Fungal pathogens

What is the fungal cell wall made up from?

Glucan-chitin cell wall

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How do fungi reproduce?

asexually/ sexually/ spore formation

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What ribosomes do prokaryotes have?

Ribosomes smaller 16S + 23S

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What ribosomes do eukaryotes have?

Ribosomes large 18S + 25-28S

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What are the 3 types of fungal disease?

1) superficial 2) subcutaneous 3) systemic

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Name examples of superficial fungal infection (3)

1) dermatophytes 2)malassezia 3) candida

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Name examples of systemic fungal infection (2)

1) candida 2) aspergillus

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Where do dermatophytes cause disease?

Skin, hair, nail

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What are the 3 genera of dermatophytes?

1) trichophyton 2) microsporum 3) epidermophyton

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What is the site and disease of tinea pedis?

site= foot skin disease= athletes foot

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What is the site and disease of tinea unguium?

site= nail disease= fungal nail disease

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What is the site and disease of tinea cruris?

site=groin area skin disease= jock itch

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What is the site and disease of tinea corporis?

site= limbs and torso skin disease= ringworm

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What is the site and disease of tinea capitis?

site= scalp skin and hair disease= scalp ringworm

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What is the site and disease of tinea barbae?

site= face skin (shaved) beard and moustache

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Who is scalp ringworm usually found in?

prepubertal children

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Who is fungal nail disease usually found in?

adults

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Who is Athletes foot usually found in?

adults (not younger people) and sportsmen- more common in men than women

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What typically causes tinea pedis?

Trichophyton rubrum

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What are the clinical features of tinea pedis?

Uni- or bilateral, Itching, flaking, fissuring of skin Interdigital: toeweb skin wet and macerated Plantar: Soles of feet dry and scaly, if skin of whole of foot affected “Moccasin foot” Hyperhidrosis, secondary to infection may increase severity

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What is another name for tinea unguium?

Onychomycosis

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What are they typical causes of tinea unguium?

Trichophyton rubrum and T. interdigitale

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What are the clinical features of tinea unguium?

Thickening, discolouring, dystrophy, four main types i) Lateral/distal subungual Ii) Superficial white – usually in immunocompromised iii) Proximal iv) Total nail dystrophy

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What is the typical cause of tinea cruris?

T. rubrum

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What are the clinical features of tinea cruris?

Itching, scaling, erythematous plaques with distinct edges Satellite lesions sometimes present May extend to buttocks, back and lower abdomen

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What population is tinea capitis most commonly seen?

prepubescent children

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What are the clinical characteristics of tinea capitis?

Range from slight inflammation, scaly patches, with alopecia, “black dots”, “gray patchs” to severe inflammation Kerion celsi: boggy, inflamed lesions, usually from zoophilic dermatophytes Favus: presence of cup shaped crusts/ scrutula

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What is endothrix? which fungus is associated with this?

spores inside hair shaft (lead to black dots)--> tinea capitis

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What is extothrix? which fungus is associated with this?

spores outside hair shaft--> tinea capitis

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What is favic? which fungus is associated with this?

Hyphae only in hair shaft (favour)--> tinea capitis

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What are the clinical characteristics of tinea corporis?

Circular, single or multiple erythematous plaques May extend from e.g. scalp or groin Invasion of follicle “Majocci’s granuloma”

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What investigations would you do for dermatophyes?

microscopy and culture

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what treatment would you give dermatophytes?

Topical antifungal therapy: mild disease (self diagnosis and treatment) Terbinafine, clotrimazole Systemic antifungal therapy: severe disease

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What do you treat tinea wapitis with?

Systemic antifungals--> griseofulvin, terbinafine (topical with not be curative)

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Give examples of malassezia

M. sympodialis, M. restricta and M globosa

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Where are malassezia most frequent?

normal skin flora on head and trunk

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what diseases do malassezia cause?

Pityriasis versicolor, Role in seborrhoeic dermatitis and atopic eczema

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What are the clinical characteristics of pityriasis versicolor?

Hyper- or hypopigmented lesions Upper trunk Between puberty and middle age More common in tropics relapsing

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How would you diagnose pityriasis versicolor?

microscopy- Yeast cells and hyphal segments “Sphagetti and meatballs” Culture difficult and not interpretable

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How would you treat pityriasis versicolor?

