Fungi as Human Pathogen Prepared by : Aws Abu Jaber Introduced to : Dr. Ghadeer Omar Advance Mycology An – Najah National University

* About 200-300 fungal species are known to cause human infection & ( warm blooded animal ) , fungal infection of human are most common in tropical region but now are increasing drastically in all region . * The use of antibacterial and immunosuppressive agent contributes to the increase in the number of fungal disease

fungal infection can be life threatening in these situation Even the fungi that do infect human and other warm blooded animal are ( for the most part ) opportunistic or cause only mild symptoms in normal this situation has changed with increasing use of immunosuppressant drug in AIDS and Cancer patient , burn victims and organ transplant patient fungal infection can be life threatening in these situation

Mycoses Mycosis: Any fungal disease. Tend to be chronic because fungi grow slowly. Mode of infection: Inhalation Trauma Ingestion Rarely from person to person Most mycoses are not contagious

Clinical Manifestations of Mycoses : Fungal infections ( most common ) Toxicoses ( Poisoning ) Allergies ( hypersensitivity reaction )

Toxicosis Mycotoxicosis : caused by eating food contaminated with fungal toxin only . Mycetismus : poisoning caused by eating the fungus

Classification Of Mycoses : The clinical nomenclatures used for the mycoses are based on the : Site of the infection : Mycoses are classified as : superficial, cutaneous, subcutaneous, or systemic (deep) infections depending on the type and degree of tissue involvement and the host response to the pathogen.  

A- Superficial Mycoses : caused by fungi that invade only superficial keratinized tissue (skin, hair and nails) do not invade deeper tissues dermatophytes – most important Usually acquired by direct contact with the fungus and are the most common infections. Confined at the outer, dead layers of the skin, nails, or hair, all of which are composed of dead cells filled with a protein called keratin. Do not elicit immune response , Cosmetic problems , Limited to stratum corneum

Cont….. the following fungal infection and there etiological agent : Black piedra ( Piedraia hortae ) White piedra ( Trichosporon beigelii ) Pityriasis versicolor ( Malassezia furfur ) Tinea nigra ( phaeoannellomyces werneckii )

B – Cutaneous Mycoses : Cutaneous mycoses extend deeper into the epidermis , and also include invasive hair and nail disease . These diseases are restricted to the keratinized layer of the skin . Hair , and nails Unlike the superficial , host immune response may be evoked , resulting in pathologic changes expressed in the deeper layer of the skin .

Cont…. Cutaneous Mycoses may be classified as : dermatophytoses dermatomycoses.

1- Dermatophytoses : Dermatophytoses are caused by the agents of the genera : * Epidermatophyton * Microsporum * Trichophyton

General characteristics of Macroconidia and Microconidia of Dermatophytes Genus Macroconidia Microconidia Microsporum Numerous, thick walled,rough Rare Epidermophyton Numerous, smooth walled Absent Trichophyton Rare,thin walled, smooth Abundant

* Dermatophytes Characteristics : The dermatophytoses are characterized by an anatomic site-specificity according to genera. For example: Epidermophyton : floccosum infects only skin and nails, but does not infect hair shafts and follicles. Microsporum spp: infect hair and skin, but do not involve nails. Trichophyton spp : may infect hair, skin, and nails.

Dermatophyte characteristics : There ability to grow in the dead keratinized tissue where there metabolic product can induced an inflammatory response . the living tissue are not invaded because dermatophytes cannot grow at 37 C . There ability to produce keratinizes

2- Dermatomycoses : Dermatomycoses are cutaneous infections due to other fungi, the most common of which are Candida spp Dermatomycoses are any fungal infection of the skin or hair. A variety of yeast and molds can cause these infections and they are generally named after the location of the infection rather than the species that causes it

C- Subcutaneous Mycoses : Subcutaneous mycoses involve the dermis , subcutaneous tissue , muscle , and fascia . These infection are chronic and can be initiated by piercing trauma to the skin , which allows fungi to enter . these infection are difficult to treat and may require surgical intervention such as debridement .

Cont….. Fungal infections beneath the skin. Caused by saprophytic fungi that live in soil or on vegetation. Infection occurs by implantation of spores or mycelial fragments into a skin wound. Can spread to lymph vessels.

Cont…. There are three general types of subcutaneous mycoses: All appear to be caused by traumatic inoculation of the etiological fungi into the subcutaneous tissue: chromoblastomycosis mycetoma sporotrichosis Many of the fungi causing mycetoma are pigmented brown to black ( melanized fungi )

Systemic Mycoses Deep Mycoses Caused by D- Systemic Mycoses : Systemic Mycoses Deep Mycoses Caused by Primary Pathogens And Opportunistic Pathogen

Primary Pathogens (1) The primary pathogenic fungi are able to establish infection in a normal host Those fungal infection that spread throughout the body . The primary deep pathogens usually gain access to the host via the respiratory tract Result of infection by one of the four pathogenic , dimorphic fungi of the division Ascomycota .

The primary systemic fungal pathogens include : Coccidioides immitis Histoplasma capsulatum Blastomyces dermatitidis Paracoccidioides brasiliensis.

Blastomyces : is a primary pulmonary infection resulting from inhalation of conidia from the mycelial phase of Blastomyces dermatitidis . which convert in vivo to the parasitic yeast phase. Blastomyces dermatitidis - causes blastomycosis Dimorphic . Free living species distributed in soil . Symptom include fever, chills, cough, muscle aches, joint pain, and chest pain.( Similar to flu symptom ) Chronic cutaneous , bone , and nervous system complication

Coccidioides : Coccidioides immitis - causes coccidioidomycosis . Distinctive morphology - block like arthoconidia in the free living stage and spherules containing endospore in the lung . Lives in alkaline soils in semiarid , hot climate Arthrospores inhaled from dust , create spheruoles and nodules in the lung .

coccidioides immitis life cycle :

Histoplasma : Histoplasma capsulatum - most common true pathogen , causes histoplasmosis . Typically dimorphic Distributed world wide Grow in moist soil high in nitrogen content Inhaled conidia produce primary pulmonary infection that may progress to systemic involvement of a variety of organ and chronic lung disease .

Opportunistic Pathogens ( 2 ) Opportunistic pathogens require a compromised host in order to establish infection (e.g., cancer, organ transplantation, surgery, and AIDS) . Opportunistic mycoses do not typically affect healthy humans . On of the more significant causes of human dieseas and death and appeare only in immunocompromised individuals . Considered “classical “ opportunists because they are routinely encountered .

. Opportunistic fungi causing deep mycosis invade via the respiratory tract, alimentary tract, or intravascular devices. 5 genera of opportunistic fungi that cause systemic mycoses : Cryptococcus Candida spp Aspergillus spp Pneumocystis Mucor

Adaptation and Propagation Fungi often develop virulence mechanisms : ( e.g. , capsule and ability to grow at 37c ) and morphological form ( e.g. , yeast , hyphae , spherules ) that facilitate there multiplication within the host Enzyme such as keratinase . Dimorphism .

Mycoses are also among the most difficult disease to heal !!!! WHY ????

Fungi possess the biochemical ability to resist the oxidative damage produced by T cell during cell - mediated immune response Fungi are eukaryotic and thus biochemically similar to human cell , which mean most fungicide are toxic to human tissue .

Most fungi have ability to remove the toxicity by addition of hydroxyl group to the antibiotic , so that it can increase dissolve and remove the toxicity of antibiotic .

THANKS !! ANY Question ??