The precise diagnosis of a fungal infection is of great importance for treatment. It is necessary to identify the pathogen in order to tailor the treatment accordingly. The medical history and physical examination are therefore often followed by laboratory tests.
Here you will find further information and selected fungal diagnostics specialists.
Numerous fungal diseases can affect humans. Most fungal diseases occur locally and superficially on the skin. Sometimes, however, organs are also affected. Depending on the exact type of fungal disease, different therapies are required to combat it. It is therefore important to precisely determine the pathogen by means of careful fungal diagnostics.
Medical fungal diagnostics always includes a medical history (patient interview) and a physical examination. If the diagnosis is unclear, a laboratory examination of a tissue sample and the cultivation of a fungal culture are also carried out.
Anamnesis refers to the patient interview with the doctor. It is always at the beginning of a diagnosis. The doctor will ask you about
The medical history provides the doctor with important information about the disease in question.
The doctor will try to clarify factors that could indicate an immune deficiency. Fungal pathogens can settle more easily in people with a weak immune system. You can therefore expect questions about
For example, the doctor may be interested to know whether you suffer from the following illnesses:
Information on injuries of any kind can also be helpful for the doctor when diagnosing fungi. Pathogens can easily enter the body through injuries, even the smallest wounds. If you have recently had an open wound or injury, you should tell the doctor about it. Even a small cut would be significant here.
The doctor will also ask about past trips. These can also play a role. Some fungal diseases occur more frequently in certain latitudes. For example, fungi of the genus Coccidioides only occur in the desert regions of the American continent.
Recent trips to such regions and corresponding symptoms thus point to a specific pathogen.
In the case of a superficial infection, the symptoms and the infestation can usually be localized very quickly. The typical symptoms of a superficial fungal infection include
The pathogen can easily enter the body through skin injuries. In the worst case scenario, a systemic fungal disease develops.
A systemic fungal disease can manifest itself through high fever and malaise. However, symptoms only appear some time after infestation by the pathogen.
If the lungs are infected, severe shortness of breath occurs in most cases. If the symptoms do not subside after a few days, consult a doctor for clarification.
The next step if a fungal infection is suspected is a physical examination. This is a good way of diagnosing a superficial infection. The doctor, usually a dermatologist, takes a close look at the affected area.
Based on typical symptoms, he can often narrow down the pathogen causing the fungal disease. In the case of oropharyngeal candidiasis, for example, yellowish-white deposits can be seen on the mucous membrane in the mouth and throat.
In the case of systemic fungal disease, the examination is much more difficult. Shortly after the pathogen has settled, the systemic infection can hardly be distinguished from a bacterial infection. This often leads to misdiagnosis and delayed treatment.
In rare cases, the patient may even die from the fungal disease due to an incorrect assessment by the doctor. This makes the early diagnosis of a systemic infection a challenge.
Imaging procedures can be used to diagnose a systemic fungal disease. A computer tomography (CT) scan of the lungs or brain can show the presence of fungal disease.
This step is not necessary for every fungal disease. However, if the diagnosis is unclear, identifying the exact pathogen is very important for treatment.
The microscopic detection of a fungal pathogen initially involves confirming that a fungal disease is present at all. Under the microscope it can be seen whether a fungus or another disease is causing the symptoms.
The pathogen is then identified. This allows the doctor to tailor the medication precisely to this fungal infection.
For the microscopic examination, the doctor takes a tissue sample from the affected area. This is then examined under a microscope in the laboratory.
It is often necessary to grow a fungal culture from the sample in order to identify the pathogen. This allows the exact pathogen that caused the infection to be determined after a few days to several weeks.
In medical pathogen detection, a distinction is made between the fungal genera of
Pathogen detection using a microscope and cultivation of a fungal culture provides accurate results. These are the standard methods of fungal diagnostics.
Nowadays, molecular biological pathogen detection is also possible. This involves identifying specific gene segments of the respective fungal type. However, this is very cost-intensive and is therefore not yet part of routine diagnostics.
