Biofilm in Commercial Laundries

Biofilm in Commercial Laundries

The focus of ensuring that linens being used by patients and health care providers is free of pathogens and bacteria has been a longstanding principle of infection control groups, commercial laundries, and independent organizations. These groups work to make sure that linen is not a source of Hospital Acquired Infections. Professionally certified laundries that service hospitals and medical clinics operate by a strict set of standards and follow universally recognized practices to ensure that the linens are clean and pathogen free. Independent organizations created plans to protect the integrity of the processes and controls that healthcare laundries who joined would abide by. One unique component that was implemented by the Textile Rental Services Association in its healthcare accreditation program was independent third-party linen testing. Linen testing is broken into two parts; USP 62 which looks for specific pathogens that may lead to hospital-acquired infections and a separate test which aids in the detection of aerobic and anaerobic bacteria that could impact patient safety. Adopting new practices and processes such as the TRSA Hygienically Clean Program allows laundry operators to continue the practice of self-regulation.  It is this type of partnership that ensures textiles are free of pathogens measured by independent linen testing and regular third-party plant inspections.  In fact, there have been no reported instances of pathogens, such as Clostridium difficile on any of the samples submitted over the past five years under the TRSA healthcare program.

Sorting, laundering, and folding seem like simple tasks, but how does one manage those tasks when washing thousands of pounds of soiled linen daily? The key to this is automation. In the early 1960s, laundry equipment manufacturers developed a new technology known as continuous batch washers.  This technology is a series of interconnected modules that move soiled linen through multiple zones to an exit point where it is off loaded and either ironed or dried.   This technology created an economy of scale by reducing the amount of time necessary to process these textiles, and reduced the amount of water, energy and chemical costs incurred by these facilities.   

As the amount of soiled linen continued to increase so did the amount of fresh water being used at these central laundry facilities.  Equipment manufacturers refined tunnel washing technology to further reduce the amount of water, energy, and chemicals used.  As utility and energy costs continued to rise, greater emphasis was placed on developing technology that could further reduce the amount of fresh water being used, as well as developing water reuse systems that could potentially reduce 70% of purchased water.  An unintended consequence of these changes was the increased number of dissolved solids present in both the reuse water and the discharged waste water.  The source of these increased levels of dissolved solids come from calcium, magnesium, soil, and chemicals, and may contain acids that produce dangerously low oxygen levels and very high alkaline compounds, which impacts the waste water leaving the building.  Additionally, these high dissolved contents, if left untreated, create scale on the surfaces inside the tunnel washer and the water recovery systems.

In early 2013 linen testing began under the TRSA Hygienically Clean program.  As the linen testing program was gaining traction in commercial healthcare laundries an abnormal number of samples were failing the aerobic tests, however there was no scientific evidence that could explain the source causing the failures under the RODAC (Replicate Organism Detection and Counting) plate protocol.  Sunburst was contacted by industry leaders to start an aggressive testing program covering laundry plants for each region of the United States in order to identify the source of the problem.  Linen sampling tests commissioned by Sunburst, specifically performing isolate testing on submitted linen samples, identified several non-pathogenic bacteria species.  Based on the results of the isolate tests, Sunburst commissioned a multi-year study to identify what critical elements impacted RODAC plate scores specific to aerobic and anaerobic activity.

To ensure the integrity of the process Sunburst created a single-blind protocol focusing on establishing a base line to identify which elements were causing failures on the RODAC plates. The protocol included testing new unwashed textiles to determine if any pathogens were present before their initial laundering, testing samples prior to drying or ironing, and examining the incoming potable water.  Additionally, we tested a cross section of different equipment manufacturers and water reuse systems.  Focus was also placed on laundry plants that had one process water tank verses plants with tanks for both white linens and colored linens.  This element of the protocol was critical as it demonstrated the negative impact on clarity of the reuse water when only one tank was used. 

At the completion of the five-year study, Sunburst identified that Biofilm formation on the interior and exterior surfaces of the tunnel washing systems, water reuse systems, and process water holding tanks was the source of the elevated colony forming units present on the RODAC plates.

