DOC-00322-ENA.doc Page 20 of 29 ! Wescor, Inc
Reagent precipitate or foreign matter inside the nozzle typically causes low volume from a spray nozzle. If the
CLEAN cycle does not help, the best solution is to manually disassemble and clean the spray nozzle.
Excessive Volume
If collecting excessive volume, make sure the nozzle is assembled correctly (see Reassembly in Section 6o). If this
fails to correct the problem, contact an authorized representative or Wescor for assistance.
k. Special Equipment Required (8.7e)
See the list of Accessories in Section 6c for the maintenance tools and supplies provided with each stainer.
l. Type of Specimen to be Used (8.7f)
The equipment is used to stain acid fast bacteria specimens that are applied to microscope slides. The stainer allows
selection of stain applications on a scale of 1 to 6. The chart below shows recommended settings for various specimens.
For best results, separate your slides according to smear thickness, and load specimens of similar thickness in the same
carousel. Specimens should be prepared as thinly as possible. If prepared as thin smears, most specimens can be stained
satisfactorily on settings 3 or 4.
NOTE: These are suggested settings only. Each laboratory should establish its own protocol for staining.
INSTRUMENT
SETTING
THICKNESS
1
THIN SPECIMEN
2
3 MEDIUM SPECIMEN
4
5
6 THICK SPECIMEN
Over-decolorization
Over-decolorization occurs when acid fast bacteria positives are incompletely stained or when the decolorizer removes
the stain from the cells to make them appear negative. Possible causes include:
a. Low or primary stain application
Check the reagent delivery system (reagent levels, spray volume, spray pattern and solenoid function).
b. Incorrect decolorizer preparation
Use SS-061A for the carbol fuchsin stains and SS-061AF for fluorescence stains. Check decolorizer to assure
proper composition if made from concentrate.
c. Stain setting too high
Decolorization is increased as the stain setting is increased. Use the lowest setting that yields proper staining.
Under-Decolorization
Insufficient decolorization of specimens results in a partially acid fast positive appearance in the smear’s AFB negative
bacteria, due to incomplete removal of the primary stain. Possible causes include:
a. Inadequate decolorizer application
Improper spray pattern or volume delivery from the decolorizer nozzle causes poor decolorization. Check the
level in the decolorizer bottle, and check for air in the decolorizer line. Verify nozzle performance.
b. Thick smears
Smears that are excessively thick, can contribute to under-decolorization due to incomplete penetration of the
water wash and decolorizer reagents. In general, try to make smears as thin as possible. If necessary, increase
the stain setting for thick specimens.
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