Norwex Microfiber Rag Antimicrobial Cleaning Capabilities on Different Surfaces

D. Belnap, S. Lindsay

Introduction

The Norwex® Corporation was established in Norway in 1994 under the name Eidsvoll Miljoprodukter. The company’s focus is on cleaning without chemicals. The company’s moniker is “improving quality of life by radically reducing the use of chemicals in personal care and cleaning” (3). In 2007 the company came out with microfiber rags infused with microsilver. The company’s website states that:

“At only 1/200th the size of a strand of human hair, Norwex Microfiber is one of the most innovative products in the cleaning industry today. When combined with the unique Norwex knitting process, Norwex Microfiber becomes a highly effective cleaning agent and can hold up to seven times its weight in matter. Unlike cotton cloths that will simply spread the dirt, grease and other particles around, Norwex Antibac* Microfiber lifts these particles up into the cloth and away from the surface. Once inside the cloth, the Norwex MicroSilver in the cloth goes to work with self-purification properties against mold, fungi and bacterial odor within 24 hours, so that it is ready to use again”(4).

There are many demonstrations on social media websites, not affiliated with the company, where the Norwex rag is being used in the kitchen to clean. These are personal demonstrations by Norwex employees trying to sell their product. Demonstrations range from cleaning up common spills to wiping down a counter after spreading raw meat on its surface (1). The Norwex rag is shown picking up all the protein on the countertop left from the raw meat; however, there is no discussion of the microorganisms that have contaminated the countertop (i.e. Salmonella enteritidis, Campylobacter jejuni, Listeria monocytogenes). There is also no comparison of other cleaning products to prove that Norwex is the best choice for cleaning in such a situation. The company’s website does not show comparisons of its product versus other products either. This leaves consumers to question whether the Norwex Antibac Microfiber rag is the best product for them and what they want to use it for. In our experiment the Norwex Antibac Microfiber rag was tested against Clorox Disinfecting Wipes and everyday paper towels to see which, if any, disinfects surfaces contaminated with: Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus, or Streptococcus pyogenes.

Materials and Methods

Organisms

Five organisms were selected to be tested against the three cleaning procedures. The basis for their selection was on their cell wall structure and their ability to infect humans. Three gram negative bacteria and two gram positive bacteria were tested.

Salmonella enteritidis (S. enteritidis) is a gram negative rod shaped bacterium. S. enteritidis was selected because it is found on poultry and can be transmitted to humans from contaminated surfaces and cause infection.

Staphylococcus aureus (S. aureus) is a gram positive cocci shaped bacterium. S. aureus was chosen because of its ability to infect human tissue and create pus pockets. The pus from these pockets and the bacteria contained within can be transmitted onto surfaces.

Streptococcus pyogenes (S. pyogenes) is a gram positive bacterium. S. pyogenes was selected because of its pathogenesis to humans. S. pyogenes may cause mild infections of the skin or even pharyngitis. It also may cause potentially life threatening illnesses such as toxic shock syndrome.

Pseudomonas aeruginosa (P. aeruginosa) is a gram negative coccobacillus shaped organism. P. aeruginosa was selected because it can cause disease and is commonly found in water, on skin, and many other environments that humans come into contact with frequently.

Escherichia coli (E. coli) is a gram negative rod shaped bacterium. E. Coli was selected because of its association with the human intestines. E. coli causes illnesses such as gastroenteritis.

Media

Tryptic Soy Agar (TSA) is a medium on which every organism being tested can grow. RODAC (Replicate Organism Detection and Counting) plates were used with TSA for this experiment. The RODAC plates allowed the media to be directly inoculated from the surface being tested, because the agar solidifies above the plastic rim of the plate and can be pressed flat onto surfaces.

