3M Petrifilm Plate Identification
Hi All!
I am reaching out in regards to species identification when using 3M's Petrifilm plates. My plant currently does ATP, E. Coli/Coliforms, and Staph swabs. This isn't a food safety concern, but more so an interest in what we are dealing with when we get a positive swab. I've tried to do some research to no avail, so I was hoping the community might have some resources or advice.
Thank you all in advance!
Yours,
Shrimper
positive on which? they can all be a food safety concern, depends what the CC is, what you swabbed, what your process is and what your product is
positive on which? they can all be a food safety concern, depends what the CC is, what you swabbed, what your process is and what your product is
Hi Scampi,
I understand what you are saying. We have critical limits and such for everything related to our swabbing. When swabbing is conducted and after the swab has been collected, the area where the swab was taken is sprayed down with our sanitizer. This is in case of a positive result. For reference, I am in frozen seafood packing and processing. What I am more so interested in is if there is any way to identify the species of bacteria. This is more so a personal interest, that is why I am asking. Thanks for the help!
The 3M APC/ECC petrifilm instructions do indicate that isolated colonies can be removed for further identification. This is done by gently lifting the film and sampling a colony with a sterile loop, then streaking it onto a growth media. From there you could grow a culture and do gram staining or other identification tests. I've never personally isolated any bacteria from petrifilm, I wouldn't call this practice ideal, but I think it can work in a pinch. Some disadvantages I could see:
- If the original sample isn't diluted enough it will be difficult to sample an isolated colony.
- On APC film in particular, you can't be certain of how many different types of bacteria you're growing. You'll be growing multiple types of bacteria and they all look the same on the film.
- The E.coli/Coliform petrifilm carries the warning that EcoliO157 will not actually create a positive E.coli result on the plate. If you're concerned with identifying O157 specifically, you should consider a different approach
The 3M APC/ECC petrifilm instructions do indicate that isolated colonies can be removed for further identification. This is done by gently lifting the film and sampling a colony with a sterile loop, then streaking it onto a growth media. From there you could grow a culture and do gram staining or other identification tests. I've never personally isolated any bacteria from petrifilm, I wouldn't call this practice ideal, but I think it can work in a pinch. Some disadvantages I could see:
- If the original sample isn't diluted enough it will be difficult to sample an isolated colony.
- On APC film in particular, you can't be certain of how many different types of bacteria you're growing. You'll be growing multiple types of bacteria and they all look the same on the film.
- The E.coli/Coliform petrifilm carries the warning that EcoliO157 will not actually create a positive E.coli result on the plate. If you're concerned with identifying O157 specifically, you should consider a different approach
Brothbro, I appreciate the response. I was not looking for anything in particular. Just was wondering if there was identification guides from the past that were applicable. Your methods sounds reasonable and may be worth a shot if something strange does pop up in the future, but we have been good on our swabs so far (knock on wood).
Ah, got it now
You can't do that in house . Best thing to do is send your swabs off to a lab----they may be able to use the petri film plate, but you'd have to call and ask
The 3M plates are very specific and only tailored to a colony count
I use to identify all coliforms with API strips. it has its limitations, but is pretty easy to do. . I see the benefit, but its pretty time consuming. They have one for staph as well.
is this look like what you are looking for:
Typing of your bugs can be a very expensive process. External labs can do this for you but I'd only ever do this if you were having issues with your product. We've had to this where we kept getting high counts on moulds but didn't know their source. Typing helped to identify the species so we could understand where it was coming from and how we could manage it (if at all as was the case in one incidence.) There are some resources available that can help you identify the microorganisms by morphology, but that's not exact either and you'd need to be able to do other tests eg gram staining to determine +/- etc. It's outside the scope and abilities of most inhouse labs and you'd need to defer to professional microbiological laboratories.
Thank you all for the responses! I understand now that there is not a true way to identify things that have popped up in the past. There is no current concern, and hopefully none coming either. :thumbup: