Lab Test

Stain, Gram

Gram Stain

Test Codes





Gram stain is included with most orderable cultures. Please refer to individual test pages in the Lab Test Directory for information on specific types of cultures.

Specimen Collection Criteria

  • Tissue or fluid is the preferred specimen for Gram stain.
  • Specimens submitted on swabs should be submitted in the ESwab collection system.

Physician Office/Draw Specimen Preparation

  • Specimen handling should be appropriate for the specimen source submitted.
  • Swab transport collection systems should be maintained at room temperature (20-26°C or 68-78.8°F) until transport.
  • With the exception of CSF, specimens submitted in sterile containers should be maintained refrigerated (2-8°C or 36-46°F) prior to transport.
  • For optimal results, smears should be prepared by the Laboratory.

Preparation for Courier Transport

Transport: Swab specimen, at room temperature (20-26°C or 68-78.8°F), or specimen in a sterile collection container (with the exception of CSF), refrigerated (2-8°C or 36-46°F).

Rejection Criteria

  • Specimens delayed in transit.
  • Grossly contaminated specimens
  • Dessicated material.

Inpatient Specimen Preparation

Deliver specimens to the Laboratory immediately after collection.


Specimen stability and storage varies dependent on specimen type. Please refer to the individual test pages in the Lab Test Directory for information.


Dearborn Microbiology Laboratory
Taylor, Trenton and Wayne sent to Dearborn Microbiology Laboratory for testing.

Farmington Hills Microbiology Laboratory
Grosse Pointe Microbiology Laboratory
Royal Oak Microbiology Laboratory
Troy Microbiology Laboratory


Sunday – Saturday, 24 hours a day.
Routine results are reported within 8 hours of receipt in the Laboratory.

STAT results are reported within 1 hour of receipt in the Laboratory.

STAT results will be called, if requested or if on the Critical Call List.

Reference Range

For sterile site specimens, no organisms seen. For non-sterile specimens, Gram stain results are dependent on the morphology and Gram reaction of organisms and amount of inflammation present.

Test Methodology

Microscopic examination of a stained specimen.


Gram positive or negative, rod or coccus. It can provide rapid presumptive diagnosis of infectious agents and also be used to assess the quality of clinical specimens.

Clinical Utility

The Gram stain is the most basic stain in bacteriology, delineating major structural and taxonomic groups of organisms.


  1. Chan, W.W., 2016. Staining Procedures: Gram Stain. Clinical Microbiology Procedures Manual. 4th ed. Leber, A.L., Editor-in-Chief (ed). ASM Press, Washington, D.C

CPT Codes



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