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Laundering of hospital staff uniforms at home
Journal of Hospital Infection (2006) 62, 89–93
www.elsevierhealth.com/journals/jhin
Laundering of hospital staff uniforms at home S.N. Patel, J. Murray-Leonard, A.P.R. Wilson* Department of Clinical Microbiology, Windeyer Institute of Medical Sciences, University College London Hospital, 46 Cleveland Street, London W1T 4JF, UK Received 18 December 2002; accepted 11 June 2005 Available online 7 October 2005
KEYWORDS Infection control; Domestic laundry; Prevention of infection
Summary Few hospitals now launder staff uniforms. Staff are expected to use their own domestic machines, most of which run with 40 8C cycles. However, there is little information on the effectiveness of home laundering. This study demonstrates that domestic washing machines reduce viable counts of Staphylococcus aureus to below detectable levels from an inoculum of 108–1012 colony-forming units (R106-fold reduction), even using low temperature (40 8C) programmes. Environmental organisms, predominantly Gram-negative flora, were introduced from the machine itself but were destroyed by tumble drying or ironing. Domestic laundering of uniforms is an acceptable alternative to hospital laundering if combined with tumble drying or ironing. Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction Although national guidelines have been published on hospital laundry processes,1 little information is available on home laundering of staff uniforms or clothing. An increasing number of hospitals are encouraging staff to wash their own uniforms and do not provide laundry facilities in the hospital, mostly for reasons of cost. Many staff launder their own uniforms at home for convenience or in the belief that their uniform would be damaged or lost by a hospital laundry. * Corresponding author. Tel.: C44 207 380 9516; fax: C44 207 636 6482. E-mail address: [email protected]
A wide range of organisms can be isolated from soiled clothing including Staphylococcus aureus, Clostridium difficile and vancomycin-resistant enterococci.2 S. aureus is the most important hospital-acquired pathogen and methicillin-resistant S. aureus (MRSA) in particular is used as a marker of cross-infection. The UK Department of Health has recently announced that MRSA bacteraemia should be halved by 2008.3 The efficacy of decontamination of uniforms in domestic washing machines may then be a factor in preventing transmission and possibly infection with MRSA or other staphylococci.4 The aim of this study was to determine the effectiveness of laundering at home on scrub suits and a variety of other fabrics, contaminated with S. aureus at a known inoculum.
0195-6701/$ - see front matter Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2005.06.002
90
S.N. Patel et al.
Methods The University College London Hospital Ethics Committee approved the study.
Preparation of inocula A single colony from an overnight culture of S. aureus NCTC 6571 was suspended in 5 mL nutrient broth (Oxoid Limited, Hampshire, UK) and vortexed for 5 min to distribute the organisms evenly. The concentration of the resulting suspension was determined using a Miles and Misra technique.5 Hospital-laundered scrub suits were cut into ten 5cm squares using sterile scissors. Each square was inoculated over its entire surface with 400 mL broth. The squares were allowed to dry for a minimum of 30 min. For the 40 8C wash, the measured inoculum of S. aureus for each square of cloth was 5.6!108 colony-forming units (cfu). For the 60 8C wash, the inoculum was 2.7!1010 cfu, and the inoculum was 3.4!10 12 cfu for the laundering of different fabrics.
Processing of inoculated fabric The fabric squares were taken individually in sterile containers to a new domestic washing machine that had passed manufacturer’s quality controls on maintenance of wash temperatures. Five squares were laundered together in a 40 8C wash cycle using non-biological washing powder without bleach. The other five squares were washed together in a 60 8C wash cycle with the same powder (Figure 1). They were not placed in a standard load and the procedure was only performed once. One square from each cycle was removed at the end of the cycle and sent to the laboratory. Two squares from
Figure 1
each cycle were air dried and the remaining two squares from each cycle were tumble dried separately for 30 min. The dried squares were then either ironed or not ironed, resulting in one square with each possible combination of washing and drying (Figure 1). The squares were returned to the laboratory in individual sterile containers.
