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The Manual of Clinical Microbiology Procedures Handbook (second edition 2004, available from ASM Press) offers two methods of preparing Gram stain quality control slides:
Prepare faintly turbid broth cultures of E. coli 25922 and S. aureus 25923. (These are QC strains that you may already have if you are doing antimicrobial susceptibility testing).
Place a drop of each on a slide, and spread the two drops into circles about 10 mm or the size of a dime. Allow to air dry, fix in methanol and store at -20 degrees C.
Alternatively with a toothpick or sterile applicator stick, procure material from between the teeth and apply to the end of slide used for specimen, separating this area with a marker. This method provides a built-in control with gram-positive and gram-negative representatives.
Bailey and Scott’s Diagnostic Microbiology (Baron, E. J. et. al, ninth edition, 1994) suggests a third option:
Prepare a suspension of mixed Streptococcus pyogenes ATCC 19615 and E. coli ATCC 25922 in saline. Place a thin drop on the surface of a slide and allow to air dry. These can be stored indefinitely at room temperature in a covered box. Fix and stain the smear in the same manner as the test slides.
Most basic microbiology textbooks also have procedures for quality control of the Gram Stain. It sounds as though you may be concerned about having viable organisms on the QC slide. These QC organisms can be safely handled in a Biosafety Level 2 laboratory. Information on biosafety levels is available on the CDC website in the BMBL (Biosafety in Microbiology and Biomedical Laboratories) at
http://www.cdc.gov/od/ohs/biosfty/biosfty.htm
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