02.12 Fungal Infections
- Common- Nail infections, ringworm, vaginal candidiasis, Oral candida
- Associated with travel to certain areas- Blastomyocosis, Valley Fever (Coccidioidomycosis), Cryptococcus gattii, Histoplasmosis, Paracoccidioidomycosis
- Associated with compromised immune systems- Aspergillosis, Candidiasis,
Fungal Diseases cannot be treated with antibiotics or antivirals- as they are designed to target bacteria and viruses respectively. In fact antibiotics can often lead to fungal infections.
- Antibiotics kill off both good and bad bacteria, often times destroying bacteria that compete with fungi and keep their numbers in check. Killing healthy bacteria often gives way for fungal cells to grow and take over causing disease.
- Fungal diseases can also be associated with travel as individuals are exposed to species that are not “native” to them and those funal cells can become invasive. Additionally individuals with compromised immune systems are more susceptible to fungal infections that a healthy immune system keeps in check
Mechanisms of action in treating fungal infections
- Binding to fungal cell membranes to compromise permeability ex. Polyenes
- Ployenes bind with steroids in fungal membranes forming channels that loss the fungal cell to loose its cytoplasm and contents.
- Inhibit the biosynthesis sterols, triglycerides and phospholipids in membranes of fungi. ex. imidazole/Azoles (treat a wide range of fungal infections)
- Breakdown of spindle fibers inhibits cell division ex. Griseofulvin (treats infection of skin, hear and nails).
- Drugs that bind with RNA and inhibit protein synthesis ex Flucytosine (treats serious fungal infections of blood, lungs, heat CNS, urinary system)
- Inhibit Cell Wall Synthesis ex. Caspofungin (treats aspergillus and candida infection)
- Binding to fungal cell membranes to compromise permeability ex. Polyenes
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Today we’re going to be talking about Fungal Infections.
“In this lesson on fungal infections we will cover some common examples of fungal diseases, we are also going to look a circumstances that increase the likelihood of having a fungal infection and lastly we are going to talk about the mechanisms of actions used in treating many fungal infections.
So some of the most common everyday diseases that are fungal are depicted here in the top row. Fungal nail infections or onychomycosis are a great example of a human fungal disease. Fungi love dark, moist environments and what better place than in a shoe!! This next photo is that of ringworm…and not it is not an actual worm but indeed a fungus amongus. Ringworm aka Dermatophytosis is a fungal infection of the skin. About 40 different fungi can cause ringworm. Risk factors include excessive sweating, obesity, exposure in wrestling or public showers to name a few. Another common type of a fungal disease is a vaginal yeast infection. These cause itching, burning and a white discharge. This infection can occur during pregnancy, uncontrolled diabetes, taking antibiotics or compromised immune systems. Some fungal infections tend to be travel related. Examples of these are like here in the first image in the second row, Blastomyocosis. This single celled fungus can infect the body through inhalation as well as through skin contact of soil, wood or leaves contaminated with it. It can cause flu like symptoms, including pneumonia as well as lesions on the skin and bone. , Valley Fever (Coccidioidomycosis), This fungus is known to live in the soil and causes flu like symptoms with a rash. Lastly we have Histoplasmosis which is a lung infection caused by breathing in these fungal spores often infected by soil with bird guano causing flu-like symptoms that usually go away on their own.
So often times fungal cells cause infection when given the opportunity. Otherwise the normal symbiotic bacteria that live on our skin or inside of us tend to keep these fungal infections at bay. However should a person need to take an antibiotic or use a steroid, this just might be enough of an opportunity that gives way to the reproduction of fungal cells in or on us that would not normal get a chance since either the bacteria have been destroyed by the antibiotic or our own immune system has been suppressed due to some situation like being on a steroid for a long period of time. Another opportunity that can be provided for fungal cells to infect is when they are exposed to individuals that are not used to their presence. So if you are travelling to a different location, you might get exposed to fungal cells that your immune systems nor your doctor are not entirely familiar with. You might genetically not be equipped to ward of this parasite and are now new territory for this fungus to take a hold of. A key clue to when a sick person may have a fungal infection is that he or she is being treated with medications for other types of infection but does not get better.
So now that we are familiar with some not so nice examples of fungal infections and opportunities for them to take hold, now let’s look at the mechanisms in which science has uncovered that will allow us to fight off these microscopic not so “fun-guys”. 😉 One method of compromise is to have a chemical that would Bind to fungal cell membranes. This binding can then result in any and all permeability of the fungus’s membex. Polyenes bind with steroids in fungal membranes that form little channels that cause the fungal cell to loose its cytoplasm and contents…..Which is inevitable death. A second approach can be to Inhibit the biosynthesis sterols, triglycerides and phospholipids which are all in the membranes of fungi. ex. imidazole/Azoles (treat a wide range of fungal infections)…these guys literally zap the production of cell membranes which without you are a goner.
Another discovered approach through the use of ex. Griseofulvin will breakdown of spindle fibers inhibits cell division (this treats infection of skin, hear and nails). Drugs that bind with fungal RNA ultimately inhibit protein synthesis…Flucytosine does just that to treat serious fungal infections of blood, lungs, heat CNS, urinary system. And lastly Inhibiting the Cell Wall from being Synthesized is like a castle with no mote. ex. Caspofungin used to treat aspergillus and candida infections.
So in summary, fungal infections can and do vary and some are much more common than others. Many infections take place due to an opportunity provided for those fungal cells to take hold, such as when someone is taking antibiotics and the wiping out of both good and bad bacteria gave way to fungal cells to flourish. Additionally traveling can expose individuals not inherently immune or predisposed to certain fungal infections in some cases by the activities taking place that brought them to the distant location (missionaries helping with farming or building exposed to dust/ soils, camping or outdoor activities expsoing to fungal cells unique to a certain part of the world. This compounded with the unawareness by those treating the individual (missing the diagnosis) can make proper treatments delayed or too late. And l lastly we looked at the mechanisms of drugs used to treat and cure fungal infections on a cellular level.
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