Microbiology - Air sampling

[Yolanda74Moon]

Hello,

I look after the micobiological monitoring programme in our ISO 7 clean room.

We have had a upwards trend recently and I've been trying to get to the bottom of it, including putting in place extra controls, improving hygiene, cleaning etc...

Some of the samples are taken by QC, and recently, due to staff shortages in the quality dept, some have been taken by the production team.

I have noticed that the samples taken by production tend to be lower.
This could be because of several reasons:
- 1 less person in the room - less movement, less potential contamination.
- quality operator's handling techniques need to be improved, to avoid contamination.
- the production team are a bit more careful, knowing there is real time monitoring
- the corrective actions are starting to take their effect and the contamination is coming under control.

However, I've noticed the agar on the petri dishes looks less "pock marked" - the air samples are taken using a mechanical air aspiration system that sucks 1000L of air in and deposits it directly onto petri dishes. Normally, there are concentric circle "pock marks", but on the recent samples taken by production, I can't see the "pock marks" - I've uploaded a few photos.

There's also one petri-dish where it looks like the air sampler has been partially covered.

The air sampler is calibrated, and within the manufacturer's calibration window, the petri dishes are purchased sterile, with CoA detailing fertility tests, the supplier hasn't changed, the incubation time and conditions haven't changed either.

The air sampler is automatically programmed to sample 1000L, however, I don't have a downloadable proof of the history of the sample times / volumes, and I just have to trust that it's being done correctly.

Does anyone have any experience with this?

Kind regards

 

[Nichole F]

This might seem like a silly question, but are both sets of users removing the solid covers? I'm somewhat familiar with air samplers and I know some brands have a solid cover and a cover with holes that would generally produce the "pocks" you mentioned. Lack of those marks would indicate improper air flow. If the air sampler heads are not cleaned properly, they may become clogged and will limit air flow. Most air sampler companies also sell air flow rate check systems that you can use to ensure the proper airflow is maintained. Does your system not have data transfer capabilities? Most have USB cable or Bluetooth.

Are your agar plates being stored properly? If they are dried out, you will also not get the pock marks.

My best recommendation is to observe the process to see where the difference is occurring. I would guess this is due to user error but if you are able to eliminate that, contact the manufacturer of your air sampler. Their tech support should be able to help you identify the issue.