Mold contamination has been considered a hazard in residential and commercial buildings for many years. In the past few years, however, mold contamination issues in pharmaceutical products have caught the attention of regulators. In the wake of mold findings and patient deaths, regulators have honed in on compounding pharmacies that are alleged to be deficient in their contamination control practices (1).
Even though there is a lot of buzz about this topic, there is very little understanding with regard to the nature of mold, the reason it is found in cleanrooms, and how it happily proliferates in the cleanroom environment. All “mold” cannot be placed in the same basket as mold is capricious. To explain this point, let us consider the mold found in the now so famous New England Compounding Center (NECC) pharmacy. Exserohilum rostratum, Aspergillus fumigatus,and the common cleanroom mold Cladosporium were the isolates recovered from the sterile products aseptically compounded in an ill-managed pharmacy. All over the Internet, it was an interesting read when Exerohilum was referred as a black mold and Aspergillus as a common mold; as there are many other black and common molds, such generalization of molds can lead to misconceptions about their characteristics. This is what had occurred, as important characteristics of Exserohilum rostratum and Aspergillus fumigatus were not presented in the publications that describe the NECC incident.
Aspergillus fumigatus is a fungus whose spores are ubiquitous in the atmosphere; it is also an opportunistic human pathogen in immuno-compromised individuals, causing potentially lethal invasive infections. The species is known to reproduce by asexual means (A.fumigatus-asexual reproduction). However, this mold also possesses a fully functional sexual reproductive cycle that leads to the production of cleistothecia and ascospores, which is the teleomorphic/sexual stage called Neosartorya fumigata. It is this understanding of phase specific structures that allows for successful mold remediation. The asexual phase of a mold may be killed by many disinfectants while the sexual phase may not be killed even by sporicidal agents if the correct contact time and dilution are not used during disinfection. This is also the very reason behind disinfectant qualification studies.
Similarly Exserohilum rostratum is the asexual stage (anamorph) while Setosphaeria rostrata is the sexual stage (teleomorph) of the same mold. Microbiologists in the quality control (QC) laboratory are often not microbiologists by profession. Many biochemists or others have learned the art of microbial testing. Lack of understanding of mold, their origin, their prevalence, as well as modes of proliferation and mode of infection is what leads to mold-related contaminants in products, thereby creating undesired consequences.