Contamination of Solutions
- Contamination of the staining solutions occurs rarely but should be suspected when smears repeatedly contain the same organisms, and these organisms do not grow upon culture or are inconsistent with the clinical picture.
- Yeast and gram-negative bacilli are the most frequently identified stain contaminants, although gram-positive organisms may also cause concern.
- Contamination may also occur whenever aliquots of solution are transferred from a large stain container into smaller (reused) bottles, or when piped deionized water used in automated stainers becomes contaminated.
Contamination of Slides
- The use of glass slides that have not been precleaned can also be a cause of contamination. Frosted-end slides may be prepared in a container of 95% ethanol (reminder: change alcohol solution daily); use forceps to lift the slide and drain the alcohol. (Safety note: Drain and air dry before heat-fixing the slide.)
- Containers holding immersion oil may also become contaminated. The use of disposable droppers may be helpful.
