Fungal Pathogens

Question 1

what type of cell wall do fungi have

Answer 1

glucan-chitin cell wall

Question 2

what can be used to identify types of fungus

Answer 2

reproduction technique, asexually, sexually or spore formation

Question 3

what are the 3 lifestyle of fungi

Answer 3

saprophytes - decaying organic matter
plant pathogens - more usually pathogenic in plants than humans
animal pathogens - small number compared to bacteria viruses and protozoa

Question 4

what 3 types of infection can be caused by fungal disease

Answer 4

superficial infection - affecting hair, skin, nails (eg dermatophytes, malassezia, candida)
subcutaneous infection - affecting subcutaneous tissue usually following traumatic implantation
systemic - affecting deep organs such as candida or aspergilus

Question 5

what are dermatophytes and what are the three genera

Answer 5

group of slow growing moulds seen as causes of disease in skin hair and nail
trichophyton, microsporum, epidermophyton
originate in soil, animals or confided to humans ie geophillic, zoophilic and anthrophillic

Question 6

give 5 examples of dermatophytes (tinea..)

Answer 6

tinea pedis - athlete's foot
tinea unguium - onychomycosis 
tinea cruis
tinea capitis
tinea corporis

Question 7

describe tinea pedis, appearance and causes

Answer 7

uni or bilateral
itching, flaking, fissuring of skin
interdigital (wet) and plantar (dry and scaly)
can infect toe nails or secondary infection
typically caused by trichophyton rubrum

Question 8

what is moccasin foot

Answer 8

athletes foot but affected the whole foot

Question 9

what is the appearance and causes of tinea unguium

Answer 9

thickening, discolouring, dystrophy
can be: lateral/distal subungual, superficial white, proximal, total nail dystrophy
caused by trichophytan rubrum and T. interdigitale

Question 10

what is the appearance and cause of tinea cruris

Answer 10

common to the groin -itching, scaling, erythematous plaques with distinct edges
more present in men and extends to buttocks, back and lower abdomen
caused by T. rubrum

Question 11

what is the appearance of tinea capitis

Answer 11

affects pre-pubescent children, inflammation, scaly alopecia, black dots and grey patches, inflamed lesions
can come from animals
invades the hair in humans - endothrix (spores inside hair shaft - black dots)
extothrix (spores outside hart shaft)
favic (hyphae only in hair shaft (favus)

Question 12

what is the appearance of tinea corporis and what are typical causes

Answer 12

circular, single or multiple erythematous plaques - extend from scape or groin
invasion of follicles (majocci granuloma)
causes - wide range of dermatophytes, anthropophillic or zoophilic

Question 13

how do you investigate and treat dermatophyte infection

Answer 13

microscopy and culture

Question 14

what is the treatment for dermatophyte infection

Answer 14

topical antifucgal therapy for mild disease = use terbinafine clotrimazole
for severe disease use systemic antifungal therapy

Question 15

in all cases of tinea capitis what do you treat it with

Answer 15

systemic antifungals = griseofulvin, terbinafine, itraconazole

Question 16

what is malassezia

Answer 16

genus of yeast such as m. sympodialis, m. restricta
part of normal skin flora from shortly after birth - mostly on head or trunk
caused by pityriasis versicolour
has a role in seborrhoec dermatitis and atopic eczema

Question 17

what is pityriasis versicolor, diagnosis and treatment

Answer 17

type of malassezia
hyper- or hypopigmented lesions
upper trunk - common in tropics and usually between puberty and middle age
use microscopy - yeast cells and hyphen segments (spaghetti and meatballs)
treatment - topical antifungals eg clotrimazole

Question 18

what is candida

Answer 18

large genus of yeast, often colonises the mucosal surfaces and GI tract in healthy people

Question 19

what causes thrush

Answer 19

superficial candidosis

Question 20

what is the appearance of oral candidiasis (oral thrush)