Efficacy of washing in decontamination Two methods were used consecutively on each fabric square to detect the total viable count (TVC) and the remaining bacterial count of S. aureus: (a) each square was pressed firmly on to a blood agar plate using a sterile cotton tip applicator and then removed, following which (b) the entire square was soaked in 5 mL nutrient broth, agitated for 10 min and three separate drops of 20 mL broth were placed on a blood agar plate. All culture plates were incubated overnight at 37 8C in air. The plates were examined for the presence of S. aureus using Gram’s stain appearance, catalase and Staphaurex (Murex Diagnostics Limited, Dartford, UK) tests.
Controls An uninoculated square of material from theatre scrubs was tested directly from the hospital laundry. Another uninoculated single square was tested after being transported in the same way and for the same time at room temperature as the other squares.
Other fabrics and machines To assess whether the type of fabric affected retrieval of organisms, six different types of cloth
Flow chart to show processing of inoculated fabric squares. Two uninoculated squares were used as controls.
Home laundering of uniforms
91
were inoculated with S. aureus and processed in the same way. A wash cycle of 40 8C followed by tumble drying for 30 min was used for all samples to mimic the usual domestic laundering process. Finally, to assess whether contamination was common to other machines, four uninoculated 5!5 cm2 of hospital-laundered theatre scrubs were washed in four different machines using a 60 8C cycle. The fabric squares were not tumble dried or ironed.
Comparison of laundering of different fabrics
Results
Washing uninoculated squares in different machines resulted in contamination with a mixture of coagulase-negative staphylococci, Gram-positive bacilli and Gram-negative bacilli (Table III). Washing machine 2 had automatically been set to tumble dry for 10 min after the wash and contained the fewest number of organisms.
S. aureus was not isolated from any of the fabrics after the washing process (Table II). The environmental organisms isolated were similar to those isolated previously and were found in similar numbers for the different fabrics.
Comparison of different domestic washing machines
The two uninoculated control squares of scrub suit did not show any evidence of S. aureus. However, environmental organisms other than S. aureus were detected. Using the broth detection method, the TVC of the material direct from the laundry was 80 cfu, compared with 680 cfu for the material transported and kept at room temperature for the same time as the other samples.
Discussion
40 8C wash cycle
Several physical and chemical factors are responsible for the removal of microbes by normal laundering processes.6 Organisms are diluted during washing, and soaps and detergents loosen soil and are bactericidal. Heat from the washing machine and from drying and ironing are effective in destroying micro-organisms, and chlorine and rapid changes in pH further reduce contamination. Recent studies have shown that a satisfactory reduction in microbial contamination can be achieved at low temperatures (22–50 8C) when the cycling of the water, wash formula and amount of chlorine are carefully monitored and controlled.7 National Health Service guidelines recommend that linen (defined as all articles for laundering)
S. aureus was not isolated from any square after the wash cycle (Table I). The squares that were removed immediately after the wash cycle before drying showed the greatest number of organisms retrieved, mainly oxidase-positive Gram-negative bacilli. Tumble drying or ironing reduced the TVC and when both were performed sequentially, bacteria were no longer detected.
60 8C wash cycle The 60 8C wash produced similar findings to the 40 8C wash but with a greater reduction in TVC (Table I).
Table I Total viable counts on scrub suit fabric after 40 8C and 60 8C wash cycles determined by both broth and contact methods Procedure
Total viable count (bacterial count of Staphylococcus aureus) from single fabric squares 40 8C wash cycle 60 8C wash cycle Broth (cfu/mL)
Fabric removed after wash cycle WashedCair dried WashedCair driedCironed WashedCtumble dried WashedCtumble driedCironed
O1!10
10
(0)
1.9!109 (0) 50 (0) 330 0 (0)
Contact (cfu)
Broth (cfu/mL)
O1!1010 (0)
210 (0) 4 (0)
4700 (0) 6 (0)
20 (0) 0 (0)
5
66
(0)
0 (0)
10
Contact (cfu)
(0)
O1!10
10
O1!10
0 (0)
Each row represents one fabric square washed at 40 8C and one at 60 8C. cfu, colony-forming units.
