Canis ISSN: 2398-2942

Staining techniques: Gram stain

Synonym(s): gram

Contributor(s): Kathleen P Freeman, Karen Gerber

Introduction

  • Gram-positive bacteria retain the crystal violet - iodine complex and stain purple-blue (cell wall prevents elution of violet by solvent).
  • Gram-negative bacteria are decolorized and are stained red by the counter-stain Stain: Gram.

Uses

  • Preliminary method of identifying bacteria by light microscopy together with morphological features, to implement appropriate antibiotic therapy, before culture results (48 h).

Advantages

  • Quick.
  • Good sensitivity.

Disadvantages

  • Poor specificity - other material in preparation, eg cells, also stain gram-negative.

Requirements

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Procedure

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Quin P J et al (1994) Clinical Veterinary Microbiology. Mosby. pp 21-22.
  • Pratt P W Laboratory Procedures For Veterinary Technicians. Third Edition. Mosby. pp 168, 169, 172.


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