Biofilms and water

The organisms responsible for the creation of biofilms have been around for billions of years and are in the fresh water supply and distribution systems throughout the world. As early as 1930, the American Water Works Association reported the monitoring of bacteria regrowth in potable water systems. By 1937, scientists had discovered bacteria formation in water supply systems that seemed to come out of nowhere. There was no growth at the point of entry, yet microorganisms were multiplying in the distribution pipelines. By the mid-1980s, scientists discovered that the established water and disinfection protocols in effect at the time were inactivating the bacteria in the water supply systems. This meant that the inactive organisms were flourishing and growing exponentially in the pipes and pumping stations used to distribute fresh water to communities.

Recognizing that the organisms would adapt and grow in the distribution pipes and pumps used to move water to consumers, the United States Department of Environmental Protection established the Total Coliform Rule. The Total Coliform Rule became the official rule that water authorities and providers would have to abide by to ensure that potable water was free of disease-causing microorganisms and safe for consumption by the public. It is important to note the EPA did not say biofilms would be or could be eliminated using the method of chlorine disinfection. The EPA recognized that biofilms must be monitored and controlled using chlorine as a treatment protocol because of its effect on decolonizing plumbing systems, tanks, and fresh water supplies.

Biofilm formation on inanimate surfaces

Biofilms are a natural phenomenon which is crucial to why commercial laundry operators need an effective strategy to combat biofilm growth in their facilities. Understanding how this is done begins with recognizing the economy of scale these certified laundries offer the public, particularly in minimizing water and utility usage.  From a global perspective, billions of pounds of soiled linens are processed each year which would not be possible without the use of tunnel washers. The economy of scale that tunnel washers provide by increasing production output, lowering water and gas usage, and reducing wash chemistry is what keeps centralized laundries profitable. Laundry operators continue to seek ways to maximize how soiled goods are laundered, specifically to lessen the impact of rising labor expenses, higher linen replacement costs, reducing utility usage (gas and water), and extending equipment life through regular preventive maintenance. 

Another issue that has impacted commercial laundries is the continual change of the wash chemistry needed to produce clean linens. The prolific use of iodine-based cleansers and disinfectants eliminated the use of chlorine as an inexpensive way to remove stains from soiled textiles. A majority of commercial healthcare laundries use three specific oxidizers to remove stains from dirty laundry; peracetic acid, hydrogen peroxide, and chlorine. Peracetic acid and hydrogen peroxide are widely used for initial laundering, while chlorine is used for final stain processing. As more organic chemical compounds were added to the washing and cleaning process, an increase occurred in the Biochemical Oxygen Demand (BOD) equation in both process water, as well as wastewater discharged from the facilities.

While peracetic acid moves through a plants water recovery system, the chemical oxygen demand increases. In instances where a plant had a codified cleaning plan for the water reuse system, including regular draining of the tunnel washer and process water tanks, the spike of BOD values at the plants discharge to the local sewer authority became problematic. This elemental change to the wastewater profile may result in a facility being placed on watch lists with local wastewater authorities. There is good reasoning behind managing BOD values, as limited oxygen values in wastewater negatively impact the rivers and streams where treated wastewater is discharged. Outside of labor and linen replacement costs, water, and sewer values represent up to 18% of all yearly expenses in a commercial laundry.

As the industry continued to refine ways to lower costs and meet changing customer demands, new manufacturers entered the marketplace with technology to help reuse a portion of the water.  This addition to the water profile inside a laundry plant, specifically reuse values in the 70% range, created an increase in alkalinity values inside the tunnel washers.  A highly alkaline environment inside a tunnel washer can easily create imbalances in the wash chemistry at the front of the tunnel, that requires more organic acids be dispensed to bring down the final pH at the end of the tunnel.  Since a tunnel washer reuses a portion of the rinse water in the wash zone, strong organic acids, such as peracetic acid are mixed with the wash liquor and pumped back from the rinse zone to the wash zone. This requires additional alkaline compounds to be added to the front of the tunnel washer to overcome low pH values created by the use of peracetic acid. In instances where water hardness exceeds 3 grains per gallon and in highly alkaline environment, such as the front compartments of a tunnel washer, scale formation occurs, which is perfect environment for biofilm to thrive. If left untreated the costs can run into the tens of thousands of dollars to remove the scale and biofilm buildup from the front of the tunnel washer.

Intersecting Infection Control with Hygienically Clean Standards

Producing millions of pounds of clean linen each year requires certified laundry facilities to operate under a unified set of standards. Equally, infection control committees, recognize the need for third party verification of both the process used at the laundry facility, as well as the linen being delivered to the hospitals. TRSA requires a “Plant Specific Standards Books” that documents and regulates how a laundry ensures pathogen free textiles are distributed to healthcare consumers. It is more than linen testing; it is a living document that measures, guides, and trains employees on the criteria necessary to continually deliver Hygienically Clean textiles.