7 0 (0)
92 Table II
S.N. Patel et al. Comparison of different fabrics laundered at 40 8C and tumble dried for 30 min: total viable count
Type of material
Total viable count (bacterial count of Staphylococcus aureus) from a single square of each material Broth (cfu/mL) Contact (cfu)
100% polyester—rough texture 100% polyester—smooth texture 100% cotton velvet 100% cotton—T shirt material 55% cottonC45% polyester Wool—blend tweed
1250 (0) 250 (0) 1250 (0) 1250 (0) 750 (0) 1250 (0)
28 15 52 30 78 73
(0) (0) (0) (0) (0) (0)
Each row represents a single square of material. cfu, colony-forming units.
should be divided into three categories: used (soiled and foul), infected and heat-labile. 1 Infected linen is that from patients with or suspected of having a variety of communicable diseases. For used and infected linen, the washing process should have a disinfection cycle in which the temperature in the load is maintained at 65 8C for not less than 10 min or, preferably, at 71 8C for not less than 3 min. Additional time is recommended to allow mixing and heat penetration. Heat-labile linen is likely to be damaged by these temperatures and is processed in a cooler wash with the addition of certain chemicals, e.g. sodium hypochlorite. Recommendations for hospital laundering cannot be applied to the domestic situation. The majority of domestic laundering is at 40 8C or 60 8C followed by tumble drying or ironing, and does not use added chemicals. Unlike commercial machines, the wash load in domestic washing machines is not held at a particular temperature. As soon as the required temperature is achieved, the programme advances and there is no further heating of the water. The temperature gradually decreases as the wash programme continues. This study used a new domestic washing machine that had passed the manufacturer’s quality control with respect to the initial temperature achieved.
Ayliffe and Collins did not recommend home laundering because temperature control was not sufficient to ensure that uniforms were sterile.8 A small study of laundering of uniforms in domestic washing machines concluded that it was safe provided they were washed at not less than 50 8C and then ironed dry with a hot iron.9 The researchers used a contact method for retrieval of organisms from uniforms contaminated with Serratia marcescens. Identification of the organisms retrieved was not attempted. Our results suggest that the contact method was less sensitive than the broth method. All the organisms that were retrieved after the 40 8C and 60 8C wash cycle were derived from the washing machine and not the initial inoculum of S. aureus. Washing was sufficient to remove heavy contamination with S. aureus. However, the washing process itself resulted in contamination of the fabric with a mixture of environmental bacteria. Tumble drying and/or ironing were sufficient to remove these process-related bacteria. The findings were not affected by the type of fabric. Similar observations have been made in hospital-laundered linen.10 The results demonstrate that theatre scrubs or workers’ own clothing can be safely washed at 40 8C if tumble dried for 30 min and/or ironed. Potential pathogens other
Table III Comparison of different washing machines: total viable count from uninoculated squares laundered using 60 8C wash cycle Washing machine 1 2a 3 4
Total viable count from a single square for each machine of each material Broth (cfu/mL) Contact (cfu) 180 1 300 200
A single square of material was tested in each machine. cfu, colony-forming units. a Machine 2 was automatically set to tumble dry for 10 min after washing.
576 6 1584 360
Home laundering of uniforms than S. aureus should now be assessed by these methods.
References 1. Department of Health. Hospital laundry arrangements for used and infected linen. Health service guidelines HSG 95 (18). London: NHS Executive; 1995. 2. Perry C, Marshall R, Jones E. Bacterial contamination of uniforms. J Hosp Infect 2001;48:238—241. 3. Anonymous. Health Secretary announces MRSA target. CDR Wkly 2004;14:3.
93 4. Hedin G. Staphylococcus epidermidis–hospital epidemiology and the detection of methicillin resistance. Scand J Infect Dis Suppl 1993;90:1—59. 5. Miles AA, Misra SS, Irwin JO. The estimation of the bacterial power of the blood. J Hyg 1938;38:732—749. 6. Walter WG, Schillinger JE. Bacterial survival in laundered fabrics. Appl Microbiol 1975;29:368—373. 7. Blaser MJ, Smith PF, Cody HJ, et al. Killing of fabricassociated bacteria in hospital laundry by low-temperature washing. J Infect Dis 1984;149:48—57. 8. Ayliffe GA, Collins B. Laundering of nurses’ dresses at home. J Hosp Infect 1989;13:91. 9. Callagan I. Bacterial contamination of nurses’ uniforms. A study. Nurs Stand 1998;13:37—42. 10. Nicholes PS. Bacteria in laundered fabrics. Am J Public Health Nations Health 1970;60:2175—2180.
