Transfer Disinfection Transfer Disinfection ValidationValidation

Sarah Hiom

Cardiff and Vale NHS Trust

Aseptic PreparationAseptic Preparation

Isolator TechnologyIsolator Technology

High contamination riskHigh contamination risk

Disinfection (70% alcohol)Disinfection (70% alcohol)

Transfer into controlled work zoneTransfer into controlled work zone

Validation of Disinfection TransferValidation of Disinfection Transfer

• Current methods Current methods

Swabs/Contact platesSwabs/Contact plates

• Lack sensitivityLack sensitivity

Not appropriate for assessing disinfection Not appropriate for assessing disinfection

AimAim

1.1. To develop and validate an accurate in To develop and validate an accurate in house disinfection assessment methodhouse disinfection assessment method

2.2. To use this method to benchmark To use this method to benchmark contamination levels and compare contamination levels and compare disinfection transfer procedures in pilot disinfection transfer procedures in pilot sites across Walessites across Wales

MethodMethod

Validate new methodValidate new method

• Background countBackground count

• Effect of residual alcohol on recovery ratesEffect of residual alcohol on recovery rates

• Determining % recoveryDetermining % recovery

% Recovery% Recovery

S.epidermidisS.epidermidis stock culture = 55cfu/100μl stock culture = 55cfu/100μl

SSaammppllee ssiizzee CCffuu//aammpp ((ssdd)) %% RReeccoovveerryy

AAmmppoouullee ++ 1100μμll SS..eeppii nn==99 44..88 ((11..77)) 8877%%

Contact Plate Contact Plate ~ 40%~ 40%

SwabSwab ~ 20%~ 20%

Sampling ConceptSampling Concept

Benchmark Contamination LevelsBenchmark Contamination Levels

• 50ml glass vial50ml glass vial

• Batch (6) stored in unit for 5 daysBatch (6) stored in unit for 5 days

• Bioburden determined after each disinfection point Bioburden determined after each disinfection point

during transfer to critical work zone (n during transfer to critical work zone (n 5) 5)

Hospital 1

0

5

10

15

20

25

30

35

40

45

Stock Transfer 1 Transfer 2

CF

U p

er v

ial

w ipe

spray

p = 0.3p = 0.06

p = 0.01

Mann-Whitney TestConfidence Intervals at 95%

p = 0.03

Pilot conclusionsPilot conclusions

• Novel sensitive method to assess disinfection transfersNovel sensitive method to assess disinfection transfers

• Spray & wipe transfer methods significantly better at Spray & wipe transfer methods significantly better at

reducing bioburden than spray only procedures reducing bioburden than spray only procedures (P<0.1)(P<0.1)

• Better bioburden reduction when vial caps opened before Better bioburden reduction when vial caps opened before

alcohol spray disinfection transfers alcohol spray disinfection transfers (P<0.1)(P<0.1)

• Operational procedures showed transfer of up to 9 cfu/vial Operational procedures showed transfer of up to 9 cfu/vial

into critical work zonesinto critical work zones

Action limits?Action limits?

Bioburden (cfu/item)Bioburden (cfu/item)

Stock T 1 T 2

20 0 0 1 0 1 18 0 0 85 3 0 10 1 1 51 16 0 4 0 0

189 2 0 195 6 0 33 0 0 20 1 1 0 0 0 0 0 0 7 1 0

>100 3 1 >50 1 1

3 1 0 3 n/a 1 2 n/a 0

42 2.1 0.3

Action LimitsAction Limits

“…“…for transfer disinfection procedures to pass this for transfer disinfection procedures to pass this

validation test, results are expected to validation test, results are expected to

demonstrate demonstrate no greater than two colony no greater than two colony

forming unitsforming units from each item sampled within from each item sampled within

the critical work zone. the critical work zone. ””

SteriVal : Technical Information Sheet 3.3