bacteria contamination - what can I do? (Jun/11/2008 )
What’s the highest concentration of Penicillin-Streptomycin you have ever use without problems???
I have a low passage line (the only culture in the lab) and they get contaminated with bacteria.
I’m using penic-strept and change medium everyday with no success. There are not a lot of bacteria, but they are there, what can I do????
Please, help!!!
What concentrations are you using and what are the bacterial contaminants?
also - about your motto
"Education does not make you necesarilly good, but it makes you potencially better."
The word is "potentially"
also - about your motto
"Education does not make you necesarilly good, but it makes you potencially better."
The word is "potentially"
And the other word is "necessarily".
..
I’m using:
1 X of Penicillin-Streptomycin 100 X from sigma (Formulated to contain 10,000 units/ml penicillin and 10 mg/ml streptomycin).
There are very few bacteria and they look like very tiny dots moving very quickly.
It’s important to save these cells, because it’s the only one we have!!!
Bye the way, Thanks for the correction, English is not my native language and I do many mistakes as you can see. 
1 X of Penicillin-Streptomycin 100 X from sigma (Formulated to contain 10,000 units/ml penicillin and 10 mg/ml streptomycin).
There are very few bacteria and they look like very tiny dots moving very quickly.
It's important to save these cells, because it's the only one we have!!!
Bye the way, Thanks for the correction, English is not my native language and I do many mistakes as you can see.
Bye
It will depend on what is the highest concentration your cells can survive on. You can do a killing curve by adding low levels of antibiotics, right up to concentrated levels to determine wheter your cells can survive or not. Watch out for cellular toxicity (such as vacuole formation and granules).
I did a killing curve with the antibiotics that you had mentioned and my cells survived without obvious signs of toxicity at a concentration of 5x. It will also depend on wheter the bacteria you are dealing with are resistant towards these treatments.
The best way is to throw the cells away because contamination is REALLY hard to cure.
But if these cells are rare, try curing them with antibiotics for at least 2 weeks.
I did a killing curve with the antibiotics that you had mentioned and my cells survived without obvious signs of toxicity at a concentration of 5x. It will also depend on wheter the bacteria you are dealing with are resistant towards these treatments.
The best way is to throw the cells away because contamination is REALLY hard to cure.
But if these cells are rare, try curing them with antibiotics for at least 2 weeks.
Thanks for the advice, definitively I will try to save them because it’s not a commercial line and as I told you, it’s the only we have.
I will try the toxicity curve and chance medium every day with media+antibiotic.
Wish me luck!!
I did a killing curve with the antibiotics that you had mentioned and my cells survived without obvious signs of toxicity at a concentration of 5x. It will also depend on wheter the bacteria you are dealing with are resistant towards these treatments.
The best way is to throw the cells away because contamination is REALLY hard to cure.
But if these cells are rare, try curing them with antibiotics for at least 2 weeks.
Thanks for the advice, definitively I will try to save them because it's not a commercial line and as I told you, it's the only we have.
I will try the toxicity curve and chance medium every day with media+antibiotic.
Wish me luck!!
I am wondering if in addition to doing this, if you can pass your cell culture through nylon mesh that has pore size smaller than your cells (always bigger than bacteria), wash multiple times with sterile PBS and antibiotic media, and then do the above high Antibiotic procedure.
Of course bacteria may have bound to/entered the cells and will stay put, but the bacterial load can be reduced to begin with. Also, you may do brief centrifugation and wash multiple times to get the same results.
My cells finally …. Passed away 
I haven’t find the way to say it to the PI
I haven’t find the way to say it to the PI
I lost my first PhD because of bacteria contamination in my primary culture. now I am doing my second PhD somewhere else. so you are not the unluckiest person on earth.
those bacteria are resistant to everything. even cocktail antibiotic, no one has ever made a good method for decontamination. but if you wash the cells well and hit the flasks hard on the side of laminar flow you must get rid of a lot of bacteria. you will lose some cells too, but most of the bacteria will get washed off. so you can sort of rescue the cells for some more time.