Fungal Pathogens Flashcards
what type of cell wall do fungi have
glucan-chitin cell wall
what can be used to identify types of fungus
reproduction technique, asexually, sexually or spore formation
what are the 3 lifestyle of fungi
saprophytes - decaying organic matter
plant pathogens - more usually pathogenic in plants than humans
animal pathogens - small number compared to bacteria viruses and protozoa
what 3 types of infection can be caused by fungal disease
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
what are dermatophytes and what are the three genera
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
give 5 examples of dermatophytes (tinea..)
tinea pedis - athlete's foot tinea unguium - onychomycosis tinea cruis tinea capitis tinea corporis
describe tinea pedis, appearance and causes
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
what is moccasin foot
athletes foot but affected the whole foot
what is the appearance and causes of tinea unguium
thickening, discolouring, dystrophy
can be: lateral/distal subungual, superficial white, proximal, total nail dystrophy
caused by trichophytan rubrum and T. interdigitale
what is the appearance and cause of tinea cruris
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
what is the appearance of tinea capitis
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)
what is the appearance of tinea corporis and what are typical causes
circular, single or multiple erythematous plaques - extend from scape or groin
invasion of follicles (majocci granuloma)
causes - wide range of dermatophytes, anthropophillic or zoophilic
how do you investigate and treat dermatophyte infection
microscopy and culture
what is the treatment for dermatophyte infection
topical antifucgal therapy for mild disease = use terbinafine clotrimazole
for severe disease use systemic antifungal therapy
in all cases of tinea capitis what do you treat it with
systemic antifungals = griseofulvin, terbinafine, itraconazole
what is malassezia
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
what is pityriasis versicolor, diagnosis and treatment
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
what is candida
large genus of yeast, often colonises the mucosal surfaces and GI tract in healthy people
what causes thrush
superficial candidosis
what is the appearance of oral candidiasis (oral thrush)
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
what is the epidemiology of oral candidosis
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
what is the diagnosis of superficial candidiasis
clinical and empiric therapy
culture with identification and anti fungal sensitivity testing where appropriate
what is the treatment of superficial candidiosis
oral azoles, flucanozole
why would you not use flucanozole in pregnant women for oral thrush
increases risk of teratologies so use topical azoles such as clotrimazole for oral candidosis
what is special about candida and which type is the most common
can infect any organ usually in compromised hosts
candida albicans still most common
what is candidaemia and how do you treat it
candida in blood culture, 40 cases a year
treatment, remove lines, start anti fungal therapy
check heart and eyes
what is candida oesophagitis and how it is diagnosed
mainly in HIV, in 10-20% patients with oropharyngeal disease
pain, difficulty swallowing
diagnosed by endoscopy with biopsy
what is candida endocarditis cause by, appearance and treatment
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
describe renal candidosis
candida from blood lodges in kidney tissue during filtration
can occur in immunocompromised premature neonates
presents with fever abdominal, pain, oliguria and anuria
describe urinary tract candida infection
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
describe the appearance of and treatment of candida peritonitis
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
what is hepatosplenic candidosis, presentation and treatment
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
what is aspergillus fungi
give examples
genus of moulds - filamentous fungi airborne spores - inhalation A. fumigates A. niger A flavus A terreus
what three types of infection can aspergillis carry out and what can it lead to in each situation
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
describe the presentation and treatment of allergic aspergillosis
wheezing, breathlessness, loss of lung function, chest pain
airway inflammation - IgE and G reaction
responds to steroids and or anti fungal
describe the presentation of chronic pulmonary aspergillosis and the clinical findings
chronic respiratory symptoms, cough, wheezing, chest pain
consolidation, cavitation on chest CT
positive culture of aspergillus from sputum and aspergillus IgG
describe the presentation of invasive pulmonary aspergillosis
low neutrophil count
angioinvasion of lung tissue
halo and air crescent signs on CT
moderate to poor prognosis even with aggressive anti fungal therapy
what can cause asperilloma, presentation and risk
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
