Evaluation of disinfecting procedures for aseptic transfer in hospital pharmacy

1 October 2011

J.C. Smith All Wales Quality Assurance Pharmacist,
St Mary’s Pharmaceutical Unit Cardiff & Vale
Cardiff & Vale University Health Board, Cardiff, UK

It is current practice in UK NHS hospital aseptic units to employ one of two methods to surface disinfect components required in Grade A pharmaceutical environments. These two methods are spraying and wiping with 70% IMS and gassing with hydrogen peroxide vapour. Both systems have their advantages and disadvantages. The IMS system is quick, relatively inexpensive, ideal for individual dispensing processes, but is difficult to validate. The gassing systems is a more time consuming process, is ideal for batch processing, effective against spores, relatively expensive and easier to validate. Gassing systems are expected to demonstrate a reproducible six log reduction in Bacillus stearothermophilis spores.

A method was developed to assess biocides in a variety of formats, when applied to contaminated hard surfaces. Biocides assessed included Klercide™ Biocide A (quaternary ammonium (QUAT) compound and a biguanide); B (stabilised chlorine dioxide and a QUAT); C (6% hydrogen peroxide), D (NN, Bis (3-amino propyl) dodecylamine); and 70% denatured ethanol (IMS). This method was modified from suspension methods and based on the British Standard 13697 and Association of Analytical Chemists standard.

The results of this work demonstrated that:

  • Biocides alone are not very effective against bacterial spores
    70% IMS spraying and wiping achieves a 1.5 log reduction in bacterial spores
  • Wiping is an essential part of the process
  • The ability to remove spores is effected by the spore surface structure and the weave of the wipe.
  • Pre-impregnated wipes are recommended as spraying biocide into dry wipes may leave areas with limited biocide
  • Using hydrogen peroxide spray or wipe within the transfer process would increase the ability to reduce the numbers of spores.

This study concluded that the use of 6% hydrogen peroxide spray or wipe in the transfer process would be advantageous with regards to reduction of bacterial spores. The potential for operator harm and product contamination would require further investigation and validation. There is potential to include hydrogen peroxide as the first spray and wipe process in a two spray and wipe technique. 70% IMS could then be used as the second spray and wipe system.

Acknowledgements: Co workers, Manita Mehmi, Lindsay Marshall, Peter Lambert, School of Life and Health Sciences, Aston University, Birmingham B4 7ET UK. This work has been financially supported through the provision of a Ph.D. studentship (Manita Mehmi) by the Engineering and Physical Sciences Research Council EPSRC and Shield Medicare Ltd (CASE/CHA/06/05).

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