Environmental monitoring determines the microbial and particulate content of clean room air and surfaces where manufacturing of sterile and non-sterile pharmaceutical products are undergoing so as to achieve and maintain aseptic conditions. There should be very few viable organisms present in the clean room air. However, operators within the clean room disperse large numbers of skin particles.
Many of these particles are contaminated with bacteria. The dispersal of contaminated particles by the clean room operator is greatly decreased by the wearing of occlusive clothing together with appropriate air ventilation.
Sampling for microbial contamination is necessary when people are present in the clean room during production. The purpose is to reduce air borne contamination where air is not critical in causing contamination. Environmental monitoring is classified into two types: viable monitoring, and non-viable particulate count monitoring.
(i) Viable Monitoring:
The viable monitoring is carried out by following methods:
(a) Active air sampling:
In this procedure, impact and agar impingement air samplers (Fig.19.4A) are used to sample a defined volume of air, embedding viable particulates onto sterile media strips and incubated to promote the growth of viable particulates. The microorganisms are counted and results are reported as the number of CFU per volume of air sampled.
(b) Passive air sampling (Settle plates):
In this case, there is little air movement (i.e. dead spaces) or where air flows converged or it is excessively turbulent. Such conditions are most likely to occur adjacent to doors, between HEPA’s in clean rooms, in corners of rooms, areas within the clean room where personnel to carry out specific operations.
The air microflora can be procured on plates containing growth media (Soya bean casein digest agar) when exposed for 2-4 hours (Fig.19.4B). The air borne microorganisms, typically attached to larger particles, will deposit onto open culture plates.
Microorganisms are usually found in the air of occupied rooms. Due to gravity, the average size of particles containing microbes will deposit and settle. By action of gravity, onto surfaces at a rate of approximately 1 cm/second. The plates are then incubated.
(c) Personal Monitoring:
The personnel wearing apron (coat) are meant for monitoring. The finger impressions are taken and pressed onto the surface of Replicates Organism Detection and Counting plates (RODAC).
The Petri dishes have flat agar surface above the edges of the dish, hence one can press it on flat surfaces from forehand, chest, left hand and right hand, before entry and exit from production area. Such Petri plates are incubated at different temperature for 24-48 h. Microbial growth recorded as cfu/cm2 (Fig.19.4C).
(d) Surface Tests:
The materials deposited onto the sampled surfaces are removed by sterile moistened swabs. Surfaces are sampled using direct contact plates method. The swabs are streaked onto the surface of solid growth media and are incubated properly. The swabs are dissolved in sterile diluent and viable count is determined (Fig.19.4D).
(ii) Non-Viable Particle Count Monitoring:
Particle counter used to sample a defined volume of air can measure a variety of particle of varying sizes from 0.5 to 5.0 µ. A particle counter is given in Fig. 19.5. Particle counts are recorded as the number of particles per volume of air sampled.
Results can be measured in per cubic foot or per cubic meter as per ISO 1464. It is useful in detecting significant deviations in gas or liquid cleanliness. It is applied for quantification and monitoring before, during and after operations.