Pharmaceutical, biotech, and medical device cleanrooms today are faced with the increasing prevalence of molds that can lead to environmental monitoring excursions. Over the years, we have noticed mold issues associated with cleanrooms, cold rooms, door kick plates, incubators, and cleanroom startups. Molds, such as Aspergillus, have come from many sources in the cleanroom, such as bags, boxes, markers, intervention equipment, and cart wheels. These occurrences seem to be more prevalent. Aspergillus, Penicillium, Trychophyton, and other molds have, in some cases, caused significant microbial excursion issues that have resulted in adverse impacts on production.

This article will provide an overview of the different types of fungi, killing mechanisms of several of the germicides commonly available, selection criteria for disinfectants, test methods, and recommendations for reducing the likelihood of environmental excursions due to molds.

FIELD OBSERVATIONS
In the past year, we have consulted for several companies where Aspergillus,Penicillium, or Trychophy-ton outbreaks have resulted in environmental monitoring data excursions exceeding alert and action limits. One company used a high impingement application device for applying germicides, which exposed the sheet rock and surfaces behind the wall, leading to endemic mold issues.Another company experienced cleanroom startup delays after a construction shutdown due to the presence of Strepto-myces spores even after triple-cleaning of the facility. The facility required additional cleaning and monitoring eventsto establish a control state for routine operation.

Two other pharmaceutical companies set limits for zero mold and zero yeast; both of these companies developed outbreaks that made their limits impossible to maintain. Both had to go back and establish limits for molds and yeast in their operations. Molds, such as Aspergillus niger, have also been problematic in cold rooms where pharmaceutical and biotech companies store raw materials for theirclean-room operations.

One company reported an instance in which Aspergillus was actually growing in the tip of a marker brought into the cleanroom.¹ In another case, a company reported an incident where Trychophyton was brought into a cleanroom by means of a severe case of athlete’s foot infection. Since contamination can occur from the most unexpected sources and on any surface in a cleanroom, it is important to have a thorough solution for addressingmold issues and to have germicidal products that actually kill mold spores.

FUNGAL CHARACTERISTICS
Fungi are a large and diverse group of eukaryotic microorganisms. There are approximately 100,000 species of fungi, about 200 of which are pathogens. The two groups of fungi that have practical importance in the cleanroom aremolds and yeasts.

Generally, fungi can be differentiated easily into these two types based on the macroscopic appearance of their colonies. Those that produce opaque, creamy, or pasty colonies are called yeasts and those that produce cottony, woolly, fluffy, or powdery aerial growths above the culture medium are called molds. However, this division between yeasts and molds based on growth morphology is not clear-cut, since some yeasts can produce hyphae under specific conditions (e.g., Candida albicans), while many filamentous fungi possess a yeast-like phase at some point in their life cycle. Generally, yeast cells tend to grow as single cells that reproduce asexually in a process known as budding. Molds grow as masses of overlapping and interlinking hyphal filaments and reproduceby producing masses of spores in a variety of structures.