather all materials listed for this experiment. 3. Wash your hands thoroughly with soap and warm water. 4. Put on the safety gloves, face mask, apron, and goggles. 5. Disinfect the work surface by wiping it with a 10% bleach solution. 6. Using the permanent marker, divide the bottom of each agar plate into 4 sections. Label the sections 1-8. See Figure 4. Figure 4. Labeled agar plates. 7. Identify 8 surfaces within your home that could serve as fomites. Assign each location a number and record the location that corresponds to each number in Data Table 1 of your Laboratory Report Assistant. 8. Remove a sterile swab from the packet and moisten it with distilled water. 9. Rub the moistened swab on surface # Transfer the sample from surface #1 to section #1 of the agar plate by rubbing the swab on the agar surface within the section until it is completely coated with inoculant. Note: Be careful to only inoculate the surface within the outlined section. 11. Place the used swab in a container of undiluted bleach. 7 Hands-On Labs, Inc.

8 12. Repeat steps 8-11 for the each of the remaining agar sections. 13. Place the inoculated plates bottom-side up (inverted) in your incubation location and allow them to incubate for 48 hours. 14. Formulate a hypothesis as to which surface will harbor greatest diversity and total number of colonies. Record your hypothesis in Data Table 2 of your Laboratory Report Assistant. 15. Dispose of the used and bleached swabs in the garbage. 16. Wipe down your work area with bleach. 17. Wash and return items to your kit for future use. 18. Wash your hands thoroughly with soap and warm water. Part 2 of Observe the culture plates after 48 hours for microbial growth. If no colonies are observed, incubate for an additional 24 hours. Note: Avoid removing the lids of the plates when observing. Microbe cultures should always remain covered. 20. Wipe down your work area with a 10% bleach solution. 21. Wash your hands thoroughly with soap and warm water. 22. Put on your goggles, a new pair of gloves, face mask, and apron. 23. Gather the 2 agar plates that have incubated for at least 48 hours. 24. Observe each of the sections without removing the lid. 25. Count the number of different colony types present in each section and record these numbers in Data Table Count the total number of colonies in each section and record the number in Data Table Take a photograph of your incubated plates. Resize and insert the image in to Data Table 3 of your Laboratory Report Assistant. Refer to the appendix entitled Resizing an Image for guidance with resizing an image. 28. Soak the cultured plates in undiluted bleach for 1 hour before disposal. 29. Wipe down your work area with a 10% bleach solution. 30. Wash your hands thoroughly with soap and warm water. 8 Hands-On Labs, Inc.

9 Questions A. What is an infectious disease? What is the role of a pathogen in the spread of disease? B. How does indirect transmission of disease differ from direct transmission? C. How do fomites contribute to the spread of disease? D. Based on the results recorded in Data Table 1, which tested surface is most likely to harbor pathogens? Does this conform to your hypothesis? E. How will the results of this experiment influence how you treat or disinfect tested surfaces in your home? 9 Hands-On Labs, Inc.