www.elsevierhealth.com/journals/jhin
Laundering of hospital staff uniforms at home S.N. Patel, J. Murray-Leonard, A.P.R. Wilson* Department of Clinical Microbiology, Windeyer Institute of Medical Sciences, University College London Hospital, 46 Cleveland Street, London W1T 4JF, UK Received 18 December 2002; accepted 11 June 2005 Available online 7 October 2005
KEYWORDS Infection control; Domestic laundry; Prevention of infection
Summary Few hospitals now launder staff uniforms. Staff are expected to use their own domestic machines, most of which run with 40 8C cycles. However, there is little information on the effectiveness of home laundering. This study demonstrates that domestic washing machines reduce viable counts of Staphylococcus aureus to below detectable levels from an inoculum of 108–1012 colony-forming units (R106-fold reduction), even using low temperature (40 8C) programmes. Environmental organisms, predominantly Gram-negative flora, were introduced from the machine itself but were destroyed by tumble drying or ironing. Domestic laundering of uniforms is an acceptable alternative to hospital laundering if combined with tumble drying or ironing. Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Introduction Although national guidelines have been published on hospital laundry processes,1 little information is available on home laundering of staff uniforms or clothing. An increasing number of hospitals are encouraging staff to wash their own uniforms and do not provide laundry facilities in the hospital, mostly for reasons of cost. Many staff launder their own uniforms at home for convenience or in the belief that their uniform would be damaged or lost by a hospital laundry. * Corresponding author. Tel.: C44 207 380 9516; fax: C44 207 636 6482. E-mail address: [email protected]
A wide range of organisms can be isolated from soiled clothing including Staphylococcus aureus, Clostridium difficile and vancomycin-resistant enterococci.2 S. aureus is the most important hospital-acquired pathogen and methicillin-resistant S. aureus (MRSA) in particular is used as a marker of cross-infection. The UK Department of Health has recently announced that MRSA bacteraemia should be halved by 2008.3 The efficacy of decontamination of uniforms in domestic washing machines may then be a factor in preventing transmission and possibly infection with MRSA or other staphylococci.4 The aim of this study was to determine the effectiveness of laundering at home on scrub suits and a variety of other fabrics, contaminated with S. aureus at a known inoculum.
0195-6701/$ - see front matter Q 2005 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2005.06.002
90
S.N. Patel et al.
Methods The University College London Hospital Ethics Committee approved the study.
Preparation of inocula A single colony from an overnight culture of S. aureus NCTC 6571 was suspended in 5 mL nutrient broth (Oxoid Limited, Hampshire, UK) and vortexed for 5 min to distribute the organisms evenly. The concentration of the resulting suspension was determined using a Miles and Misra technique.5 Hospital-laundered scrub suits were cut into ten 5cm squares using sterile scissors. Each square was inoculated over its entire surface with 400 mL broth. The squares were allowed to dry for a minimum of 30 min. For the 40 8C wash, the measured inoculum of S. aureus for each square of cloth was 5.6!108 colony-forming units (cfu). For the 60 8C wash, the inoculum was 2.7!1010 cfu, and the inoculum was 3.4!10 12 cfu for the laundering of different fabrics.
Processing of inoculated fabric The fabric squares were taken individually in sterile containers to a new domestic washing machine that had passed manufacturer’s quality controls on maintenance of wash temperatures. Five squares were laundered together in a 40 8C wash cycle using non-biological washing powder without bleach. The other five squares were washed together in a 60 8C wash cycle with the same powder (Figure 1). They were not placed in a standard load and the procedure was only performed once. One square from each cycle was removed at the end of the cycle and sent to the laboratory. Two squares from
Figure 1
each cycle were air dried and the remaining two squares from each cycle were tumble dried separately for 30 min. The dried squares were then either ironed or not ironed, resulting in one square with each possible combination of washing and drying (Figure 1). The squares were returned to the laboratory in individual sterile containers.
Efficacy of washing in decontamination Two methods were used consecutively on each fabric square to detect the total viable count (TVC) and the remaining bacterial count of S. aureus: (a) each square was pressed firmly on to a blood agar plate using a sterile cotton tip applicator and then removed, following which (b) the entire square was soaked in 5 mL nutrient broth, agitated for 10 min and three separate drops of 20 mL broth were placed on a blood agar plate. All culture plates were incubated overnight at 37 8C in air. The plates were examined for the presence of S. aureus using Gram’s stain appearance, catalase and Staphaurex (Murex Diagnostics Limited, Dartford, UK) tests.
Controls An uninoculated square of material from theatre scrubs was tested directly from the hospital laundry. Another uninoculated single square was tested after being transported in the same way and for the same time at room temperature as the other squares.
Other fabrics and machines To assess whether the type of fabric affected retrieval of organisms, six different types of cloth
Flow chart to show processing of inoculated fabric squares. Two uninoculated squares were used as controls.
Home laundering of uniforms
91
were inoculated with S. aureus and processed in the same way. A wash cycle of 40 8C followed by tumble drying for 30 min was used for all samples to mimic the usual domestic laundering process. Finally, to assess whether contamination was common to other machines, four uninoculated 5!5 cm2 of hospital-laundered theatre scrubs were washed in four different machines using a 60 8C cycle. The fabric squares were not tumble dried or ironed.
Comparison of laundering of different fabrics
Results
Washing uninoculated squares in different machines resulted in contamination with a mixture of coagulase-negative staphylococci, Gram-positive bacilli and Gram-negative bacilli (Table III). Washing machine 2 had automatically been set to tumble dry for 10 min after the wash and contained the fewest number of organisms.
S. aureus was not isolated from any of the fabrics after the washing process (Table II). The environmental organisms isolated were similar to those isolated previously and were found in similar numbers for the different fabrics.
Comparison of different domestic washing machines
The two uninoculated control squares of scrub suit did not show any evidence of S. aureus. However, environmental organisms other than S. aureus were detected. Using the broth detection method, the TVC of the material direct from the laundry was 80 cfu, compared with 680 cfu for the material transported and kept at room temperature for the same time as the other samples.
Discussion
40 8C wash cycle
Several physical and chemical factors are responsible for the removal of microbes by normal laundering processes.6 Organisms are diluted during washing, and soaps and detergents loosen soil and are bactericidal. Heat from the washing machine and from drying and ironing are effective in destroying micro-organisms, and chlorine and rapid changes in pH further reduce contamination. Recent studies have shown that a satisfactory reduction in microbial contamination can be achieved at low temperatures (22–50 8C) when the cycling of the water, wash formula and amount of chlorine are carefully monitored and controlled.7 National Health Service guidelines recommend that linen (defined as all articles for laundering)
S. aureus was not isolated from any square after the wash cycle (Table I). The squares that were removed immediately after the wash cycle before drying showed the greatest number of organisms retrieved, mainly oxidase-positive Gram-negative bacilli. Tumble drying or ironing reduced the TVC and when both were performed sequentially, bacteria were no longer detected.
60 8C wash cycle The 60 8C wash produced similar findings to the 40 8C wash but with a greater reduction in TVC (Table I).
Table I Total viable counts on scrub suit fabric after 40 8C and 60 8C wash cycles determined by both broth and contact methods Procedure
Total viable count (bacterial count of Staphylococcus aureus) from single fabric squares 40 8C wash cycle 60 8C wash cycle Broth (cfu/mL)
Fabric removed after wash cycle WashedCair dried WashedCair driedCironed WashedCtumble dried WashedCtumble driedCironed
O1!10
10
(0)
1.9!109 (0) 50 (0) 330 0 (0)
Contact (cfu)
Broth (cfu/mL)
O1!1010 (0)
210 (0) 4 (0)
4700 (0) 6 (0)
20 (0) 0 (0)
5
66
(0)
0 (0)
10
Contact (cfu)
(0)
O1!10
10
O1!10
0 (0)
Each row represents one fabric square washed at 40 8C and one at 60 8C. cfu, colony-forming units.