Dilutions

Dilutions were done using 9mL blanks and each organism was diluted down to 10-6. Dilutions were then plated onto Tryptic Soy Agar (TSA) and grown at 37°C for 24 hours. This allowed time for the colonies to grow and be counted. Plates that contained between 30 to 300 colonies were retained to indicate which dilution to use for inoculations. The dilutions used were 10-5 for S. pyogenes, 10-5 for S. aureus, and 10-4 for E. coli, P. aeruginosa, S. enteritidis. These dilutions along with their respective colony forming units (cfu) count on the plates gave cfu/mL counts of the original suspensions. It also gave a countable number of cfu’s that the surfaces were inoculated with. Desired solutions were used to contaminate each surface to be tested by placing 0.1mL of the desired dilution/organism on the surface and spreading it around using a sterile hockey stick.

Cleaning techniques

All surfaces were thoroughly cleaned with Spirit II by Zep before testing and all instructions were followed on product label to ensure disinfected surfaces. Disinfected surfaces were tested using RODAC plates to ensure clean surfaces for the experiment. No cfu growth was seen on any of these plates after disinfection.

The Norwex rag was used wet (for cleaning), and directions from the company’s website were used for this experiment. Their instructions state: “1: Fold the cloth in half. 2: Fold it again. You now have a total of eight clean sides to work with. 3: Place your whole hand on the cloth and wipe with even strokes. The cloth should be flat against the surface to be cleaned”(5). The cleaning of each surface was done the same way with each cleaning product (paper towel, Clorox wipe, Norwex rag), namely, five swipes in a clockwise motion with medium pressure. Surfaces were allowed to air dry before being tested for remaining microorganisms.

The method used for cleaning the surfaces with Clorox wipes and paper towels was the same as that used for the Norwex rag. Paper towels, however; were used dry, not wet. Paper towels were tripled up to allow for maximum absorption.

Surfaces tested

Different cleaning products may work better on different surface types. For this reason three different types of surfaces were selected to be tested. Countertop, a horizontal pane of glass, and wood seat bottoms were each chosen as surfaces for this experiment. The countertop was selected because it is semi-porous and not perfectly smooth. The glass was selected because it is non-porous. The wooden seat bottoms, which had no finish on them, were selected because they are porous.

Statistical analysis

A one-way ANOVA (Analysis of Variance) test was performed using Vassarstats online calculator to determine if there was a significant difference between the mean microbial growth of each cleaning product and their respective surfaces

Tukey HSD (Honest Significant Difference) test was performed using Vassarstats online calculator, along with the ANOVA test, to see between which cleaning products the significant differences occurred.

Results

ANOVA tests run comparing each cleaning product against each other on each respective surface showed that there was a significant difference (p<0.05) in the cleaning abilities, of microorganisms, of the three products in this experiment. Clorox wipes and paper towels did not

have a significant difference between them on any surface tested. Norwex Antibac rags on the other hand did have a significant difference between their cleaning abilities compared to both Clorox wipes and paper towels. This significant difference was greater on glass surfaces but

also markedly significant on countertops and chair seats (Table 1). Graphs of average cfu's on the RODAC plates show visually the difference of microorganisms left on each surface tested by each individual product (Graphs 1-3).

Pictures were taken comparing RODAC plates from different surfaces to further show difference in growth after cleaning with each product. It can be seen that there are several different microorganisms growing on each plate that was inoculated from surfaces after cleaning with Norwex Antibac rags. Some cfu’s can also be seen on plates inoculated from surfaces cleaned by paper towels and Clorox wipes. As can be seen however, these cfu’s are few and far between compared to the consistency of numerous cfu’s on every Norwex plate (Figures 1-3).

Table 1: Analysis of Variance (ANOVA) test run to determine significant difference. Tukey HSD (Honest Significant Difference) test was run to narrow down where significant difference occurred among cleaning products. Significant difference if p<0.05.

ANOVA Summary

Countertop Chair Seat Glass

α=0.05 p=0.000328 p=0.000299 p<.0001

Tukey HSD test Norwex vs Clorox p<0.01

Norwex vs Clorox p<0.01

Norwex vs Clorox p<0.01

Norwex vs Paper towel p<0.01

Norwex vs Paper towel p<0.01

Norwex vs Paper towel p<0.01

Clorox vs Paper towel p>0.05

Clorox vs Paper towel p>0.05

Clorox vs Paper towel p>0.05

Graph 1: Average growth of microorganisms on countertops after cleaning with each product.

