Authors: Max Greisberg
Justin Greisberg, MD
Professor of Orthopaedic Surgery, Columbia University
Chief of Foot & Ankle Orthopaedics
Chief of Orthopaedic Trauma
622 W 168th St
PH 11th floor
New York, NY 10032
Fax (212) 305-4024
The authors have no conflicts of interest to disclose.
No funding was received for this research.
Assessment of Disinfection Techniques for Decontaminating Athletic Mats
Skin infections are a hazard in close contact sports. Disinfection of wrestling mats is widely recommended to reduce the incidence of infection, but there is little to no evidence how best to clean the mats. In this study, microorganism levels from the wrestling mats of two schools were quantified to determine if disinfection reduces the bacterial load from the surface of the mats and in the seams between mat sections; and to determine if using a flat mop is more effective than a string mop. This study found that both techniques were effective in reducing the bacterial load of the mats. However, neither method was effective at reducing bacterial counts in the grooves between mat sections. There was a trend favoring the use of a flat mop over a traditional string mop, but the trend did not meet statistical significance. Future research may focus on whether widespread adoption of these techniques leads to a lower incidence of skin infection in athletes.
Keywords: wrestling mat, disinfection, skin infections, cleaning techniques, flat mop, string mop
Skin infections are a hazard in close contact sports, especially wrestling. Among collegiate sports, wrestling has an overall injury rate second to football, but has the largest share of skin infections at 73.6% (1, 2). The prevalence of methicillin-resistant Staphylococcus aureus may be as high as 60.1 per 10,000 wrestlers, and the incidence of serious infections, such as those by methicillin-resistant Staphylococcus aureus, is increasing (1, 3). In addition to athlete hygiene, there is general agreement that disinfection of wrestling mats is an important part of prevention. Despite the consensus, there are little if any standards on how to disinfect the mats. There is even less evidence on which techniques may be the most effective in decreasing the incidence of illness in athletes.
The NCAA (National Collegiate Athletic Association) requires regular disinfection of wrestling mats prior to competition, but does not specify any cleaning technique details (4). The NWCA (National Collegiate Wrestling Association) recommends wiping down the mats with cleaning solution and then clean water to remove any residue (5). The organizations do not specify which disinfectant is optimal. Furthermore, the practice of wiping down the mat before the disinfectant fully dries may decrease the effectiveness of any disinfectant.
There are a surprising number of variables in the assessment of mat disinfection, including disinfecting solution, mop type (string or flat), and location of testing (surface or seams). Athletic mats are modular, with long seams between mat sections. No research has examined the microorganism levels in the seams. Some have proposed that a flat mop may be more effective than a string mop (since bacteria may be able to ‘hide’ in the fibers of the string mop) but this is not proven.
Inherent in any athletic participation is some risk for injury. Acquired skin infections may come as a surprise to most competitors, but can lead to extensive time lost from sport, as well as serious illness. In one study of high school athletes, the highest number of skin infections occurred in wrestling (73.6%), followed by football (17.9%) (1). Most were bacterial (60.6%), with some fungal (tinea) as well. Other studies show that the rate of viral skin infections may pose a hazard as well (9).
Close contact between athletes for an extended period is probably a significant component to the pathology of infection, but the wrestling mats are a potential incubator for pathogens. Many microorganisms have been identified on gym mats, including influenza, ringworm, herpes, and methicillin-resistant Staphylococcus aureus (3, 10). Routine disinfection of wrestling mats is expected to decrease the levels of microorganisms and thus decrease the incidence of acquired skin infection.
Disinfectants can work in different ways. Simply washing the mats with water and/or soap will dilute microorganisms, and wash away a fair number. Adding a bactericidal agent, such as bleach, will further kill bacteria. Some agents claim to have residual activity, so that bacterial killing will continue even after the mats have dried.
Johnston, et al (6) compared the ability of different agents to reduce bacterial growth. “Natural” agents were not very effective at all, while traditional bactericidal products did inhibit growth of Staphylococcus aureus. Young, et al (7) found that bleach, ammonium products, and phenolic products all dramatically reduced bacterial load on mats, but agents with residual activity were better at keeping counts low in the first hours after cleaning. Mats cleaned with bleach showed rapid increase in bacterial levels as soon as athletes returned to them. In another study, agents with residual activity were not more effective at reducing bacterial levels so that there is no clear answer which disinfectant might be best (8).
Furthermore, there are variables in how the disinfectant is applied to the mat surface. A string mop potentially can harbor organisms, especially when it is repeatedly dipped into a bucket of cleaning solution. A flat mop may have less “hiding spaces” for bacteria. Disinfectants need to be given time to dry out for full effectiveness. In general, current recommendations are for disinfectant to be applied directly to the mat surface, and then spread with a flat mop, while the person cleaning works backwards, away from the cleaned surface. The surface is then allowed to dry, without the cleaning person walking on the wet mat (7, 8). In a study comparing cleaning techniques, the use of a flat mop with disinfectant applied directly to the mat was more effective at decreasing bacterial counts than a traditional mopping (8). In this study, microorganism levels from the mats of two different wrestling programs were quantified in order to compare efficacy of disinfection techniques. One school applied disinfectant directly to the mats and spread it with a flat mop. The other used a bucket of the same solution with a traditional wet string mop. We propose that both techniques will reduce microorganism levels. We also propose that the flat mop will be more effective than the string mop. Finally, we propose that neither method will be effective at disinfecting the seams between mat sections.
Microorganism levels from the wrestling mats of two different schools were quantified at different time points and at different locations. To obtain surface samples, sterile swabs were wiped on the mat in a consistent pattern, along six feet of the mat, diagonally across. For the seams between mats, swabs were run along four feet of a seam between mat sections. Samples were taken following two hours of wrestling practice, and then immediately following mat disinfection. Each team had approximately thirty athletes competing on the mats over the course of a session. At each school, mats were sampled on five different days over a two-week period in the wrestling season.
The swabs were then streaked onto agar plates (Carolina Biological, Burlington, NC), with a consistent sterile technique running back and forth five times (the shape of a ‘W’), twirling the swab along the way. Initial pilot studies found that culture growth was abundant at 37 °C, at 48 hours of incubation. Incubation for a shorter period of time, or at room temperature, was less productive.
Forty-eight hours after streaking the culture plates, microorganism levels were quantified. The linear length of the culture streaking that showed growth was divided by the entire length of the streak, to give a percentage of growth. At each time point, 2 swabs were obtained from the surface of the mat at 2 different locations, and one was streaked from a seam between mat sections. Each of the two mats was sampled on five different days, immediately following disinfection and following a practice session. Negative controls (sterile swab) were streaked onto culture plates at every test date, and showed zero percent growth throughout the study.
Both schools used the same disinfectant (Ken Clean Plus, Kennedy Industries). The active ingredients are 2.5% dodecyl dimethyl ammonium chloride and 1.6% dimethyl benzyl ammonium chloride. The manufacturer does not indicate whether this is a disinfectant with residual activity. One school sprayed the solution directly onto the mat, and then used a flat mop to spread it evenly across the surface. The other school used a bucket with cleaning solution and a string mop to apply the disinfectant. The mats were allowed to air dry before samples were taken.
Means of microorganism growth were compared before and after disinfection, as well as between the schools. T-tests were used to determine significance, with p<0.05 set as significant.
The purpose of this study was to determine whether string or flat mop usage and direct or indirect application of disinfectant demonstrated any significant difference in the rate of disinfection of wrestling mats. Samples taken following wrestling practice showed a mean of 72% growth at 1 school, and 77% at the other; these were not statistically different. Following disinfection, the school, which sprayed the mats, down and then wiped with a flat mop showed a mean of 12% growth; this was significantly improved from prior to cleaning. The other school, using a string mop and bucket of the same disinfectant, had 35% growth, which was also significantly different from prior to cleaning. See Table 1. Thus, both disinfection techniques were effective at reducing microorganism levels.
