Disinfectants are biocidals, and biocidal activity is measured by the minimum bactericidal concentration (MBC). When a microorganism is first exposed to a disinfectant and subculturing is not possible, it is deemed to have been killed. The concentration at which the microorganism is killed is known as biocidal activity. The effects of antibiotics, such as penicillin and cephalosporin, are also described in terms of biocidal activity (1).
Several forums and publications have claimed that disinfectants must be rotated in biotechnology and pharmaceutical manufacturing settings to prevent the target organisms from developing resistance. Chapter <1072>, "Selection of a Disinfectant for Use in a Pharmaceutical Manufacturing Environment," in USP 30 addresses disinfectant rotation. It states that:The development of microbial resistance to antibiotics is a well-described phenomenon. The development of microbial resistance to disinfectants is less likely, as disinfectants are more powerful biocidal agents than antibiotics and are applied in high concentrations against low populations of microorganisms usually not growing actively, so the selective pressure for the development of resistance is less profound. However, the most frequently isolated microorganisms from an environmental monitoring program may be periodically subjected to use dilution testing with the agents used in the disinfection program to confirm their susceptibility.
The Japanese Pharmacopoeia, British Pharmacopoeia, and European Pharmacopoeia do not currently address the issue of disinfectant rotation.
Annex 1 of the European Commission's Good Manufacturing Practice (GMP) Guidelines, "Manufacture of Sterile Medicinal Products" states, "Where disinfectants are used, more than one type should be employed. Monitoring should be undertaken regularly in order to detect the development of resistant strains" (2).
But, the US Food and Drug Administration does not mention the rotation of disinfectants in its equivalent guideline Sterile Drug Products Produced by Aseptic Processing—Current Good Manufacturing Practice (3). This discrepancy raises the question of whether the technique of rotating disinfectants has a sound scientific rationale.
The biotechnology and pharmaceutical industries usually clean equipment with a detergent and use a disinfectant to reduce or eliminate microbial contamination. These industries usually call the process of reducing microbial contamination "disinfection," but the correct term is "sanitation" or "sanitization." As a side note, the probability of finding a true pathogen in an environment that complies with current good manufacturing practice (CGMP) is quite low.
This article uses the following definitions, which are described in references 5 and 6: