Textual Amendments
Check the positive control slide first. Cells must be bright fluorescent and completely stained at the determined antibody titre or working dilution. The IF test (Section VI.A.5.) must be repeated if the staining is aberrant.
If any contamination is suspected the test must be repeated. This may be the case when all slides in a batch show positive cells due to the contamination of buffer or if positive cells are found (outside of the slide windows) on the slide coating.
If bright fluorescing cells with characteristic morphology are found, estimate the average number of typical cells per microscope field and calculate the number of typical cells per ml of resuspended pellet (Appendix 5).
The IF reading is positive for samples with at least 5 × 10 3 typical cells per ml of resuspended pellet. The sample is considered potentially contaminated and further testing is required.
The IF reading is negative for samples with less than 5 × 10 3 cells per ml of resuspended pellet and the sample is considered negative. Further testing is not required.]