Topical antifungals eg. clotrimazole, if fails oral fluconazole or itraconazole

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What diseases does candid cause?

superficial mucosal (oral and vaginal) disease “thrush”, also occasionally skin disease and keratitis, systemic disease

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List some candida species (4)

1)Candida albicans 2)Candida glabrata 3)Candida parapsilosis 4)Candida krusei

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Name superficial candida infections of the oral mucosa(4)

1) acute pseudo-membranous 2) chronic atrophic 3) chronic hypo plastic 4) angular cheilitis

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What are the clinical characteristics of acute pseudo-membranous infection?

1)low CD4 count (

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What are the clinical characteristics of chronic atrophic infection?

1) older patients 2) erythema

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What are the clinical characteristics of chronic hypoplastic infection?

1) oral leukaemia 2) lesions may undergo malignant transformation

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Who gets oral candidosis?

1)HIV/AIDS 2) antibiotic use 3) head and neck cancer 4) general debilitation in hospitalised patients

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Describe candida vulvovaginitis

affects women, during child bearing years, Pruritis, burning sensation, +/- discharge Inflammation of vaginal epithelium, may extend to labia majora

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How do you diagnose superficial candidiosis?

1)Clinical diagnosis and empiric therapy 2)Culture with identification and antifungal sensitivity testing where appropriate

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How do you treat superficial candidiosis?

Usually oral azoles, fluconazole highly effective resistance in normally sensitive species (e.g. Candida albicans) or naturally resistant species (Candida krusei) can be problem

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What anti-fungals should you not use in pregnant women and why?

Do NOT use oral fluconazole or other azoles in pregnant women, this increases risk of teratologies (e.g. heart defects), topical azoles eg clotrimazole

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What is the most common cause of systemic candidiosis?

candida albicans

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What are the clinical characteristics of candida osesophagitis?

Mainly in HIV Candida oesophagitis in 10-20% patients with oropharyngeal disease Pain/difficulty on eating/swallowing

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How id candida oesophagitis diagnosed?

endoscopy with biopsy

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What are the clinical characteristics of candida endocarditis?

Vegetations seen on heart valves Fever, weight loss, fatigue, heart murmur Difficult to treat without valve replacement

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What is candida endocarditis a consequence of?

candidaemia

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Who gets candida endocarditis?

IV drug users, valve surgery

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Who gets renal candidiosis?

immunocompromised premature neonates

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What are the clinical characteristics of renal candidiosis?

Fever, abdominal pain, oliguria, anuria

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Why id UTI from candida harm to manage?

few antifungals are secreted in urine

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Who suffers from UTI from candida?

women, diabetics, damaged/abnormal urinary tracts

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What is candida peritonitis a complication of?

peritoneal dialysis, perforation of bowel during surgery

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How would you diagnose candida peritonitis?

culture of Candida from peritoneal fluid

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How id candida peritonitis treated?

source control/drainage and antifungals

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What is hepatosplenic candidiosis?

disseminated form on candidosis

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What are the clinical characteristics of hepatosplenic candidosis?

During neutrophil recovery yeasts lodge in liver and spleen (rarely also kidney) Abcess formation (bulls eye sign), fever, liver function disturbance

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How is aspergillus spores spread?

inhalation- airborne spores

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Name aspegillus species

Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, Aspergillus terreus

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What does aspergillosis cause?

1) reaction to inhalation 2)aspergilloma 3) allergic bronchopulmonary aspergillosis 4) allergic sinus disease 5) chronic pulmonary aspergillosis 6) invasive pulmonary aspergillosis 7) invasive aspergillus sinusitis

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Who gets aspergilloma?

Patients with cavities from previous TB, sarcoid, surgery--> Form solid balls of fungus

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What can aspergillosis cause of they break up?

Haemoptysis

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What antibodies are present in allergic forms of aspergillosis?

IgE and IgG

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How would you treat allergic forms of aspergillosis?

steroids and/ or anti fungal

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What antibodies are present in chronic pulmonary aspergillosis?

IgG aspergillus

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How would you diagnose chronic pulmonary aspergillosis?

Consolidation, cavitation on chest CT Positive culture of Aspergillus from sputum and BAL

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What disease shows halo and air crescent signs on CT?

Invasive aspergillosis

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How would you diagnose aspergillosis?

Culture Serology antibody detection: immunocompetent antigen detection: immunocompromised (= neutropenic)

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How would you treat aspergillosis?

Aspergilloma, resection Allergic aspergillosis, steroids +/- antifungals CPA and invasive aspergillosis antifungals, itraconazole and voriconazole, amphotercin B

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Fungal pathogens

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