Environmental monitoring in a hospital aseptic preparation unit

Reliability, ease-of-use and sampling speed are key considerations when selecting an active air sampler for an environmental monitoring programme, but these needs may change over time, warns Cherwell Laboratories

Portsmouth PMU has been using Cherwell’s SAS air samplers and Redipor microbiological media since the 1990s

The Pharmaceutical Manufacturing Unit (PMU) of the UK’s Portsmouth Hospital Trust specialises in the aseptic preparation of pharmaceuticals and parenteral nutrition, cytotoxics and patient-controlled analgesia in a variety of administration devices. With two aseptic rooms, eight isolators, two preparation rooms and a checking and labelling area, an extensive environmental monitoring (EM) programme is in place that incorporates both active and passive air sampling to ensure the environment is free from microbial contamination.

The EM programme involves active and passive air monitoring as well as contact plates and is performed weekly (at a minimum) in all areas. Routine monitoring is performed with Tryptone Soy Agar (TSA) and also monthly with Sabouraud Dextrose Agar (SDA).

Monitoring can involve in excess of 50 active air samples, and the need to sample 1,000 litres of air at each location means high speed air samplers are essential to ensure monitoring is performed in a timely fashion and events can be reacted to if the need arises.

Validation is often required in an unmanned state and therefore work must be performed out of hours

Cherwell Laboratories, of Bicester in the UK, provides Portsmouth PMU with portable, high speed air samplers for general EM, Redipor prepared media for passive air sampling and specialist units for isolator monitoring. Validation is often required in an unmanned state and therefore work must be performed out of hours; having SAS Super 180 air samplers facilitates this. Isolator air samplers also enable the PMU to monitor sessions at its convenience without the risks involved in placing additional equipment into the isolator.

Formerly Queen Alexandra Hospital, Portsmouth PMU has been using Cherwell’s SAS air samplers and Redipor prepared microbiological media since the 1990s. When the PMU first started looking for an air sampler for EM, the original SAS System offered the best solution on the market. With sampling speeds of 180 litres/min, the SAS was the fastest sampler available and used a standard, readily available contact plate as the consumable. Furthermore, its portability enabled the user to conduct EM in several locations.

However, the units were heavy and Cherwell phased them out following the development of the SAS Super range. The new, easier-to-use and more portable SAS Super 180 continued to offer the high sampling speeds required by Portsmouth, and a unit was initially purchased in 2003, to use alongside the original SAS system. With its 180 litres/min sampling rate, the unit requires less than six minutes to complete a 1m3 sampling, reducing staff time and minimising disruption.

Active sampling method

The SAS air samplers use the proven active sampling method of direct, multi point impaction: airborne particles are drawn through the sampling head and impacted onto the agar media surface of a contact plate. Multi-point impaction ensures statistically sound results as they sample at a fixed rate.

Cherwell’s engineering department in its Bicester facility offers a calibration service with a fast turnaround time and can be arranged to minimise downtime and inconvenience.

Each stainless steel sampling head is located permanently inside the cabinet and connected to an external control unit that can control multiple sampling heads

In 2008, Portsmouth PMU relocated from its hospital site to a new, purpose-built manufacturing facility. This facility incorporated an increased use of isolator technology and presented a new challenge for monitoring. Therefore it now uses two specialist SAS units with eight sampling heads for EM within its isolators. Each stainless steel sampling head is located permanently inside the cabinet and connected to an external control unit that can control multiple sampling heads. The external control unit ensures that dedicated monitoring programmes can be readily established and controlled.

Portsmouth PMU was an early adopter of the new technology and the process of integrating it into new cabinets. An unexpected problem encountered during installation, due to the wiring system of the isolator cabinet, was dealt with quickly and efficiently by Cherwell’s in-house engineering department.

Cherwell has also been supplying Portsmouth with a reliable and flexible solution for its prepared microbiological media requirements, with a regular delivery of Redipor Prepared media since 2006; a standing order ensures it receives scheduled deliveries. Currently TSA and SDA irradiated contacts and 90mm settle plates are used for routine sessional and environmental monitoring with 90mm R2A used for routine water testing. A selection of single and double strength TSB is also used for routine operator and process validations.

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