I have a problem with weird contamination in my fibroblast culture for almost 2 months. I am doing cell culture almost 10 years so I recognize alliens in culture, current one is bacteria. However, this is a type I have never seen. If a culture contaminated, all flasks you feed at the same time contaminated. But mine is new fashion. Let me say what I mean. I did primary culture from mice, I frozen cells in clean condition at passage 1. Then I started to do some experiments and thawed a vial to a 96 well plate and a 6 well plate. Result: 6 well plate is contaminated, 96 well plate very nice. Then I thawed new one to 2 x T75 flasks. Result: one is contaminated. Then I thawed another one to 2 x T75 flasks and one 96 well plate. Result: 96 well plate is very fine, T75 flasks are contaminated. I used two different brands of flasks for subculture, both contaminated. I had another brand for the primary culture which was clean. All contaminations occur after 48 hours not 24 hours (I am used to see the day after contamination). OK my questions here if anyone can help:
1. Is that possible to have contaminated plastic ware (flasks) batch from different country's companies at the same time? (If anyone matematician or statistician can be more sure of the answer)
2. I put samples of DMEM, FBS, trypsin, pen-strep etc into incubator to incubate them for 3 days to see any turbiditiy. But I also think that take some amount of these samples spread onto agar plate and see bacteria culture is there?
Thanks for your answers in advance. Please HELP
P.S. I work very careful and clean. I wipe all things out with EtOH, sprayed hood and incubator, clean and changing water in bath etc.