1408


Table 1. Simulated Cycle Parameters Programmed by the Detergent Supplier According to Industry Standards Stage 1 2 3 4 5 6 7 8 9


Process


Spectrum EU industrial washing system (total, 120 mL) Thermal disinfection Drain


Sodium hypochlorite 15% (50 mL) Drain Rinse Drain


10


Sour rinse peracetic acida (50 mL) Drain Spin


Total cycle time aPeracetic acid: acetic acid and hydrogen peroxide.


Water Volume, L 21.5 21.5


29.5 22 26


Joanna Tarrant et al


Temperature, °C 40 75


…… 60


…… Cold input …… Cold input ……


Time, Minutes 2


10 … 5 … 2 … 2 …


…… 2 ~90


Fig. 1. Comparison of methods for C. difficile spores recovered from NHS (100% cotton) sheet swatches with BSA soiling at low (0.3 g/L) and high (3 g/L) (mean ± SE, n=6).


tie, and put into the red ‘infected linen’ bags. The bags were transported to the laundry the same day. Individual sample swatches were placed in 50-mL Falcon tubes


with 30mL of MRD; viable spores were recovered using the vortexing method (5 seconds 5 times on high speed). Swatches were removed, and suspensions were heat shocked in a water bath at 80°C for 10 minutes. Suspensions were then vacuum filtered. Agar plates were incubated anaerobically at 37°C for 48 hours. The sampled sheets were then transported to the laundering


facilities immediately after sampling and washed in a washer extractor (30 kg commercial washer extractor) cycle meeting the minimum requirements of HTM 01-047 and were handled according to BS EN 14065:2002.12 Post-wash samples were pro- cessed with the same method used for pre-wash samples.


Industrial laundering


At the collaborating NHS-approved commercial healthcare laundry, the bags were transferred to the ‘dirty’ side of the facility, and the unopened alginate bags were loaded into a washer


Fig. 2. In vitro assessment of the recovered C. difficile spores after being processed in a washer extractor: the original inoculum (log10 cfu/ml) (■), per inoculated swatch (■) and per previously sterile swatch (□). Strain types NCTC 11209 and ribotype 001/ 072 (mean ± SE, n=4).


extractor for a wash cycle at 75°C for ≥3 minutes with 8 minutes mixing time using the same industrial detergent system used in the simulated washes. The sheets were then transported to the ironer bed, where they were pressed and dried at 175°C with 4 bars of pressure for 3 seconds (calendaring).


Identifying clinical strains


All presumptive C. difficile positive plates were confirmed by the gold-standard latex agglutination and long-wave ultraviolet fluorescence test. Ribotyping was then performed by polymerase chain reaction (PCR) with capillary gel electrophoresis (CE- ribotyping), at a Public Health England (PHE) laboratory (Newcastle, UK).


Statistical analysis


All statistical analyses were performed with SPSS version 22 software (IBM, Armonk, NY). The significance value for all tests was set at P≤.05. Depending on normality of the distribution of the data, either a 1-way analysis of variance (ANOVA) or inde- pendent t test was conducted. For nonparametric data, a Mann-


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