An accurate diagnosis of a fungal infection is crucial for treatment. Identifying the pathogen is necessary to tailor the treatment accordingly. Therefore, a medical history and physical examination are often followed by laboratory tests.
Here you will find further information as well as a selection of specialists in fungal diagnostics.
Numerous fungal infections can affect humans. Most fungal infections occur locally and superficially on the skin. However, organs are sometimes affected as well. Depending on the specific type of fungal infection, different treatments are necessary to combat it. That is why it is important to precisely identify the pathogen through careful fungal diagnostics.
Medical fungal diagnostics always includes a medical history interview (patient consultation) and a physical examination. If the diagnosis is unclear, laboratory testing of a tissue sample and fungal culture are also performed.
Medical history refers to the discussion between the patient and the doctor. It is always the first step in the diagnostic process. During this discussion, the doctor will ask you about
The medical history provides the doctor with important clues about the condition at hand.
The doctor will try to identify factors that could indicate an immune deficiency. Fungal pathogens can take hold more easily in people with weakened immune systems. So expect questions about
For example, the doctor will be interested in knowing whether you have any of the following conditions:
Information about injuries of any kind can also be helpful to the doctor in diagnosing a fungal infection. Pathogens can easily enter the body through injuries, even the smallest wounds. If you’ve recently had an open wound or an injury, you should mention it to the doctor. Even a small cut could be significant in this context.
The doctor will also ask about past travel. This, too, can play a role. Some fungal infections occur more frequently at certain latitudes. For example, fungi of the genus Coccidioides are found only in the desert regions of the Americas.
Recent travel to such regions, along with corresponding symptoms, may thus point to a specific pathogen.
In the case of a superficial infection, the symptoms and the affected area can usually be pinpointed very quickly. Typical symptoms of a superficial fungal infection include
The pathogen can easily enter the body through skin lesions. In the worst-case scenario, this can lead to a systemic fungal infection.
A systemic fungal infection can manifest as a high fever and general malaise. However, symptoms do not appear until some time after infection with the pathogen.
In most cases, infection of the lungs leads to severe shortness of breath. If your symptoms do not subside after a few days, see a doctor to have them evaluated.
The next step if a fungal infection is suspected is a physical examination. This is an effective way to diagnose a superficial infection. During the examination, the doctor—usually a dermatologist—closely examines the affected area.
Based on typical symptoms, they can often narrow down the specific pathogen causing the fungal infection. For example, in oropharyngeal candidiasis, yellowish-whitish patches can be seen on the mucous membranes in the mouth and throat.
In the case of a systemic fungal infection, the examination is much more difficult. Shortly after the pathogen has taken hold, the systemic infection is virtually indistinguishable from a bacterial infection. This often leads to misdiagnoses and a delayed start to treatment.
In rare cases, the patient may even die from the fungal infection due to an incorrect assessment by the physician. This makes the early diagnosis of a systemic infection a challenge.
Imaging techniques are useful for diagnosing a systemic fungal infection. A computed tomography (CT) scan of the lungs or brain can reveal the presence of fungal infections.
This step is not necessary for every fungal infection. However, when the diagnosis is unclear, identifying the exact pathogen is very important for treatment.
Microscopic detection of a fungal pathogen first involves confirming that a fungal infection is present at all. Under the microscope, it is possible to determine whether a fungus or another condition is causing the symptoms.
This is followed by the identification of the specific pathogen. 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 sample is then examined under a microscope in the laboratory.
Often, culturing the fungal sample is necessary to identify the pathogen. This allows for the precise determination, after a few days to several weeks, of which pathogen caused the infection.
In medical pathogen detection, a distinction is made between the fungal genera of the
Pathogen detection using a microscope and fungal culture provides accurate results. These are the standard methods of fungal diagnostics.
In addition, molecular biological pathogen detection is now also possible. This method identifies specific gene segments of the respective fungal type. However, it is very costly and is therefore not yet part of routine diagnostic procedures.
Direct pathogen detection in cases of suspected fungal infection affecting the epidermis, nails, or hair is performed using a sample. This sample is collected under sterile conditions, for example, with a wooden spatula.
