Delayed processing of blood samples influences time to positivity of blood cultures and results of Gram stain-acridine orange leukocyte Cytospin test.

We investigated in vitro whether storage of blood samples influences the time to positivity used for the calculation of the differential time to positivity (DTP) and the results of the Gram stain-acridine orange leukocyte Cytospin (AOLC) test. A 24-hour storage of blood samples at room temperature may lead to false-negative DTP and false-positive Gram stain-AOLC test results, whereas storage at 4 degrees C does not.