Good contamination control practices and adherence to established, written SOPs can minimize cross-contamination in isolators and bio-safety cabinets.

Isolators (Figures 1 and 2) and bio-safety cabinets, also known as “safety cabinets,” “biocontainment isolators,” “containment isolators,” or “barrier isolators” (Figure 3) are well accepted as cost-effective, convenient, and compact controlled environments that provide product and personnel protection. These devices consist of protective enclosures that physically isolate products from the background environment (the room outside the isolator), either because the product of interest is unsafe and therefore needs containment or the product cannot tolerate contamination and therefore needs isolation. Collectively, they are known as “separative enclosures,” or more properly, “separative devices.”

The term “isolator” is usually reserved for pharmaceutical and pharmacy applications, whereas the term “bio-safety cabinet” (BSC) is used in the pharmacy, biotechnology, and microbiology industries. For this discussion, we will consider that isolators and Class II bio-safety cabinets (and associated transfer devices) in biotechnology, microbiology, pharmaceutical and pharmacy applications are used as ISO Class 5 devices in terms of air particle cleanliness and are maintained as sterile environments to a sterility assurance level (SAL) ranging from 10-3to 10-6depending upon application.

Some applications, such as the handling of cyto-toxic drugs, potent hormones, and radiopharma-ceuticals, require both containment and isolation to achieve both protection of personnel from the product and protection of the product from contamination. Brian Midcalf, Chairman of the Pharmaceutical Isolator Working Party and User Group and Assistant PTQA Course Director, University of Leeds, UK, points out that progression from product isolation to product containment to product isolation and containment represents movement along what could be considered the “separation continuum.” These activities would typically be done in a Class II bio-safety cabinet or compounding aseptic containment isolator (CACI) where the necessary levels of air particle control and sterility would be maintained.

Figure 1. Pharmaceutical
Isolator (Photo courtesy of Getinge,
La Calhene)

Figure 2. Compounding Aseptic
Isolator (Figure courtesy of NuAire, Inc.)

Figure 3. Bio-safety Cabinet
(Photo courtesy of The Baker Company)