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Antibiotics and infection - (Jun/02/2006 )

Hello everyone,

I have iniciated a cell culture in which accidentaly I added antibiotic (I didn't want to add antibiotic because these cells are to be infected with bacteria). I left the cells overnight and then I changed the medium again but this time with no antibiotic.

Can I still infect these cells? How long must I wait until the antibiotic has no longer effect?

Thanks in advance.


I can only tell you what I know from my own experience with primary keratinocytes

we do various types of infection assays with bacteria. we propagate and maintain cultures with antibiotic always. 24-48 hours prior to the infection protocol, we change the medium with a brief PBS rinse in between (just like any other time we feed the cells) but we do not add antibiotic into this fresh medium. the next day we do the infection, and the bacteria are not harmed

just like with your cells, I would think; you metabolize the antibiotics in a relatively short time and they are gone...if they are never ingested, then I suppose it's just a matter of rinsing them away and out of the medium

so as long as you have some time for the cells to grow with no antibiotic prior to infecting them, then you should be fine I think.


The old adage is IF IN DOUBT CHUCK THEM OUT. If your cells are stable lines then go back to the original stock. If your aseptic technique is good enough you should NEVER use antibiotics anyway.
If people feel the need to use pen/strep/gentamycin etc, you should on a routine basis look for Cryptic contamination ie. culture in the absence of antibiotics.


jsut one night is relatively secure regarding bacterias.
What i do for infection procedure, is a wash of cells by antibiotic-free medium and add the infection liquid on them.
so i guess it's ok.