Mycoses

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Pathogens are organisms that have the ability to cause disease in man. These organisms are often microscopic and can only be seen under the microscope.

Virulence is a metric used to measure the disease causing ability of a microbe. The the degree of pathogenicity is known as Virulence.

Mycology is the study of fungi of medical importance.

There are lots of organism that are classified as fungi, however mycoses is a study restricted to the disease causing fungi.

Fungi in general are non motile. They can not move from one place to another, without the aud of an external agent like wind, water or man.

There are two types of fungi

First, Unicellular fungi e.g Yeast

Then Multicellular Fungi e.g Mould

The commonest form of fungi in the immediate environment is mushrooms. Some of this is edible and is used by many to prepare different kinds of food, like soup.

Although this organism is edible, not all are. Poisonous mushrooms do exist. Care should be taken to avoid their consumption.

Mycoses can be divided into 2 based of the site of primary infection

1.Onycomycosis: (fungal infection of the nail )

2.Dermatomycosis: (infection of the skin)

Most of them (fungi), are Saprophytes. Saprophytes are organisms that live on decaying organic matter. Its activities such as feeding, excretion etc bring about the composition of this matter. Humans get infected when an individual gets wounded, by. a prick of stick or by any other sharp object in the soul. The direct contact between the broken skin and the soul containing this saprophytes, will initiate the infection.

Some of them are parasitic nature. As a parasite, they invade the body of their host organism, evade its immune system and get established in a niche where it lives at the detriment of the host. Some of the disease causing fungi falls under this category.

Fungal infection is serious but often overlooked medical condition that can kill. Poor enlightenment has left many in the dark. Self medication has also played a crucial role in this.

Tinea versicolor, a disease caused by malassezia fufur is the commonest form of fungal infection. Its clinical presentation is a lesion, characterised by brown patches in a mosaic form in the skin.

Those who have the disease don't experience any severe clinical symptom because it is a none inflammatory lesion.

The ones who visit the hospital do that for aesthetic reasons.

The types of mycoses includes;

Superficial Mycoses: this results when a fungus or group of fungi infect the outermost part of the skin (hair and nails).

The stratum corneum is the primary site of infection. Examples includes Tinea versicolor, Tinea nigra, black and white piedra.

Cutaneous mycoses:

fungal infection with lesions at the cutaneous area of the epidermis of the skin. Examples include: Microsporum spp. , Epidermiphyton spp. Trichophyton spp.

SubCutaneous Mycoses: this infection occurs at the deeper layer of the skin, the Dermis. Examples: Chromoblastomycoses, mycetoma, sporotrichosis.

Systemic Mycoses: when fungal elements break the skin barrier to infect the blood and the internal organs. Examples: Histoplasmosis, Blastomycosis.

opportunistic mycoses is suffered by immunocompromised patients, organisms like Candida Albicans, aspergillus and molds, cause serious and life-threatening systemic infection.

Dermatophycoses

Dermatophytes are keratinophylic fungi which invade and attack the keratin rich areas of the body. These areas include the hair skin and nail. Dermatophytes have an enzyme known as keratinase. This is responsible for the enzymatic digestion of the keratin rich epidermis, nail and hair.

A group of organisms that belong to 3 genera make up this class. They include

Genus Microsporon with example as Microsporon audvuini.

Genus Epidermophyton : e.g E. floccossum.

Genus Trichophyton: e.g T. rubrum.

Infections caused by dermatophytes are generally referred to as Cutaneous Mycoses. This disease are named after the regions of the body they infect.

Tinea coporis – body

Tinea capitis – Scalp

Tinea barbae – beard

Tinea Cruris – groin

Tinea pedis – foot.

Tinea is a Greek word that stands for worm. This name was given to the disease because their lesions have a worm like appearance, in a ring form.

General Pathophysiology

The disease starts with the inoculation of the fungal element i.e the spores and hyphae, through an infected formite, or hair comb.

The rate of spread of the infection is accerlerated if a person gets infected in a family that shares personal belongings, this is seen in developing nations due to poor economic condition.

Zoophilic forms of the fungi can be transferred from pet animals like dogs as in Trichopyton canis, to humans through direct contact. These zoophilic species are naturally predominant in the soil from where they make contact with the animals.

However for an infection to be established adequate amount of the pathogen have to invade the broken skin of the victim. If the skin with other mechanisms of the inate immunity is intact, an infection will not be established.

There are predisposing factors that increase the risk of infection.

They include,

Diabetes mellitus

Poor hygiene

Peripheral circulatory disorders

Humidity between folds of skin in chubby individuals.

As a rule, arthropophylic fungi rarely cause an inflammatory lesion. They don’t stimulate the immune system so there is no allergic reaction associated with them. However dermatophycoses due to zoophilic fungal organism induce immune reactions and cause an inflammatory lesion.

Diagnosis

Sample collection:

Hair samples: infected hair is cut with tweezers into a kraft paper and transported to the laboratory.

Skin samples: Scrapings from the outer border of the skin at the ringlike lessions of the disease is collected into a sterile kraft paper. Sample from the borders are preferred to that from the center because the latter is often made up of dead organisms. These organisms die due to accumulation of waste and nutrient depreciation as a result of high completion.

Nails: nail is cut wit surgical blades into a clean kraft paper for examination.

Treatment with KOH follows. Depending on the thickness of the specimen, 10 -20% KOH/NaOH is used to digest the sample on a clean grease free slide under mild flaming.

Direct Microscopy follows. Fungal elements like arthrospores (macro-conidia) and hyphae that are greenish in color is looked out for, when spotted a preliminary diagnosis is made.

For further studies and specie differentiation, culture of the sample is carried out.

Specimen is buried into a sabouroud dextrose agar. In addition to the nutrients in this media, some other substances are added to inhibit the growth of saprophytic fungi (cyclo-hexamide). A broad spectrum antibiotic, chloramphenicol is also used to ensure the absence of unwanted bacterial growth on the media.

This will ensure that only the fungi of interest is allowed to grow on the media. it takes about 3weeks for fungal growth to occur.

Treatment is with antifungal drugs, like griseofulvin taken orally according to prescription. Clotrimazole can also be used against the disease. It is mixed with body lotions and cream then applied topically on the lesion.

Reference

https://mycology.adelaide.edu.au/mycoses/cutaneous/#:~:text=These%20are%20superficial%20fungal%20infections, Causative%20organisms

https://www.ncbi.nlm.nih.gov/books/NBK7902/#:~:text=There%20are%20three%20general%20types,fungi%20into%20the%20subcutaneous%20tissue.

https://courses.lumenlearning.com/microbiology/chapter/mycoses-of-the-skin/

https://www.infectiousdiseaseadvisor.com/home/decision-support-in-medicine/infectious-diseases/superficial-mycoses-dermatophytosis/
https://en.m.wikipedia.org/wiki/Mycosis

https://read.cash/@Infinikxs/mycoses-8c940735

https://read.cash/@Infinikxs/cutaneous-mycoses-6b01b848

https://www.uptrennd.com/post-detail/tinea-infection~ODQzMzk2