N.47 – Glossary for Microbiological Air Environmental Monitoring


Microbiology according USP 38 – The United States Pharmacopeial – Document (1116) Aseptic Processing Environments – Page 1201, 1202.

-Airborne Particulate Count – The total number of particles of a given size per unit volume of air.

-Airborne Viable Particulate Count – The recovered number of CFU per unit volume of air.

-Air Changes – The frequency per unit of time that the air within a controlled environment is replaced. The air can be recirculated or totally replaced.

-Air Sampler – Device or equipment used to sample a measured amount of air in a specified time to quantitate the particulate or microbiological status of air in the controlled environment.

-Aseptic – Technically, the absence of microorganisms, but in aseptic processing this refers to methods and operations that minimize microbial contamination in environment where sterilized products and components are filled and / or assembled.

-Aseptic Processing – An operation in which a products assembled or filled into the primary package in an ISO5 or better environment and under conditions that minimize the risk of microbial contamination. The ultimate goal is to produce products that are as free as possible of microbial contamination.

-Barrier System – Physical barriers installed within an aseptic processing room to provide partial separation between aseptically gowned personnel and critical areas subject to considerable contamination risk. Personnel access in the critical zone is largely unrestricted. It is subject to a high level disinfection.

-Bioburden – Total number and identity of the predominant microorganisms detected in or on an article.

-Clean Room – A room in which the concentration of airborne particles is controlled to meet a specified particulate cleanliness Class. In addition, the concentration of microorganisms in the environment is monitored; each cleanliness  Class defined is also assigned a microbial level for air, and personnel gear.

-Commissioning of a Controlled Environment – Certification by engineering  and quality control that the environment has been built according to the specifications of the desired cleanliness Class and that, under conditions likely to be encountered under normal operating conditions (or worst case conditions), it is capable  of delivering an aseptic process. Commissioning includes media-fill runs and results of the environmental monitoring program.

-Contamination Recovery Rate –T he contamination recovery rate is the rate at which environmental samples are found to contain any level of contamination.  For example, an accident rate  of 1% would mean that only 1% of the samples taken have any contamination regardless of colony number.

-Controlled environment – Any area in an aseptic process system for which airborne particulate and microorganism levels are controlled to specific levels, appropriate to the activities conducted within that environment.

-Corrective action – Action to be performed that are according to standard operating procedures and that are triggered when certain conditions are exceeded.

-Critical Zone –Typically the entire area where products and the containers and closures are exposed in aseptic processing.

-Detection frequency –The frequency with which contamination is observed in an environment. Typically expressed as a percentage of samples in which contamination is observed per unit of time.

-Environmental isolates – Microorganisms that have been isolated from the environmental monitoring program.

-Environmental Monitoring Program – Documented program implemented via standard operating procedures that describes in details the methods and acceptance criteria for monitoring particulates and microorganisms in controlled environments (air, surface, personnel gear). The program includes sampling sites, frequency of sampling, and investigative and corrective actions.

-Equipment Layout – Graphical representation of an aseptic processing system that denotes  the relationship between and among equipment and personnel. This layout is used in the Risk Assessment Analysis to determine sampling site and frequency of sampling based on potential  for microbiological contamination of the product/container/closure Systems. Changes must be assessed by responsible managers, since unauthorized changes in the layout for equipment or personnel stations could result in increase in the potential for the contamination of the product/container/closure system.

-Isolator for Aseptic Processing – An aseptic isolator is an enclosure that is over-pressurized with HEPA filtered  air and is decontaminated using an automated system. When operated as a closed system, it uses only decontaminated interfaces or rapid transfer points for material transfer. After decontamination they can be operated in an open manner with the ingress and/or egress of material through defined openings that have been designed and validated to  preclude the  transfer of contamination. It can be used for aseptic processing activities or for asepsis  and containment simultaneously.

-Material Flow – The flow of material and personnel entering controlled environments should follow a specific and documented pathway that has been chosen to reduce or minimize the potential  for microbial contamination of the product/container/closure system. Deviation from the described flow could result in increase in the potential for microbial contamination. Material/personnel  flow can be changed, but the consequences of the change from a microbiological point of view should be assessed by responsible managers and must be authorized and documented.

-Media fill – Microbiological simulation of an aseptic process by the use of growth media processed in a manner  similar to the processing of the product and with the same container/closure system being used.

-Media Growth Promotion – Procedure that references Growth Promotion Test of Aerobes, Anaerobes and Fungi in Sterility Tests to demonstrate that media used in the microbiological environmental  monitoring program, or in media fill runs, are capable of supporting growth of indicator microorganism and of environmental isolates from samples obtained through the monitoring program on their corresponding ATTC strains.

-Product Contact Areas – Areas and surface in a controlled environment that are in direct contact with products, containers, or closures and the microbiological status of which can result in potential microbial contamination of the product/container/closure system.

-Restricted Access Barrier System (RABS) – An enclosure that relies on HEPA filtered air over-spill to maintain separation between aseptically gowned personnel and the operating environment. It is subject to a high level of disinfection prior to use in aseptic process. It uses decontaminated (where necessary) interfaces or RTPs for materials transfer. It allows for the ingress and or egress of materials trough defined openings that have between designed and validated to preclude the transfer of contamination. If opened subsequent decontamination, its performance capability is adversely impacted.

-Risk Assessment  Analysis –Analysis of the identification of contamination potential in controlled environments that establish priorities in terms of severity and frequency and that will develop methods and procedures that will eliminate, reduce, minimize, or mitigate their potential for microbial contamination of the product/container/closure system.

-Sampling Plan – A documented plan that describes the procedures and methods for sampling a controlled environment; identifies the sampling sites, the sampling frequency, and number of samples; and describes the method of analysis and how to interpret the results.

-Sampling Sites – Documented geographical location, within a controlled environment, where sampling for microbiological evaluation is taken. In general, sampling sites are selected because of their potential for product/container/closure contacts.


USP 38 – The United States Pharmacopeial – Document (1116) Aseptic Processing Environments -Page 1201, 1202