Microbial air contamination monitoring is a key process in facilities with special air cleanliness needs such as pharmaceutical, food, or cosmetic industries. 14698-1 normative establishes that environmental air sampling should be carried out considering the situation and using a device according to the written process and the instructions given by the manufacturer of the device respectively. With the IUL’s Spin air impaction air sampler an accurate volume of air is sampled by forcing it towards a surface, such as a Petri plate’s agar. After incubation, the colony count enables the assessment of the microbiological air quality. Air sampler grant users a compact, portable, simple solution to air sampling. Accuracy and precision-enhancing Spin technology enable Spin Air samples to outperform the accuracy of other air sampling systems.


Environmental air sampling assessment

The US Pharmacopeia (USP) chapter <797> establishes standardized protocols to ensure the preparation of sterile and compounded sterile preparations. A cornerstone of chapter <797> is the verification that the pharmacy’s cleanroom environment is maintained free from significant sources of contamination. One of the approaches used for this process is air sampling to detect bacterial and fungal organisms in the cleanroom environment. 14698-1 normative, which runs all the air sampling rules for cleanrooms and associated controlled environments, summarizes that the election of a device for air sampling should consider different factors such as the type and size of particles that can be sampled, the sensitivity of the particles, the characteristics of the device and the culture medium in which the microbiological particles are collected. However, which culture medium and bacteria must take into account when air sampling is carried out?

Culture medium

Overall, the 14698-1 normative establishes that the culture medium and the incubation conditions (such as temperature, duration, oxygen tension, and relative humidity) have to be selected according to the type of microorganisms expected in the clean environment. This selection also depends on the sample environment, process, and equipment that have been selected. Bacillus spp. are the most frequently isolated bacterial contaminants. However, Gram-negative rods, such as Enterobacteriaceae, Pseudomonas, Stenotrophomonas, Acinetobacter, and even Mycobacterium and Nocardia spp., are also recovered. Aspergillus, Acremonium, and Fusarium fungi are the most frequently isolated molds. However, the 14698-1 normative states that the culture medium must be non-selective and to include appropriate additives to compensate or reduce the effects when an antimicrobial activity is expected in the sampling.


environmental air sampling


How many plates and replicates i have to carry out?

The USP chapter <797> recommends using two types of agars: tryptic soy agar with polysorbate and lecithin (TSApl) for bacteria and malt extract agar (MEA) for fungi isolation. In contrast, the Controlled Environment Testing Association (CETA), the professional organization for individuals who certifies quality control personnel and cleanrooms, states in its 2021 certification application guide that a single plate method is acceptable, implying that it is not always necessary to use an additional medium specifically for fungi. Due to the discrepancies given by both guides, Weissfeld et al. studied the “Optimal Media for Use in Air sampling to Detect Cultivable Bacteria and Fungi in the Pharmacy”. Comparing TSApl versus MEA, the authors concluded that MEA yields 2.5 times more fungal isolates than TSApl, so the analysis of 5.5 years of data of 2.073 environmental air samples showed that two media (one bacterial and one fungal) must be used to effectively track and correct any problems. 

Sampling frequency

Sampling frequency has to be established in the sampling plan of each company but cannot be limited or little volumes to get representative results using the Formal System chosen and must be confirmed or modified, if necessary, in the following cases:

When the levels of alert and action are exceeded.

  1. After a prolonged break of activity.
  2. In the detection of infective agents in risk areas.
  3. Before significant maintenance in the ventilation system is made.
  4. After changes in the process that affect the environment of the cleanroom.
  5. When unusual results are registered.
  6. After changes in the cleaning or disinfection procedure.
  7. After unforeseen incidents which can contribute to biocontamination.

Spin Air to control microbial air contamination

Spin Air samplers grant users a compact, portable, simple solution to air sampling. Accuracy and precision-enhancing Spin technology enables Spin Air samplers to outperform the accuracy of other air sampling systems.