The page below is a sample from the LabCE course Reading and Reporting Gram Stained Direct Smears. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Reading and Reporting Gram Stained Direct Smears (online CE course) »
How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 97 CE courses, most popular
$95 Add to cart
Pick Your Courses
Up to 8 CE hours
$50 Add to cart
Individual course$20 Add to cart

Quality Control Smears

According to regulatory requirements, Gram stain quality control (QC) testing must be performed with each new batch of stain and at least weekly, using both gram-positive and gram-negative organisms. However, individual laboratories may have more stringent requirements. No matter what the required frequency for QC testing, if you prepare and read Gram stains infrequently it would be helpful to stain quality control slides at the same time as a patient Gram stain smear.

The image on the right represents control slides using Staphylococcus aureus as the gram-positive control and Escherichia coli as the gram-negative control.

  • If properly stained, the Staphylococcus aureus on the positive control slide (side A in the image) will stain blue, or gram-positive.
  • The Escherichia coli on the negative control slide (side B in the image) will stain red, or gram-negative.
  • If these slides are not stained properly, the problem must be resolved and new slides made before patient specimens are examined and reported.