of washing machines , routine environmental disinfection , and the physical separation of areas for clean and dirty linen ) which is not possible with domestic laundering . The lack of control and monitoring associated with domestic laundering , and the lack of compliance with domestic laundering policies ( Riley , Laird , et al ., 2015 ) poses the risk of undetected inadequate decontamination and cross contamination to both the domestic and clinical environments ( Riley , et al ., 2017 ). Indeed , outbreak case studies have indicated the transmission of infection by contaminated domestic washing machines ( Wright , et al ., 2012 ). In-house or industrial laundering of healthcare worker uniforms would mitigate this risk due to implementation of process controls and microbiologically validated wash cycles .”
Soft Surfaces : The Overlooked Vector ?
Owen and Laird ( 2020 ) assert that , “ There is a paucity of studies investigating the role of soft surfaces and healthcare textiles in the transfer of microorganisms or HAI acquisition , despite work demonstrating that they readily become contaminated with microorganisms ( Heudorf , et al ., 2017 ). It is currently assumed that the risk of infection from textiles is low , and there is less emphasis on the decontamination of textiles compared to non-porous surfaces ( Loveday , et al ., 2007 ; Fijan and Turk , 2012 ; Mitchell , et al ., 2015 ).”
Recent studies have demonstrated the survival of potential pathogens on textiles during both domestic and industrial laundering ( Heudorf , et al ., 2017 ; Riley , et al ., 2017 ; Tarrant , et al ., 2018 ), indicating that further studies are warranted to investigate the infection risk associated with contaminated linen .
As McLaren , et al . ( 2019 ) note , “ The role of porous surfaces ( such as healthcare textiles [ HCTs ]) as reservoirs of microbial contamination enabling patient-to-patient transmission of infection is assumed , but not well defined . A recent epidemiologic review of infectious disease outbreaks in hospitals that were attributed to a variety of laundered , clean HCTs did not find confirmed reports of patient-to-patient transmission , but instead revealed that patients in these outbreaks were exposed to environmental bacteria or fungi . Nevertheless , when clean HCTs are put into use during the patient ’ s hospitalization , these porous materials will acquire microorganisms from the patient ’ s skin , contact with potentially infectious body substances , the environment , and from hand transfer of microorganisms by healthcare professionals , visitors , etc . Microbial bioburden on HCTs can vary from < 1 log10 to 4-6 log10 colony-forming units ( CFU )/ 100-cm2 area , depending on the amount of soilage and infectious body substances .”
The Concept of Hygienically Clean
While sterility is the goal in the processing of surgical instruments to prevent infections , the objective in the processing of healthcare textiles is to achieve a status of being considered “ hygienically clean ,” which is an emphasis on soil and bio-material removal according to rigorous standards established by industry organizations that govern these processes . Hygienically clean is defined as being free of pathogens in sufficient numbers to cause human illness , according to the American National Standards Institute ( ANSI )/ Association for the Advancement of Medical Instrumentation ( AAMI ).
As McLaren , et al . ( 2019 ) acknowledge , “ Research conducted by the healthcare laundry industry to determine process parameters for the production of hygienically clean HCTs is increasing . A driving factor in this trend has been the need to evaluate the ability of modern laundry technology to remove soil and inactivate microbial contaminants .” ( Honisch , et al . 2014 )
“ When textiles are considered as hygienically clean , it means that laundry processes , including wash formulas and subsequent handling , have been proven to effectively prevent the transmission of pathogens to protect clinical users ,” says Ben Mead , managing director of Hohenstein Institute America , which researches the human-textile-environment interaction in real-world situations , as well as conducts testing and offers certification of textiles . “ The appropriate levels for HCTs have been set by the German Robert Koch Institute for Public Health after scientific studies on transmission pathways and rates of infection . For an HCT to be claimed as hygienically clean , the textiles , laundry and handling process should be thoroughly monitored . This normally means annual inspections of the laundry processes along with testing of surfaces that can re-contaminate properly laundered textiles . Of course , the most important metric would be the assurance that the textiles delivered to the clinical end user meet the science based limit values and this can be confirmed through objective selection and testing by independent third parties .”
Microbiological testing of clean HCTs for ‘ hygienically clean certification ’ purposes has been introduced to the United States by several entities . As Sehulster ( 2015 ) explains , “ The basic testing program consists of four phases : ( 1 ) initial qualification ( two garments tested ); ( 2 ) probationary period ( six different textiles tested in three months ); ( 3 ) quarterly quality control testing ( testing 28 textiles over three years ); and ( 4 ) onsite sampling ( two textiles tested in each of three years ). This program adopts the pass / fail benchmark of less than or equal to 20 colony-forming units / 100 cm2 total aerobic microbial count on fabric ( similar to the German test benchmark ) using quarterly RODAC testing . Additional textile samples are required to be tested if a laundry ’ s test results exceed the benchmark or if there are changes in the parameters of the laundry processes . Target microorganism testing using the US Pharmacopeia USP < 62 > Microbiological Examination of Nonsterile Products : Tests for Specific Microorganisms is conducted semiannually to detect S . aureus , P . aeruginosa , and E . coli .”
There is some disagreement over the need for testing , with some pointing to the relatively small worldwide number of laundry-related HAIs — approximately 12 over a span of 43 years ( 1970s-2013 ), as cited by Sehulster ( 2015 ), accounting for 350 patients . From 2013 to 2018 , two additional laundry-related HAI reports were published , accounting for a total of 10 patients . This low incidence rate may have influenced the Centers for Disease Control and Prevention ( CDC )’ s decision to not recommend routine microbiological testing of nonporous environmental surfaces or of healthcare textiles for infection control purposes .
As Sehulster ( 2015 ) acknowledges , “ Currently , there is no public health consensus regarding a microbial benchmark to define hygienically clean for textiles . Most importantly , given the historical record for patient safety and extremely infrequent episodes of infection attributed to clean HCTs , the need to establish a certification program based on microbiological testing does not appear to be supported by epidemiologic data . The testing of clean HCTs appears to be a test of a ‘ finished ’ product . Currently in U . S . healthcare , the only finished product testing that is recommended by the CDC is the routine testing of water and dialysate in dialysis settings … The benchmark set for clean HCTs testing does not appear to be linked to patient outcomes , nor is there any indication from the certification program literature that the benchmark is statistically valid ( i . e ., within 90 percent to 99