If the fungus is present on the skin, the sample must be taken from the outer edge of the affected area. This is typically the only place where live fungi can be found. These provide the most reliable sample material for successful pathogen detection. In cases of suspected nail fungus, the sample is also taken from under the nail, as this is where living fungi are most likely to be found.
A ring curette can be used for collection. This is a forceps-like instrument for collecting tissue samples.
If hairy areas of skin are affected by a fungal infection, the physician needs hair, including the hair root. Using tweezers, the physician pulls out a few hairs from the affected area. The fungi multiply in the hair follicle. If only cut hairs are collected, there is often no living—and therefore usable—sample material for pathogen detection.
The collected sample is then placed on a microscope slide containing potassium hydroxide solution (15 to 20 percent). Potassium hydroxide solution is a strongly alkaline, caustic, aqueous solution of potassium hydroxide. It extracts the fungal pathogens from the sample—such as a skin flake—within about 30 minutes.
The sample material should generally be stored in a moist environment to prevent the formation of crystals. Crystals would make pathogen detection difficult or impossible.
When identifying the pathogen, a 100x magnification is used initially. Only after a thorough examination is a 400x magnification applied. At this magnification,
be identified. If these are present, it is certain that a fungal infection is present.
The hyphae or spores can also be stained. This simplifies pathogen detection. For this purpose, methylene blue is added to the potassium hydroxide solution as a dye.
It is also possible to use fluorescent dyes in combination with a fluorescence microscope. After staining a sample with a fluorescent dye, it is irradiated with light of a specific wavelength. This causes the pathogens themselves to emit light.
Special filters are used in the microscope that allow only the light emitted by the sample to be seen. The pattern of this light can be used to detect the pathogen.
However, microscopic examination of the sample alone cannot yet determine the species or genus of the pathogen. This requires the establishment of a fungal culture.
For a fungal culture, material from the tissue sample is cultured onagar plates. These are nutrient-rich gel plates made from algae extracts.
For definitive pathogen detection, a clean culture free of foreign pathogens such as bacteria, yeast, or molds is necessary. Inhibitors are used for this purpose, and the laboratory environment should be sterile.
In some cases, dyes are also applied to the agar plates. These dyes indicate specific metabolic products of individual fungal species through coloration. Accordingly, they can also be used to identify the pathogen.
The samples must be incubated for two to three weeks at 28 to 30 degrees. Only in the case of so-called liquid cultures are approximately three days at 37 degrees usually sufficient for pathogen identification.
By then, the fungal cultures have developed enough to allow for pathogen identification under a microscope. The pathologist evaluates the appearance of the culture. Certain growth characteristics of the sample already narrow down the possible pathogens.
Fungal culture allows for the precise identification of the fungal pathogen © luchschenF | AdobeStock
The actual identification of the pathogen takes place under a microscope.
Once the sample culture has developed sufficiently after two to three weeks, the pathogen is identified under the microscope in addition to an assessment of its appearance.
To do this, a portion of the cultured dermatophyte is removed and placed on a microscope slide coated with a staining solution. Methylene blue is usually used to stain the sample.
The specific arrangement of the fungal hyphae, fruiting bodies, and spores then allows for species identification.
Another advantage of fungal culture is that it allows for the testing of treatment options. This makes it possible to assess the effectiveness of a medication without the patient having to take it yet.
Definitive identification of the pathogen through fungal culture can take several weeks.
In the case of a systemic mycosis, however, swift action is necessary to prevent the pathogen from spreading further. For this reason, treatment with antifungal medications often begins even before pathogen identification is complete.
Broad-spectrum antifungals are usually used in such cases. These target not just one pathogen, but several at once. Nevertheless, the treatment may not be effective because it does not target the specific pathogen.
Early fungal diagnosis and the initiation of a fungal culture are therefore of great importance.
Every physician listed in the Leading Medicine Guide has attained the highest level of training and certification within their respective medical specialty society. Furthermore, we contacted this physician based, among other factors, on their case volume (surgeries, treatments, and therapies), which we determined by cross-referencing various publicly available sources. Following discussions with the selected physicians and the directors of the medical facilities, as well as a subsequent internal review, they were admitted to the Leading Medicine Guide.
The quality assurance of the Leading Medicine Guide is further ensured by 8 admission criteria. Each member must meet at least 6 of them:
