Identifying microorganisms in normally sterile body fluids
Screening sputum specimens for acceptability for bacterial culture
Guiding initial antimicrobial therapy
See Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology in Special Instructions.
Conventional Gram Stain Procedure
Gram Stain
See Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology in Special Instructions.
Varies
Question ID | Description | Answers |
---|---|---|
Q00M0029 | Specimen Source |
Sources: Closed/open abscess, lower respiratory, fluid, tissue, or swab
Supplies: Culturette (BBL Culture Swab) (T092)
Container/Tube: Sterile container or culture transport swab (Dacron or rayon swab with aluminum or plastic shaft with either Stuart or Amies liquid medium)
Specimen Volume: Entire collection
Acceptable:
Slides: Prepared microscope slide
Collection Container/Tube: Sterile container or culture transport swab
Submission Container/Tube: Slide container
Collection Instructions: Apply original sample to surface of standard microscope slide using appropriate application method (determined by consistency of specimen type) to assure adequate transfer of specimen onto slide. Allow specimen to dry and then heat-fix the slide. Place in slide container for transport.
Swab/Other | Blood, stool, vaginal/cervical secretions, throat, or nasal specimen |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Varies | Refrigerated (preferred) | 24 hours | |
Ambient | 24 hours |
Identifying microorganisms in normally sterile body fluids
Screening sputum specimens for acceptability for bacterial culture
Guiding initial antimicrobial therapy
See Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology in Special Instructions.
The Gram stain is a general stain used extensively in microbiology for the preliminary differentiation of microbiological organisms. The Gram stain is one of the simplest, least expensive, and most useful of the rapid methods used to identify and classify bacteria.
The Gram stain is used to provide preliminary information concerning the type of organisms present directly from clinical specimens or from growth on culture plates. This stain is used to identify the presence of microorganisms in normally sterile body fluids (cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal fluid). It is also used to screen sputum specimens to establish acceptability for bacterial culture (<25 squamous epithelial cells per field is considered an acceptable specimen for culture) and may reveal the causative organism in bacterial pneumonia.
No organisms seen or descriptive report of observations.
During the staining process, the crystal violet and iodine form a complex within the heat fixed cell. In gram-negative organisms, this complex is readily washed out by the acetone-alcohol. They appear red because they retain only the safranin dye (counterstain). Gram-positive organisms retain the crystal violet-iodine complex after decolorization and remain purple.
Cells and Organisms will be reported according to the following tables:
| White Blood Cells Epithelial Cells | | Organisms | |||
Low Power Field (LPF-10x) | Rare (R) | < or =1 | Oil Immersion Field (OIF-100x) | Rare (R) | <1 | |
Few (F) | 1-9 | Few (F) | 1-5 | |||
Moderate (O) | 10-25 | Moderate (O) | 6-30 | |||
Many (M) | >25 | Many (M) | >30 |
Over-decolorization may result in the loss of the crystal violet iodine complex from gram-positive organisms and result in a misinterpretation.
Atlas R, Snyder J: Reagents, stains, and media: bacteriology. In Manual of Clinical Microbiology. Vol 1. 12th edition, Edited by KC Carroll, MA Pfaller. Washington DC, ASM Press, 2019, pp 331-361
The specimen is applied directly to the slide or may be concentrated first by centrifugation or cytocentrifugation and then placed on the slide. The slide is stained with crystal violet, stained with Gram iodine solution, decolorized with acetone-alcohol, counterstained with safranin stain, and blotted dry. The slide is examined using the oil immersion objective on the microscope.(Chan WW: Gram Stain. In Clinical Microbiology Procedures Handbook. Vol 1. Fourth edition. Edited by AL Leber. Washington, DC, ASM Press, 2016. Section 3.2.1)
Monday through Sunday
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
87205
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
GRAM | Gram Stain | 664-3 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
GRAM | Gram Stain | 664-3 |