Fomites and Its Risk to Public Health

Everything humans touch is brimming with billions of microbes. People eat at their desks, they put their bags on dining room tables, and they turn doorknobs that hundreds of other hands have touched. These things are done without a second thought, despite the fact that 80% of infections are spread via human hands. (1) The bulk of the microbes one picks up are harmless, but this still means one comes into contact with a vast number of pathogens every day, residing in seemingly innocuous places. These inanimate surfaces that serve as microbial carriers are known as fomites. There has been research done to show that fomites pose a sizeable risk to public health, as infectious levels of pathogenic microbes can easily spread from surfaces to hands to lips, eventually infecting humans. Most of the work done with fomites has been with non-porous, hard surfaces, as these have been proven to be more hospitable to microbes.

This experiment focuses on a bacterium isolated form a fabric backpack belonging to a student at Emory University. Though fabric is porous and therefore less likely to transfer microbes, handbags still have a considerable amount of success as fomites due both to their tendency to come into contact with non-porous bacteria-laden surfaces and their lack of regular sanitization. In an experiment done among healthcare workers in a hospital in Israel, 41. 5% of samples collected from handbags produced positive cultures of bacteria. Of all samples, 4. 6% were pathogenic bacteria while 36. 9% were commensal or environmental bacteria. There has also been some investigation that suggests synthetic fabric wallets showed higher “mean colony-forming units” than wallets made from natural fabric.

The backpack used in the following experiment is synthetic fabric and is used much like a handbag, so there is a high probability that the sample taken will yield bacterial colonies, though perhaps not pathogenic ones. Though the microbe eventually identified may not pose any risk for infection, it is still worthwhile to study and work to assess the physiological properties of the bacterium. Should the unknown bacterium have similar properties to a pathogen, its presence on the backpack suggests the potential growth and transmission of infectious agents. The study of fomites and the microbes they carry matters for more than just intellectual curiosity. Based on a recent study done in Bangladesh, the microbe carrying capacities of cellular phones have led to an increase in antimicrobial resistant bacteria in hospitals, posing major risks to public health.

As the burden of multi-drug resistance grows, it becomes increasingly crucial to identify factors that contribute to the growth and spread of these bacteria. If common fomites can be identified, a conscious effort can be made to sanitize these items and to increase personal hand-washing after touching them. This experiment will serve to assess whether a fabric backpack can serve as a fomite and, if so, what physiological properties a bacterium taken from this environment has.

Methods

Obtaining a Sample

The bottom of a personal backpack belonging to an Emory University student was swapped with a sterile applicator and streaked on to a petri dish containing nutrient agar. Sample was incubated upside down at room temperature for one week. Streaking for IsolationA colony was selected from the sample plate and streaked onto a new nutrient agar plate using proper streaking for isolation protocol.

Plate was incubated for a week at room temperature. After incubation, a colony was selected and was re-plated for isolation on a new nutrient agar plate and incubated at room temperature for a week. This repeated every week throughout the extent of the experiment – eight weeks.

Gram Staining

Bacterium was Gram stained. Three slides, each spotted with a positive control, negative control, and unknown sample, were prepared and fixed. A single slide was flooded with crystal violet for one minute, washed, flooded with Gram’s Iodine for one minute, and then washed again. Two drops of decolorizer were added to each spot, and the slide was washed again. The slide was flooded with safranin for one minute, washed for a final time, and then blotted with a paper towel. Stained spots were observed using an Olympus CX41 microscope and were identified as being Gram positive or negative. If any samples could not be identified, gram stain protocol was repeated using one of the extra slides prepared.