Answer 20

1) acute pseudo-membranous - low CD4 count lies than 200 cells per micro litre, more common in younger patients or asthma patients
2) older patients present erythema
3) angular cheilitis (inflammation of corners of the mouth)

chronic hypoplatsic
white sores in mouth

Question 21

what is the epidemiology of oral candidosis

Answer 21

HIV/Aids as T cell immunity important to prevent mucosal candidosis
antibiotic use - surpasses normal bacterial flora
head and neck cancer - radiotherapy affects salivary secretions

Question 22

what is the diagnosis of superficial candidiasis

Answer 22

clinical and empiric therapy

culture with identification and anti fungal sensitivity testing where appropriate

Question 23

what is the treatment of superficial candidiosis

Answer 23

oral azoles, flucanozole

Question 24

why would you not use flucanozole in pregnant women for oral thrush

Answer 24

increases risk of teratologies so use topical azoles such as clotrimazole for oral candidosis

Question 25

what is special about candida and which type is the most common

Answer 25

can infect any organ usually in compromised hosts

candida albicans still most common

Question 26

what is candidaemia and how do you treat it

Answer 26

candida in blood culture, 40 cases a year
treatment, remove lines, start anti fungal therapy
check heart and eyes

Question 27

what is candida oesophagitis and how it is diagnosed

Answer 27

mainly in HIV, in 10-20% patients with oropharyngeal disease
pain, difficulty swallowing
diagnosed by endoscopy with biopsy

Question 28

what is candida endocarditis cause by, appearance and treatment

Answer 28

rare consequence of candidaemia
can occur in IV drug users who have had valve surgery
vegetation seen on heart valves
fever, weight loss, fatigue, heart murmur
hard to treat without valve replacement

Question 29

describe renal candidosis

Answer 29

candida from blood lodges in kidney tissue during filtration
can occur in immunocompromised premature neonates
presents with fever abdominal, pain, oliguria and anuria

Question 30

describe urinary tract candida infection

Answer 30

ascending from genital tract or from catherisation
more common in women, diabetics or damaged urinary tract
can be hard to manage as few antifungals are secrete in urine

Question 31

describe the appearance of and treatment of candida peritonitis

Answer 31

complication of peritoneal dialysis or perforation of bowel during surgery
presents fever abdominal pain, nausea vomiting
diagnosis by culture of candida from peritoneal fluid
treatment by source control and antifungals

Question 32

what is hepatosplenic candidosis, presentation and treatment

Answer 32

disseminated form of candidosis
from candidaemia during neutrophil recovery yeast lodges in liver and spleen
abscesses form, fever, liver function disturbances
treatment - anti fungal but may be inappropriate as dead fungi triggers inflammatory response

Question 33

what is aspergillus fungi

give examples

Answer 33

genus of moulds - filamentous fungi
airborne spores - inhalation 
A. fumigates 
A. niger
A flavus 
A terreus

Question 34

what three types of infection can aspergillis carry out and what can it lead to in each situation

Answer 34

aspergillosis

1) allergic reaction - asthma, CF, allergic bronchopulmonary aspergillosis
2) chronic infection - chronic lung disease ie chronic pulmonary aspergillosis
3) invasive infection - immunocompromised (leukaemia) - invasive pulmonary aspergillosis

Question 35

describe the presentation and treatment of allergic aspergillosis

Answer 35

wheezing, breathlessness, loss of lung function, chest pain
airway inflammation - IgE and G reaction
responds to steroids and or anti fungal

Question 36

describe the presentation of chronic pulmonary aspergillosis and the clinical findings

Answer 36

chronic respiratory symptoms, cough, wheezing, chest pain
consolidation, cavitation on chest CT
positive culture of aspergillus from sputum and aspergillus IgG

Question 37

describe the presentation of invasive pulmonary aspergillosis

Answer 37

low neutrophil count
angioinvasion of lung tissue
halo and air crescent signs on CT
moderate to poor prognosis even with aggressive anti fungal therapy

Question 38

what can cause asperilloma, presentation and risk

Answer 38

patients with cavities from previous TB, sarcoid or surgery
form solid balls of fungus
often indolent but may break up and cause haemoptysis and are potentially fatal