There are several reasons why mycobacterial culture should now be confined to a minimal number of laboratories in a region or even a country.
- Safety: Samples for mycobacterial culture should be processed in a PC3 laboratory. Anything less is second best. Given the infrastructure, monitoring and quality control checks required for this type of facility, it makes sense to have as few of them as possible.
- Skills: Mycobacterial culture and the accompanying specimen decontamination measures is something which requires a considerable degree of operator expertise. It is preferable that any staff doing mycobacterial culture should be doing a lot of it.
- Turnaround time: When we are dealing with a test that has a turnaround time of weeks, not days, then a day “wasted” in transport of the specimen will make negligible difference to the clinical outcome.
- Extra testing: The positive mycobacterial culture samples will require extra testing, such as PCR, susceptibility testing etc. In order to be doing sufficient volumes of these tests to ensure quality, you need a lot of samples in the first place.
- Minimising cross contamination: A false positive Mycobacterium tuberculosis due to sample cross contamination is a much feared risk facing any mycobacterial laboratory. It is very difficult to reduce this risk to zero. However by having automated “closed system” culture technologies along with the skill base and experience of a large mycobacterial culture lab, this risk can be minimised.
- Cost Effectiveness: For a national funding body, it makes a lot of sense for mycobacterial culture work to processed in as few as possible sites, with the usual laws of volume processing applicable.
The days of microbiology laboratories processing 2-3 samples a week for mycobacterial culture should be long gone. If not, then why not?
In fact it is my belief that even laboratories processing 10-20 samples a week for mycobacterial culture should also be taking a long hard look at the justification in this, and asking. “Is this really in the best interests of our patients?