Direct pathogen detection in the case of a suspected fungal infection affecting the epidermis, nails or hair is carried out using a sample. This is taken under sterile conditions, for example with a wooden spatula.
If the fungus is located on the skin, the sample must be taken from the peripheral area of the infestation. This is usually the only place where living fungi can be found. These provide the most reliable sample material for successful pathogen detection. In the case of a possible nail fungus, the sample material is also taken from under the nail, as this is where the presence of living fungi is most likely.
A ring curette can be used to take the sample. This is a forceps-like instrument for taking tissue samples.
If hairy areas of skin are affected by mycosis, the doctor needs hair , including the hair root. Using tweezers, he pulls a few hairs from the affected area. The fungi multiply in the hair follicle. If only hairs are cut off, there is often no living and therefore usable sample material for pathogen detection.
The sample material is then placed on a slide with potassium hydroxide solution (15 to 20 percent). Potassium hydroxide solution is a highly alkaline, corrosive, aqueous solution of potassium hydroxide. It dissolves the fungal pathogens from the sample, such as a skin flake, within about 30 minutes.
The sample material should generally be stored moist to prevent the formation of crystals. Crystals would make pathogen detection more difficult or impossible.
When determining the pathogen, a 100x magnification is initially used. Only after a thorough examination is a 400x magnification used. At this magnification
can be recognized. If these are present, it is certain that a fungal disease is present.
The hyphae or spores can also be stained. This simplifies the detection of the pathogen. For this purpose, methylene blue is added to the potassium hydroxide solution as a dye.
Fluorescent dyes can also be used in combination with a fluorescence microscope. After staining a sample with a fluorescent dye, it is irradiated with light of a specific wavelength. As a result, the pathogens themselves begin to emit light.
Special filters are used in the microscope through which only the light emitted by the sample can be seen. This pattern can be used for pathogen detection.
However, microscopic examination of the sample cannot yet determine the species or genus of the pathogen. A fungal culture is required for this.
For a fungal culture, material from the tissue sample is grown on agar plates. These are nutrient-containing gel plates made from algae extracts.
Clean cultivation without foreign pathogens such as bacteria, yeasts or molds is necessary for clear pathogen detection. Inhibitors are used for this purpose and the laboratory environment should be sterile.
In some cases, dyes are also applied to the agar plates. They indicate specific metabolic products of individual fungal species through coloration. Accordingly, they can also be used to detect pathogens.
The samples must be incubated for two to three weeks at 28 to 30 degrees. Only in the case of so-called liquid cultures is around three days at 37 degrees usually sufficient for pathogen identification.
The fungal cultures have then developed to such an extent that it is possible to detect the pathogen under the microscope. The pathologist assesses the appearance of the culture. Certain growth characteristics of the sample already narrow down the possible pathogens.
The fungal pathogen can be precisely determined using a fungal culture © luchschenF | AdobeStock
The actual pathogen is detected under the microscope.
Once the sample culture has developed sufficiently after two to three weeks, the actual pathogen detection is carried out under the microscope in addition to an assessment of its appearance.
For this purpose, part of the cultivated dermatophyte culture is detached and placed on a slide with a staining solution. Methylene blue is usually used to stain the sample.
The specific arrangement of the fungal filaments, fruiting bodies and spores then enables species identification.
Another advantage of the fungal culture is that it can be used to test therapy options. This allows the effect of a medication to be tested without the patient having to take the medication.
A final determination of the pathogen can take several weeks due to the cultivation of a fungal culture.
In the case of systemic mycosis, however, rapid action is necessary to prevent the pathogen from spreading further. For this reason, treatment with antimycotics is often started even before the pathogen has been identified.
Broad-spectrum antimycotics are then usually used. These combat not just one pathogen, but several. Nevertheless, the treatment may not be effective as the specific pathogen is not detected.
Early fungal diagnostics and the creation of a fungal culture are therefore of great importance.