Table 1. Surface of Mats: Mean Level of Micro-organisms
(prior to disinfection)
|After Disinfection||T-Test p-Value|
(Flat mop + direct spray)
|School 1 vs School 2
Following disinfection, the school using the flat mop technique had a greater reduction in microorganism levels compared to the school using the string mop (83% versus 56%), but this did not reach statistical significance. We cannot conclude that a flat mop is superior to a string mop.
Based on initial results of this study, the school, which had used a string mop, changed their protocol to using a flat mop. Even though the results did not reach statistical significance, the change to a flat mop was inexpensive and considered low risk. Following disinfection with a flat mop and direct application of the disinfectant to the mat (not from a bucket of solution), the growth rate dropped to zero on the mat surface.
Samples from the seams (grooves) between mat sections did not show significant improvement with either method of cleaning (69%) mean growth after cleaning, see Table 2. Neither cleaning method was effective at disinfecting the seams.
Table 2. Grooves Between the Mats: Mean Level of Microorganisms
(prior to disinfection)
|After Disinfection||T-Test p-value|
(Flat mop+direct spray)
Despite the relatively high prevalence of acquired skin infections in wrestling, and despite the widespread availability of disinfecting solutions, there are no guidelines as to best practices for cleaning athletic mats. Stehura and Jacobs (8) proposed spraying disinfectant directly to the mat surface and then wiping down with dry towels. They found a reduction of 86% of the bacterial load, compared to only 26% decrease using a traditional cleaning solution and wet mop. Another study found a reduction in bacterial load of 76% with use of residual disinfectants (chemicals which have residual activity even after drying) (7).
This study found that disinfection of wrestling mats does decrease the microorganism load on the surface. The reduction in bacterial load was similar to that found in other studies(7, 8). The technique of directly spraying the disinfectant on the mat and spreading with a flat mop may be more effective than using a string mop and a bucket of disinfecting solution, but this did not reach statistical significance in this study.
Furthermore, when a string mop is repeatedly dunked into a bucket of cleaning solution there may be more opportunity for contamination over the course of a cleaning session.
Regardless of cleaning technique, the seams between mat sections were not effectively decontaminated. This finding has not been previously discussed. It is not clear whether microorganisms in these seams play a part in disease. We recommend taping over grooves between mat sections prior to disinfecting, and keeping the tape in place during athletic participation. This simple intervention may lower bacterial counts on athletes’ skin and possibly lower the incidence of infection.
Disinfection of wrestling mats does decrease the level of microorganisms on the mats. Directly applying disinfectant to the mat and spreading with a flat mop may be more effective than using a bucket of the same cleaning solution with a traditional string mop. The seams between mat sections are not adequately disinfected with current techniques, so taping over these sections may be the best practice. Future research may focus on whether widespread adoption of these techniques leads to a lower incidence of skin infection in athletes.
This study has several weaknesses. The method used to quantify microorganism levels may not be as accurate as other methods, such as serial dilutions. However, the reduction in bacterial load was of similar magnitude to other studies. Beyond the accuracy of the “counting,” the accuracy of environmental sampling (running a swab over a mat) will be subject to error to some degree in any study of this kind. The data is an estimation of the true microorganism levels, but the trends can give useful information.
Furthermore, the cultures could not distinguish serious pathogens from routine environmental flora. While some infections are caused by the serous pathogens like MRSA, others are related to routine flora. The cultures used in this study did not thoroughly screen for fungi, yet these organisms can be important sources of skin infection in athletes. Previous studies have isolated both benign and pathogenic bacteria, fungi, and viruses from wrestling mats (7).
Application to Sport
This research may assist practitioners in the development of decontamination technique guidelines associated with the use of floor mats in sport.
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- Wrestling rules committee. (2017). ‘Item 2 C: Matt safety and hygiene’. In Report of the NCAA Wrestling Rules Committee 10-12 April 2017, NCAA, https://www.ncaa.org/sites/default/files/Apr2017MWR_Rules_Committee_Annual_Meeting_Report_20170918.pdf
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