7 0 (0)
92 Table II
S.N. Patel et al. Comparison of different fabrics laundered at 40 8C and tumble dried for 30 min: total viable count
Type of material
Total viable count (bacterial count of Staphylococcus aureus) from a single square of each material Broth (cfu/mL) Contact (cfu)
100% polyester—rough texture 100% polyester—smooth texture 100% cotton velvet 100% cotton—T shirt material 55% cottonC45% polyester Wool—blend tweed
1250 (0) 250 (0) 1250 (0) 1250 (0) 750 (0) 1250 (0)
28 15 52 30 78 73
(0) (0) (0) (0) (0) (0)
Each row represents a single square of material. cfu, colony-forming units.
should be divided into three categories: used (soiled and foul), infected and heat-labile. 1 Infected linen is that from patients with or suspected of having a variety of communicable diseases. For used and infected linen, the washing process should have a disinfection cycle in which the temperature in the load is maintained at 65 8C for not less than 10 min or, preferably, at 71 8C for not less than 3 min. Additional time is recommended to allow mixing and heat penetration. Heat-labile linen is likely to be damaged by these temperatures and is processed in a cooler wash with the addition of certain chemicals, e.g. sodium hypochlorite. Recommendations for hospital laundering cannot be applied to the domestic situation. The majority of domestic laundering is at 40 8C or 60 8C followed by tumble drying or ironing, and does not use added chemicals. Unlike commercial machines, the wash load in domestic washing machines is not held at a particular temperature. As soon as the required temperature is achieved, the programme advances and there is no further heating of the water. The temperature gradually decreases as the wash programme continues. This study used a new domestic washing machine that had passed the manufacturer’s quality control with respect to the initial temperature achieved.
Ayliffe and Collins did not recommend home laundering because temperature control was not sufficient to ensure that uniforms were sterile.8 A small study of laundering of uniforms in domestic washing machines concluded that it was safe provided they were washed at not less than 50 8C and then ironed dry with a hot iron.9 The researchers used a contact method for retrieval of organisms from uniforms contaminated with Serratia marcescens. Identification of the organisms retrieved was not attempted. Our results suggest that the contact method was less sensitive than the broth method. All the organisms that were retrieved after the 40 8C and 60 8C wash cycle were derived from the washing machine and not the initial inoculum of S. aureus. Washing was sufficient to remove heavy contamination with S. aureus. However, the washing process itself resulted in contamination of the fabric with a mixture of environmental bacteria. Tumble drying and/or ironing were sufficient to remove these process-related bacteria. The findings were not affected by the type of fabric. Similar observations have been made in hospital-laundered linen.10 The results demonstrate that theatre scrubs or workers’ own clothing can be safely washed at 40 8C if tumble dried for 30 min and/or ironed. Potential pathogens other
Table III Comparison of different washing machines: total viable count from uninoculated squares laundered using 60 8C wash cycle Washing machine 1 2a 3 4
Total viable count from a single square for each machine of each material Broth (cfu/mL) Contact (cfu) 180 1 300 200
A single square of material was tested in each machine. cfu, colony-forming units. a Machine 2 was automatically set to tumble dry for 10 min after washing.
576 6 1584 360
Home laundering of uniforms than S. aureus should now be assessed by these methods.
References 1. Department of Health. Hospital laundry arrangements for used and infected linen. Health service guidelines HSG 95 (18). London: NHS Executive; 1995. 2. Perry C, Marshall R, Jones E. Bacterial contamination of uniforms. J Hosp Infect 2001;48:238—241. 3. Anonymous. Health Secretary announces MRSA target. CDR Wkly 2004;14:3.
93 4. Hedin G. Staphylococcus epidermidis–hospital epidemiology and the detection of methicillin resistance. Scand J Infect Dis Suppl 1993;90:1—59. 5. Miles AA, Misra SS, Irwin JO. The estimation of the bacterial power of the blood. J Hyg 1938;38:732—749. 6. Walter WG, Schillinger JE. Bacterial survival in laundered fabrics. Appl Microbiol 1975;29:368—373. 7. Blaser MJ, Smith PF, Cody HJ, et al. Killing of fabricassociated bacteria in hospital laundry by low-temperature washing. J Infect Dis 1984;149:48—57. 8. Ayliffe GA, Collins B. Laundering of nurses’ dresses at home. J Hosp Infect 1989;13:91. 9. Callagan I. Bacterial contamination of nurses’ uniforms. A study. Nurs Stand 1998;13:37—42. 10. Nicholes PS. Bacteria in laundered fabrics. Am J Public Health Nations Health 1970;60:2175—2180.