Types of chromatography in diagnostics
A whole spectrum of chromatographic approaches is used in laboratory practice. Among them:
- Gas-liquid chromatography (GLC) — the main tool for searching for volatile compounds.
- High-performance liquid chromatography.
- Gas chromatography.
- Thin-layer chromatography.
Each of these options aims to separate complex mixtures of substances present in biological material, but GLC in particular has found widespread application in routine rapid diagnostics of specific infections.
Gas-liquid chromatography (GLC)
This method has become the gold standard for rapid diagnosis of anaerobic infection.
The principle of action is based on the chromatographic detection of specific bacterial metabolic products directly in the studied material. During their life cycle, microorganisms release certain substances that can be detected instrumentally.
The main metabolic markers of the presence of anaerobes are volatile fatty acids. By detecting them in a sample using GLC, a clinical microbiologist can confirm the presence of anaerobic flora with a high degree of confidence without waiting for the results of a prolonged culture assay.
Rapid laser-fluorescence method
An alternative physicochemical approach relies on the optical properties of biological objects. The principle of the method includes three key stages:
- Irradiation of the clinical material with a directed laser beam.
- Recording the intrinsic fluorescence (so-called autofluorescence) of the studied material.
- Analysis of the emission spectrum. This spectrum is considered unique for most known microbes, as well as for their metabolic products.
The method is actively used for purulent-inflammatory diseases and various dysbioses. It is of particular value in dental pathology, helping in the diagnosis of dental caries and periodontitis. In addition, fluorescence evaluation is used to predict the effectiveness of prescribed treatment.
Despite its technological advancement, the method has a significant drawback — low specificity. The device records luminescence, but is not always able to accurately differentiate closely related species of microorganisms (unlike methods aimed at strict pathogen identification, viral load determination, or classical antibiotic susceptibility testing).
To memorize GLC markers: "Anaerobes Fly with Fatty Acids" (VFA — volatile fatty acids).
Class and exam questions
What is gas-liquid chromatography primarily used for?
GLC is used for the rapid diagnosis of anaerobic infection by detecting volatile fatty acids in the material.
What is the principle of the laser-fluorescence method based on?
Based on laser irradiation of the material and subsequent recording of the unique spectrum of the microbes' intrinsic autofluorescence.
What is the main disadvantage of laser fluorescence?
The method has low specificity, which limits its application for the precise identification of a specific pathogen.
What else to study on this topic
- High-performance liquid chromatography (HPLC)
- Gas and thin-layer chromatography: differences from GLC
- Methods for assessing bacterial antibiotic susceptibility
- Approaches to pathogen identification and viral load determination
Study the full topic in the «Microbiology» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Physicochemical diagnostic methods" and 4,383 other subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 141 video lectures on the subject
Other topics in the section "Microbiological diagnostics"
Free video lessons: microbiologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.