Without the linen testing protocol performed under the TRSA Hygienically Clean program, the correlation between biofilm and aerobic activity might not have been discovered. This testing revealed how increased use of reuse water without proper cleaning and disinfection protocols can impact test scores.

Globally recognized baselines for linen testing use two protocols which set the maximum number of Colony Forming Units (CFUs) that are permissible on clean textiles. The Universal Service Protocol or USP 62, combined with testing under the RODAC plate protocol, are the benchmarks used in conjunction with the TRSA Hygienically Clean plan for certified laundries. The USP 62 protocol tests for CFUs of pathogens (such as Staphylococcus aureus or Pseudomonas aeruginosa, which are on the CDC top 10 list).  If one CFU of the tested pathogens is present, it is considered a failure under the USP 62 protocol. Anaerobic and aerobic plate testing has a maximum allowable limit of 20 CFU’s. 

Biofilm Creation in Water Reuse Systems

Since virtually all medical textiles are processed in water, it is critical that any water recovery system include design elements that monitor pH, conductivity, and overall water clarity. The system must include water sampling ports to monitor biofilm formation. If the design of the reuse system only has one tank for storing all processed water, then the overall clarity of the water is diminished due to leaching from laundering colored textiles.   Additionally, this flaw may result (based upon the total amount of reuse water recovered) in color redeposition on processed textiles.

Biofilm Creation on Washing Equipment

 As the overall costs associated with producing clean medical textiles continued to increase, commercial laundry operators found ways to affect these challenges by staging the tunnel washers with dirty goods for next day production. This philosophy was sound until the treatment procedures healthcare providers were using changed, specifically greater use of iodine-based cleansers and disinfectants to improve patient’s healthcare outcomes.  Conversely, this resulted in a significant industry-wide change to the type of bleaches used in commercial laundries, specifically shifting away from chlorine as the primary bleaching agent.  By 2001, most healthcare laundries were forced to convert to chlorine-free washing, yet continued to rely on the strategy of next day production staging.

With chlorine-free washing taking effect, the Environmental Protection Agency ordered modifications to laundry detergents used at these plants.  Because of these changes, biofilm creation became more prolific, yet most operators were unaware of the issue because linen testing was not a requirement. As linen testing became widespread, the correlation between next day linen staging, infrequent equipment cleaning, and failures on RODAC plates became evident. Sunburst identified that biofilm creation produced by these practices was causing failures under the established standard and was asked to create a permanent treatment plan.  The Sunburst treatment protocol focuses on three areas; fresh water, water reuse systems, and process water tanks.   

Final thoughts on biofilms and creating an effective cleaning plan

  • Biofilms are impacted both by the soil goods processed (soil loading of wash liquor), total gallons of fresh water introduced into the system, as well elements that naturally occur in the incoming fresh water.
  • Biofilm creation is a daily and ongoing process. Whether we are referring to fresh water systems or process water found in most commercial laundry operations, biofilm will be formed.
  • Biofilms are bacteria. Their destruction and removal are based on establishing and following your cleaning plan. 
  • Processing stained goods using chlorine in the tunnel is an excellent way to limit biofilm creation; however regular cleaning of the equipment is still required.
  • Biofilm is easily formed, and the most common areas include; all interior surfaces of the tunnel washer, load chutes, water reuse tanks, internal press shuttles, press pans, interior of the press enclosure, weir boxes, process water tanks including flow lifters, flow splitters, pulse flow tanks, surge tanks, drains, interior surfaces, pumps, shaker screens, lids and doors that contain process water in the accompanying tank, and all hoses and pipes that move reuse water.
  • When ordering new tunnels, or water reuse systems, ensure that drains are included in all available modules and tanks to aid in soil and cleaning solution removal.
  • Using steam disinfection in tunnel washers is also an option in lieu of chlorine disinfection. Please consult your specific manufacturer for guidance.
  • Products that have disinfection claims, such as peracetic acid or quaternary sanitizers are only applicable while they are in the washer module. These claims do not extend once they are removed from the washer. These products should not be used for machine cleaning or disinfection as they are not intended for this purpose.

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