Microbiological diagnostics: objects of study and stages
The diagnosis of mycotoxicoses is based on the indication of molds or the detection of their metabolic products — mycotoxins.
In laboratory practice, specialists collect the following as test material:
- Various harvested crops.
- Food products intended for human consumption.
- Agricultural feed.
- Various raw materials of animal origin.
The laboratory testing process itself is strictly regulated and divided into two key stages. The first stage involves the extraction of the mycotoxin from the collected sample. Organic solvents are used for this process in laboratories. Following successful extraction, the second stage begins — the direct identification of the isolated toxin using specialized methods.
Methods of mycotoxin identification
After extracting the toxin from the substrate, it is necessary to accurately determine its nature. A set of laboratory methods is used for this, divided into three major groups:
- Physicochemical methods. They form the basis of instrumental detection. These include various modifications of chromatography and spectrophotometry.
- Biological methods (bioassays). This approach allows assessing the toxicity of the isolated material on living test objects. Such objects include:
- Chicken embryos.
- Isolated cell cultures.
- Laboratory animals (white mice, rats, guinea pigs).
- Birds (most commonly ducklings and pigeons).
- Sensitive microorganism strains.
- Immunological methods. Based on specific antigen-antibody reactions. This group includes radioimmunoassay (RIA) and the widely used enzyme-linked immunosorbent assay (ELISA).
Principles of therapy in mycotoxicoses
Treatment measures for fungal metabolite poisoning have clear clinical frameworks. It is important to note that the nature of treatment is exclusively symptomatic.
The main focus of therapy is immediate detoxification of the body. To rapidly remove toxic substances from the digestive tract and systemic circulation, the following procedures are performed:
- Thorough gastric lavage.
- Artificial bowel cleansing.
- Other available medical measures aimed at the forced elimination of mycotoxins from the victim's body.
Prevention and sanitary control
Preventing the development of mycotoxicoses is significantly easier than treating their consequences. The basis of safety is primary prevention. Its main task is to prevent the initial contamination of food products and feed with mold spores, as well as to inhibit their reproduction and toxin production.
The second critical level of protection is strict sanitary control, which includes:
- Mandatory laboratory testing of all suspicious products for toxicity.
- Strict compliance with established maximum residue limits (MRLs) for various types of mycotoxins.
The global target indicator of all preventive measures is ensuring the complete absence of mycotoxins in human food and animal feed.
Briefly: answers to topical questions
Which species of mold fungi are the main producers of mycotoxins?
The main producers of mycotoxins indicated in the sources are microscopic fungi of the genera Aspergillus, Penicillium, Fusarium, and Claviceps.
- Genus Aspergillus — produces aflatoxins; various Aspergillus species also produce ochratoxins, patulin, gliotoxin, sterigmatocystin, tremorgens, cytochalasins, and citrinin.
- Genus Penicillium (P. citreoviridae, P. islandicum) — associated with mycotoxicosis from consuming "yellow rice".
- Genus Fusarium (F. sporotrichiella, F. graminearum) — causes mycotoxicoses: alimentary-toxic aleukia and "drunken bread" syndrome.
- Species Claviceps purpurea — infects rye and produces toxic ergot alkaloids: ergotoxin, ergotamine, ergometrine.
What clinical symptoms and syndromes are characteristic of acute mycotoxicoses?
Clinical manifestations of mycotoxicoses indicated in the sources depend on the specific form.
- Ergotism — occurs in convulsive and gangrenous forms; ergot alkaloids cause a hallucinogenic effect and affect the vascular system of the lower extremities.
- Alimentary-toxic aleukia — associated with the consumption of bread made from overwintered field grains infected with Fusarium fungi; initially, a sharp disruption of hematopoiesis occurs, followed by an acute septic state with toxic angina and skin hemorrhages.
- "Drunken bread" syndrome/poisoning — accompanied by central nervous system damage and impaired coordination; euphoria, laughter, singing, agitation are described, followed by depression and exhaustion.
- Aflatoxins — possess pronounced hepatotoxicity and carcinogenic effects, causing gastrointestinal tumors.
For quick memorization of mycotoxin identification methods, use the acronym PIB: Physicochemical, Immunological, Biological (bioassays).
Class and exam questions
Is etiotropic therapy used for mycotoxicoses?
No, therapy is exclusively symptomatic. The main task of doctors is to perform detoxification (gastric lavage, bowel cleansing) and eliminate symptoms of damage.
What subjects are used for bioassays?
For biological identification methods, chicken embryos, cell cultures, laboratory rodents (mice, rats, guinea pigs), birds (ducklings, pigeons), and sensitive microorganisms are used.
Why are organic solvents needed in diagnostics?
Organic solvents are required at the first stage of laboratory testing. They are used for the extraction of mycotoxins from feed, food, or raw material samples for subsequent analysis.
What else to study on this topic
- Mechanisms of chromatography and spectrophotometry in mycotoxin detection
- Principles of ELISA and RIA assays in microbiological diagnostics
- Features of mold growth and conditions for their toxin production
- MRL standards for mycotoxins in the food industry
- Specifics of conducting bioassays on chicken embryos
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 "Diagnostics, Treatment, and Prevention of Mycotoxicoses" and 4,383 more pages of the subject
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