1 – WHICH IS THE TERMINOLOGY (GLOSSARY) INVOLVED IN MAM?
Active sampling, Air flow l/m, ALCOA, Bacteria, Colony forming unit (Cfu), Contact plate, Contamination, Culture Media, Culture plate, Data integrity, Disinfection, Fungi, Incubation, PQ, IQ, OQ Document, ISO, Yeast, Micron, Micro-organism, Moulds, Passive sampling, Petri dish, SDA agar media, Settle, Sterilization, TSA agar media, USP, Unviable particles, Viable particles.
2 – WHY IS THE MICROBIAL CONTENT OF THE AIR TESTED?
The air contains micro-organisms that are “positioned” on the airborne dust. Such micro-organisms can contaminate sterile pharmaceutical products, reduce the shelf-file of food, dairy products, infect patients in hospital, contaminate by moulds HVAC of building, destroy old artistic pictures, contaminate theatres, offices, schools, trains, etc.
3 – WHAT’S THE DIFFERENCE BETWEEN A PARTICLE COUNTER AND A MICROBIAL AIR SAMPLER?
The particle counter takes a quickly measuring of unviable particles; the microbial air sampler takes a measuring of viable particles. Particle counter cannot distinguish viable and unviable particles and doesn’t provide information on the microbiological content of the environment. The particle counter is the answer for an immediate unviable particle result, the microbial air sampler is the answer for a microbial content after incubation. Both methods are therefore used for E.M.
4 – WHAT IS THE DEFINITION OF MAM (MICROBIOLOGICAL AIR MONITORING)?
Microbial Air Monitoring (also called Viable Air Monitoring) has the purpose to capture samples of micro-organisms (bacteria, moulds, yeast) suspended in the air on a nutrient media (inside a Petri dish) with subsequent incubation to highlight their growth after 2-3 days for bacteria and 3-6 day for moulds and yeasts.
5 – WHAT TYPE OF NUTRIENT AGAR IS USED FOR MAM?
Tryptic Soy Agar (TSA) is typically used for total bacterial count of bacteria; Sabouraud Dextrose Agar (SDA) is used for mould or yeast growth.
The minimum amount of agar in each Petri dish should be 12-15 ml for Contact plate and 25 -30 – 35 ml for standard Petri dish.
6 – WHAT IS THE INCUBATION TIME AND TEMPERATURE?
Bacterial samples are typically incubated for 48-72 hours at 30-37°C. Moulds and yeasts are typically incubated for 4-6 days at 26-30°C.
7 – WHAT IS THE DIFFERENCE BETWEEN ACTIVE MICROBIAL AIR SAMPLING AND PASSIVE (SETTLE) METHODS?
Active microbial air sampler aspirates a known volume of air that impacts at constant speed on the agar media surface collecting viable particles of different size in microns.
With Passive method (settle) the viable particles fall naturally onto the surface of an open Petri dish and their collection vary based on air flow, humidity, temperature and size of micro-organisms.
The active method reports quantitative results in the format of cfu / 1000 litres of air (=1 cubic meter); the settle method reports the results that fall on open agar surface in 4 hours.
The number of cfu collected by the active method is much larger that with settle method and the quantitative results can be applied to action and alert levels.
8 – WHICH IS THE FREQUENCY OF MICROBIAL AIR SAMPLING?
The frequency varies by industry and application.
The pharma companies that produce sterile products have to follow the indication of the Health Authorities and the CCS (Contamination Control System) specific for each producer.
Indications can be found in the GMP Annex 1.
The frequency is daily for high-risk area and be-weekly or weekly for other sites.
The food, dairy, agro, poultry, beverage companies should make a preliminary investigation in their premises and production sites to find the best interval (daily, weekly, monthly?).
Dedicated Application Notes are available on request.
The frequency in hospital varies from high-risk sites (e.g.: type of operating room), high risk patient wards, etc, some indications are reported in the USP 1116 document Microbiological evaluation of Cleanrooms and other controlled environments.
Compounding pharmacies are requested a calibration every 6 months.
In the case of building, the HVAC should be monitored inside and outside to compare the results as number of cfu. The inside number should never be higher that outside.
9 – HOW OFTEN AN ACTIVE MICROBIAL AIR SAMPLER SHOULD BE CALIBRATED?
The time is bounded to the frequency of use, but generally is every 6-12 months.
Yes. If the calibration is out of limit during the final check, all the results of the previous period are not accepted. A check at regular interval is therefore requested using the specific instrument.
11 – WHICH IS THE CORRECT VOLUME OF AIR TO BE ASPIRATED BY AN ACTIVE AIR SAMPLER?
The volume depends from the expected number of micro-organisms present in the environment under control. The number of cfu /plate should easy to count (not more than about 150 cfu) and therefore it is necessary to establish the volume to be aspirated (e.g.: 300 – 500 – 1000 litres). The obtained result should be then related to 1000 litres of air (1 cubic metre of air).
12 – SHOULD THE CFU OBTAINED FINAL RESULT OF AN ACTIVE AIR SAMPLER MODIFIED BY A STATISTICAL TABLE?
The instruction manual of each sampler reports a statistical table that should be applied to overcame the problem that more than a micro-organism is captured on the same hole of the agar surface.
13 – WHY ARE STERILE ASPIRATING HEAD FOR DAILY USE AVAILABLE?
The aspirating head of the air sampler is typically stainless steel made and must be autoclaved each day with related documentation.
The availability of sterile techno-polymer heads (Daily Shift) that are used for a complete daily working shift avoids all the sterilisation iter and eliminated the possible false results.
14 – WHICH ACTIVE AIR SAMPLER SHOULD BE USED IN ISOLATOR AND RABS?
The command unit should be outside from the isolator to save inside space and reduce the risk of microbial contamination.
The only part inside is the aspirating head or the funnel model.
15 – HOW ARE COMPRESSED AIR / GAS MONITORED FOR POSSIBLE CONTAMINATION IN GRADE A AND B?
The active air sampler connected to the TRIO.GAS instrument is used according to the guidelines outlined on the ISO 8573-7 document.
16 – IS A RE-VALIDATION NECESSARY FOR A NEW ACTIVE AIR SAMPLER-INSTRUMENT INTRODUCTION?
Yes. A New validation is necessary. A specific protocol is available.
The sampling time of operator is reduced of 50% and a double number of tests are performed in comparison with 100 litres per minute.
There are several advantages:
- The use of different media at the same time (e.g.: TSA for bacteria and SDA for moulds)
- The use of the same media for real statistical results
- The use of the same media (e.g.: TSA) at different incubation temperature for bacteria and moulds
- To save operator time
- The application of continuous monitoring during the daily working shift
- To reduce the operator contamination risk because the plate handling is reduced
19 – IS IT POSSIBLE TO USE AN ACTIVE MICROBIAL AIR SAMPLER IN EXPLOSION RISK AREAS?
Yes. The model must be ATEX official certified.
The reason is connected to the fact that some companies prefer to have just a single type of culture plate to reduce the validation of each separated lot.
21 – HOW ARE VIRUS COLLECTED FROM AIR?
The aerosol virus are collected in liquid for rapid analytical identification using the AIR.BIO ONE VIRUS AIR SAMPLER.
