GOSH selects Cherwell for support in excluding bacterial spores


Cherwell Laboratories, specialists in products for environmental monitoring and process validation, supported the Great Ormond Street Hospital Pharmacy Unit in developing a new triple-wrapped prepared media product to ensure the exclusion of bacterial spores during aseptic compounding validation

Aseptic compounding at the GOSH Pharmacy Unit

Validation of compounding in the hospital pharmacy is essential for demonstrating appropriate controls are in place to ensure asepsis of the process and the sterility of filled products (eg parenteral nutrition) and ultimately, to ensure patient safety.

In order to monitor the aseptic liquid transfer technique of compounder operators, Great Ormond Street Hospital (GOSH) routinely undertakes aseptic process simulation validation (media fill simulations) using tryptic soy broth (TSB).

Following a series of media fill simulation failures by multiple operators, due to the contamination of filled TSB units with Bacillus species, an investigation to identify the cause was conducted by GOSH.

This investigation found the contamination was not attributable to operator competency, as NHS aseptic transfer process guidance had been strictly adhered to.1

The contamination source was ultimately identified to originate from the TSB medium bottle surfaces following storage in an uncontrolled environment. No bacteria were recovered from the surface of large volume licensed medicinal products, confirming risk of spore contamination was during media fill validation and not actual medicine compounding.

GOSH sought an alternative microbiological media supplier to develop a way of ensuring the TSB units for aseptic process simulation validation were sterile, and Cherwell Laboratories were invited to collaborate with GOSH on this project.

To remedy the situation, Cherwell developed a sterile, triple packaged TSB product in line with Royal Pharmaceutical Society recommendations.2

GOSH Pharmacists found this prototype was easy to use and removed the risk of spore contamination of the medium prior to compounder validation, thereby eliminating false results and ultimately increasing workflow efficiency in the Pharmacy Unit by reducing false compounder system failures, as well as disinfection steps and use of toxic sporicidal sprays.



  1. NHS Pharmaceutical Micro Protocols Group, “Guidance for Aseptic Transfer Processes in the NHS: Addressing Sporicidal Issues,” (2015).
  2. Royal Pharmaceutical Society and the NHS Pharmaceutical Quality Assurance Committee, "Quality assurance of aseptic preparation services (QAAPS)," (2015).
Sign up for your free email newsletter

Featured Companies