Proper reading of cultures: still important
As I cannot stay away from the Micro lab, even on the weekend, I made my Saturday morning pilgrimage to make sure nothing was amiss. I did find two things of note: first, even though there was a practical question dealing with the proper discarding of cultures that essentially everyone got correct, in practice people seem to miss what the proper procedure is. All to-be-discarded culture tube need to go in the appropriate rack, with all tape removed prior to discard. Second, I found about a dozen cultures in the incubator. Those of you who left cultures in the incubator for the weekend will need to run them again. I do feel somewhat like a broken record in this regard, as I did specifically state it to everyone repeatedly on Wednesday and Thursday, and wrote about it here previously, but perhaps it is time to reemphasize things that are important for success in a lab.
All of our cultures need to be run, incubated, and interpreted according to specific guidelines, or else the interpretation of the culture is completely invalid. The Clinical and Laboratory Standards Institute is a national organization that establishes guidelines for the proper way to set up and read clinical assays in laboratories. If a test is run for too short of an interval, there is a significant possibility of obtaining a false negative result, and if a test is run for too long of an interval, there is a possibility of obtaining a false positive result. Either case represents the possibility of a poor patient outcome: for the false negative, they might not receive notice that they have a given infection, and for the false positive, they might be started on an inappropriate treatment regimen.