Monitoring aseptic units - a microbiology audit tool

1 3 0 • H O S P I TA L P H A R M AC I S T Aseptic preparation of medicines in hospital pharmacy units usually comprises the combination of licensed sterile ingredients in a manner that will ensure that the resulting product, in its final container, is sterile. One of the inherent weaknesses of this activity is that aseptically prepared medicinal products cannot be tested for sterility as would normally be the case for other sterile manufactured medicines. There are two reasons for this. First, such preparations are usually prepared as single items for individual patients. If the product were to be subjected to the pharmacopoeial test for sterility there would be no medicine left to administer to the patient. Second, and perhaps less obviously, a sample for sterility testing cannot be taken without compromising the integrity of the final container (eg, the syringe) thereby exposing the remainder of the medicine to possible microbial contamination. The pharmacist responsible for releasing the medicine therefore relies upon the overarching quality assurance systems in place to ensure that the medicine is sterile. Good quality assurance systems include appropriately trained staff working in accordance with validated procedures, using tested and calibrated equipment, and undertaking aseptic preparation in a clean environment that is routinely monitored. Standards have been set for the microbiological cleanliness of the immediate (and background) environment in which the manipulation of aseptically prepared medicines occurs. The maintenance of a suitably clean working environment is assessed via a programme of routine environmental monitoring of both physical and microbiological parameters. The minimum frequencies for such monitoring have been established for the NHS. In most hospital pharmacy aseptic units, microbiological environmental monitoring is undertaken by pharmacy staff.However, in my experience, there is a lack of pharmaceutical microbiology expertise most units so the identification of any contaminating microorganisms detected is often carried out by an outside agency. This may be the hospital’s own microbiology laboratory or a laboratory belonging to the Health Protection Agency (HPA). In some cases the laboratory might incubate the settle plates, contact plates, swabs and broth cultures for the pharmacy aseptic unit and may also prepare and provide the media used by the pharmacy staff to monitor the environment. The environment in which an aseptic product is prepared is critical to the quality of the finished product Pharmacy aseptic units should monitor