workshop on the biology of anthrax, cardiff – 12.03.14

An Agency of the Health and Safety Executive www.hsl.gov.ukAn Agency of the Health and Safety Executive

Workshop on the biology of anthrax, Cardiff – 12.03.14

Decontamination challenges: if you can kill Bacillus anthracis endospores you can probably kill most pathogens - but how best

to achieve it?

The Health & Safety Laboratory

Alan Beswick

An Agency of the Health and Safety Executive

Outline of today’s presentationOutline of today’s presentation

Who we are

What we did and why we did it

Main findings

Implications

A workable SOP to take forward


HSL: who are we, where are we?HSL: who are we, where are we?

320+ staff

90+ PhDs

80+ MScs

550 acre site in

the Derbyshire

Peak District, UK

Widest science base of any equivalent European Laboratory – www.hsl.gov.uk

A big site for (some) big experimentsBut we do small stuff too….!


The context - use of whole room fumigationThe context - use of whole room fumigation

Decontamination can include use of whole room fumigation This must be able to combat potentially malicious microbiological

release for bio-security applications

Some examples of whole room fumigants:

H2O2 – Hydrogen peroxide – as vapour & dry mist (multiple systems)

ClO2 – Chlorine dioxide - a true gas

CH2O - Formaldehyde vapour


What we need from a fumigation systemWhat we need from a fumigation system

Routine decontamination, e.g. for maintenance

Consistent, reproducible and effective killEasily removed from the treated/contained areaLeave room/laboratory and it’s equipment undamaged (ideally)

Emergency decontamination (e.g. lab spill or other release)

All of the aboveQuick and easy to deploy (ideally without requiring entry intothe room if CL3-based)Reliable (especially if equipment is to be resident in room orleft for long periods unused)


How do available systems match up How do available systems match up against each other?against each other?

Observed log reduction by fumigation system and organism

0

2

4

6

8 L o g R e d u c t i o n

Geobacillus C. difficile M. fortuitum Vaccinia Organism

H2O2a CL02 Formaldehyde

H2O2b H2O2c Ozone Error bars represent interquartile range Dashed line represents four-log reduction

See Beswick et al. (2011). Applied Biosafety. Volume 16 (3); 139-157.


Aims of biosecurity-related workAims of biosecurity-related work

Biocidal efficacy of formaldehyde vapour against a range of challenge microorganisms and room scenarios

Using HSL’s Controlled Atmosphere Chamber to evaluate methods for formaldehyde fumigant delivery and removal

From the steps above - develop a Standard Operating Procedure (SOP) that could be used by third party decontamination contractors.

Home Office wished us to consider the following:


The test chamber – furnished room The test chamber – furnished room examplesexamples

Domestic set up.

Office set up Externally monitoring fumigant levels

Laboratory set up


Fumigation delivery and removalFumigation delivery and removal

Wok fumigation + ammonia from Formaflow VAP2 Device

The Walker’s Whole Room Fumigation System with ammonia delivery & carbon bed

Wok fumigation + Airflow - mechanical ventilation

Direction of airflow


Microbiological challengesMicrobiological challenges

Some of the surrogate pathogens used to provided relevant challenges for the testing:

Bacillus atrophaeus – a spore forming surrogate for B. anthracis

Pantoea agglomerans – bacterial surrogate for Yersinia pestis

Coxiella burnetii – bacterial agent of Q Fever; 9 mile strain used (non-infectious; supplied by B Heinzen, US Rocky Mountain labs)

Vaccinia virus – as a surrogate for Variola (smallpox) virus

Geobacillus stearothermophilus – a standard reference strain & resilient bacterial spore former


Surfaces and location are importantSurfaces and location are important

Microbial challenges mainly presented dried down on 2cm x 2cm square coupons – Ikea furniture a popular material choice!!

