Blood cultures and specimens: technique and sequence
A contaminated blood culture leads to an antibiotic that was not needed, extra days in hospital and a line that gets removed for nothing. The technique is the whole test. Before the antibiotic, always, when the clinical situation allows it. Once the first dose is in, the yield falls and the result may no longer be interpretable. Two sets from two separate sites, drawn at the same time in suspected sepsis. Two sets are what allow a true pathogen to be distinguished from a skin contaminant. Disinfect the skin and let it dry for the full contact time. Disinfect the bottle tops as well; this step is the one most often skipped. Do not touch the site again after disinfection. Fill the bottles to the marked volume. Underfilling is the leading cause of a false negative, and the volume matters more than any other variable. Urine culture: midstream after cleansing, or from the sampling port of an indwelling catheter, never from the drainage bag. Send it promptly or refrigerate it; a specimen left at room temperature grows organisms that were not in the bladder. Label every specimen at the bedside, in front of the client, before leaving the room.