It depends on the storage temperature. Check these papers

http://www.ncbi.nlm.nih.gov/pubmed/10751076

and

http://www.ncbi.nlm.nih.gov/pubmed/16499256 for MGIT liquid culture. Although the latter seems overly optimistic to me. There is a practice of storing decontaminated sediments at 4° up to 10 days before culture, but I am unaware of clear data on this.

a recent paper for this topic.

http://jcm.asm.org/content/early/2013/01/17/JCM.02751-12.full.pdf

M .tuberculosis has a very slow growth so, it needs to a long time (4-6)weeks on Löwenstein-Jensen medium to grow. although,with using specific medium(bactec system) ,detection of growth time is shorter.

M. tuberculosis and other slow growth mycobacteria needs 5-7 weeks to grow (Loweenstein-Jensen) or 4-5 weeks (liquid medium). The time to detect grow is closely connected with the number of bacilli inoculated on the medium.

It depends on the storage temperature. Check these papers

http://www.ncbi.nlm.nih.gov/pubmed/10751076

and

http://www.ncbi.nlm.nih.gov/pubmed/16499256 for MGIT liquid culture. Although the latter seems overly optimistic to me. There is a practice of storing decontaminated sediments at 4° up to 10 days before culture, but I am unaware of clear data on this.

May be one week if bacilli 1+ are present and if you can preserve in 1 % cetyl pyridine for time to increased for culture of mycobacteria

now a day DNA based newer tech(line probe assay). available for detection of M .tuberculosis as well as resistant of Rifampicin and isoniazid at same day

Dear all, thanks for all responses. Althoug I would like to highlight that I am not asking how much time it takes to do a M.Tuberculosis culture, I am asking how much you can wait till you start processing the sample without having a negative impact on the viability of the bacili.

There are two issues, one is the increase of other bacteria (contaminants) and the other is reduction in the yield. It is recommended to refrigerate (do not freeze) sputum samples as soon as possible after collection to reduce multiplication of other bacteria (fast growers). The yield starts reducing by ten folds at 2-80c after 7 days. The earlier you process after collection the better.

@Norbert Heinrich

I agree about refrigerated storage and the fact of 10days storage.

It depends to time storage and decontamination method as well

There is no specific cutoff. As quick as possible process always gives good result. For delayed process refer Mr. Saurabh Gayli article.

That is correct mr balaji

The sample collection should be sterile container and must be kept at low temperature after collection to avoid other contaminants.