Room Setting Material Location Laboratory Stainless steel Top of cupboard

Stainless steel Inside centrifuge, with lid almost closed

Formica On top of cupboard Formica Inside cupboard, near

back, doors - nearly closed Safety vinyl On floor

Office Billy Top of bookcase Billy Inside drawer, slightly ajar Vika On desktop Vika On shelf on bookcase Safety vinyl On floor, under desk

Domestic Billy Top of bookcase Billy Inside drawer, slightly ajar Vika On table Glass Inside mattress Safety vinyl On floor


Good H&S - fumigant levels should be Good H&S - fumigant levels should be known ......whether at peak or residualknown ......whether at peak or residual

Minirae 2000PID monitor: potential for routine hand held or static monitoring

PortaSens II monitor: potential for routine hand held or static monitoring

Bruel and Kjaer (type 1302) multigas monitor – used for

accurate comparative monitoring The Gasmet IR monitor

Several systems were evaluated for formaldehyde fumigant monitoring


Performance of sensorsPerformance of sensors

Minirae 2000PID monitor: potential for routine hand held or static monitoring

PortaSens II monitor: potential for routine hand held or static monitoring

Bruel and Kjaer (type 1302) multigas monitor – used for

accurate comparative monitoring The Gasmet IR monitor

Only two instruments able to cope with fumigant and humidity levels:

X

X


Findings - fumigant removal similar Findings - fumigant removal similar regardless of method used regardless of method used

• Mechanical air flow alone rapidly reduced formaldehyde fumigant to low levels (0-5ppm) – so often above WEL (2ppm) on completion

• Ammonia easy to deliver and effective for rapid neutralisation of fumigant – but can form 2o by-products that mimic formaldehyde

• Addition of a large carbon filter bed – in addition to ammonia – gave no obvious additional benefits to ammonia alone

• Off gassing often observed from soft materials in room - usually <10ppm and localised but often persistent (up to 96 hrs post treatment)


Were microorganisms killed by Were microorganisms killed by formaldehyde?formaldehyde?

Microbiological reductions >6-Log were possible with formaldehyde for most test challenges

Some variation in efficacy noted - dependent on microbiological type and location – 4 to 5 log reduction not unusual

Samples located within the drawer unit exhibited some of the lowest kill – indicative of limited penetration


Implications of findingsImplications of findings

Choice of monitoring equipment for measuring levels of fumigant is critical for efficacy and safety during treatment delivery

Only certain fumigant monitors are ‘up to the job’

Formaldehyde is an effective fumigant but there is potential for variation in efficacy depending on location/room layout etc. – validation can help

Methods for removing formaldehyde must be in place before fumigation. Aeration is as effective as any method, if it is physically possible

Furnishings should be checked for off gassing effects – some exposed materials may require disposal or extended periods of aeration

Knowledge gained allowed preparation of Draft SOP document


The next step – using the developed The next step – using the developed SOP in a ‘real’ buildingSOP in a ‘real’ building

Involvement in a GDS-led WASA exercise taught HSL much about SOP preparation and presentation

GDS asked HSL to road test the Draft SOP in a real building situation before inflicting it on a 3rd party Framework Supplier


A practical output from experimental A practical output from experimental evaluationevaluation

Optimisation of v1 of SOP allowed preparation of an improved v2 document for use by contract decontamination teams

We realised - having the right information is important but front end document has to be simple and easy to follow – e.g. flow charts


The practicalities of effective The practicalities of effective fumigant deliveryfumigant delivery

The optimised SOP was evaluated as part of a recent project funded by GDS – independent contractors used

This has included ‘real’ building tests (150m3 volume)

Considered – Risk assessment; PPE; sealing of doors & windows; levels of fumigant required; explosive risk; aeration of room; working above ground level


Building layout during contractor fumigation tests:

The four locations of the 1.5cm steel coupons seeded with Bacillus spores are indicated by small red circles;

- floor

- high shelf

- window ledge

- worktop

7-log reduction of B. atrophaeus achieved in all room locations

Independent users happy with SOP

Result….!!

The outcome of independent The outcome of independent testingtesting


The Health & Safety Laboratory

Acknowledgements

Thanks to:

S Casey & J Caddick (GDS)J Gawn (HSE)C Makison Booth (HSL)J Farrant (HSL)G Frost (HSL)J Holroyd (HSL)

workshop on the biology of anthrax, cardiff – 12.03.14

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