Graph 2: Average growth of microorganisms on chair seats after cleaning with each product.

Graph 3: Average growth of microorganisms on glass after cleaning with each product.

Figure 1: Each spot on plate is a cfu left on contaminated surface after cleaning. All plates are samples of glass surface. Sal=S. enteritidis. Pa=P. aeruginosa. Ec=E. coli. Sa=S. aureus. Sp=S. pyogenes. Control=before contamination.

Figure 2: Each spot on plates is a cfu left on contaminated surface after cleaning. All plates are samples of chair surface. Sal=S. enteritidis. Pa=P. aeruginosa. Ec=E. coli. Sa=S. aureus. Sp=S. pyogenes. Control=before contamination.

.

Figure 3: Each spot on plates is a cfu left on contaminated surface after cleaning. All plates are samples of Countertop surface. Sal=S. enteritidis. Pa=P. aeruginosa. Ec=E. coli. Sa=S. aureus. Sp=S. pyogenes. Control=before

contamination

Discussion

On the Norwex company website they mention that the fibers of their rag are about 1/200th the size of a human hair (5 μm). This is also about the size of many microorganisms. E. coli for example is 2.0 micrometers (am) long, 0.25-1.0 μm in diameter, and shaped like a rod (2). This means that the Norwex rag may pick it up depending on how it is oriented on a surface or it may not. Also, once in the rag its orientation can change allowing it to fall out of the rag. This means that E. coli could be picked up from one surface and then dropped from the rag on a different surface, thereby spreading the E. coli.

Clorox wipes were used as they would be at home; however, surfaces were allowed to air dry after being wiped with Clorox. This process took approximately 3 minutes. The surfaces did not remain wet for 5 minutes as per instructions on container, therefore; 99.99% of all microorganisms were not killed. Because of this, surfaces tested with RODAC after evaporation showed a few plates that had some cfu’s growing on them. Overall there still were not enough cfu’s on any plate from any surface to be of significance.

Paper towels surprisingly cleaned just as well as Clorox wipes. This can probably be attributed

to the fact that paper towels absorbed the inoculum completely, leaving the surface dry and clean. Absorption properties could possibly affect this. If for example a cheap paper towel were to be used that does not absorb or hold moisture well, more fluid may be left on the surface that contains contaminants. Paper towels would need to be further tested on dry contaminated surfaces to see how they compare to Clorox wipes. Our assumption is that Clorox would outperform paper towels on these dry surfaces.

It did not matter which microorganism was used to inoculate the different surfaces, all tests showed that Norwex Antibac rags were not effective at cleaning any of them. Paper towels and

Clorox wipes were effective at cleaning all three surfaces, and cleaned all microorganisms from the surfaces to the same extent.

Conclusion

On each surface that was tested it was confirmed that not only did the Norwex Antibac rag do the worst job cleaning up the inoculum, it also contaminated every surface tested with other microorganisms that were not the control organism. This means that Norwex would not be the best choice of cleaning products to sterilize contaminated surfaces. Clorox wipes or paper towels are a better choice on any tested surface and with any tested microorganism.

Works Cited

1. AstridsNorwex. Pick Up Everything From Your Surfaces With Norwex Microfiber-Raw Chicken Demo. 2012. Cleaning Arts Channel. Dec 2013. <http://www.youtube.com/watch?v=A6GLGt3NGbE>

2. Escherichia coli. Dec 7, 2013. Dec 2013 <http://en.wikipedia.org/wiki/Escherichia_coli>

3. Norwex: Improving Quality of Life. 2013. Dec 2013 <http://www.norwex.biz/pws/home2999999/tabs/our-purpose.aspx>

4. Norwex: Improving Quality of Life. 2013. Dec 2013 <http://www.norwex.biz/pws/home2999999/tabs/microfiber.aspx>

5. Norwex: Improving Quality of Life. 2013. Dec 2013 <http://www.norwex.biz/pws/home2999999/tabs/microfiber.aspx>