Protocol Online logo
Top : Forum Archives: : Cell Biology

mycoplasma and fungus - tissue culture infection (Jul/07/2004 )

Hi all!
I'm trying to find out about fungul and mycoplasma contamination. The other day I gave some of my cells to a collegue who is studying fungus, as a negative control, yet my cells came up positive in his pcr. he seems quite certain that it's a not a false positive. My cells seem fine, and I can see no usual fungal "characteristics"- long filaments or lawns. However there are a few floating "objects" in the flasks- they are not of a regular shape, can form clumps, about a quarter of the size of my cells (so too big for bacteria). I can't figure out if they multiply at all, there seem to be a few at all times, with a small increase in number over time- but what I am not sure about is if they multiply or if some of my cells are dying and that's just debris. Can it be mycoplasma? Woudl I be able to see it under a microscope? Is there any way to treat this infection?
At the moment I'm adding 4 different antibiotics to these cultures, as they are transfectants and I'm keeping two plasmids, so the usual Pen/strep mixture, plus neomycin and hygromycin (that's why I was surprised to get an infection, if that's what it is, and also think that maybe my cells dye faster with all tese antibiotics).
Any comments please?


check out BM cyclin. can also try DAPI to stain extranuclear DNA. sometimes it is hard to see. you need a good microscope and maybe 63X objective.


You might be dealing with a Nocardia Asteroides or Mycobacterium gordonae contamination. Try supplementing with 5ug/ml of p-aminosalicylic acid or Isonicotinicacid hyrazide or ethambutol or D-cycloserine. These drugs should kill of the contaminant, yet not affect other species.