Fungal Infections Flashcards
what are moulds
multicellular, filamentous fungi which produce hyphae
what are yeasts
unicellular, round or oval cells, reproduce by budding or fission
what are the common symptoms of tinea infections
itching, burning, pain, irritation
what are risk factors for tinea infections
environmental, clothing, hyperhidrosis, immunicompromised
what causes tinea infections
dermatophytes
moulds and keratinophilic
what are the three types of ringworm
tinea corpis = skin
tinea cruris = groin
tinea capitis = scalp
what are some treatments for ringworm
corporis and cruris = topical imidazole (clotrimazole, econazole or miconazole) also terbinifine >12s
oral therapy is terbinafine, itraconazole, griseofulvin (rural areas)
treatment for tinea capitis
oral treatment in addition to ketoconazole, selenium sulphide shampoos twice weekly
what is griseofulvin used to treat
microsporum spp
what is terbinafine used to treat
trichophyton
what are the features of griseofulvin
short half life
not retained well in keratin so longer therapy needed
narrow therapeutic range
avoid in liver disease/pregnancy/breastfeeding
what are the side effects of griseofulvin
GI, headache, cognitive, hepatobiliary, alcohol may potinate effects, interacts with oral contraceptives, take with or after fatty food to improve absorption
what is tinea pedis
athletes foot
what is chronic hyperkeratotic tinea
patchy fine dry scaling on the bottom of the feet
what are the symptoms of athletes foot
moist peeling, irritable skin between toes, clusters of blisters or pustules on the side of the feet or insteps, ringworm like tinea corpis
what people are prone to athletes foot
more exposed to the spores at home or during activities, their skin may produce less fatty acid, they wear occlusive footwear, they wear the same pair of shoes or socks for a long period of time, they sweat excessively, they have poor circulation in feet
what species’ can cause athletes foot
trichophyton rubrum
trichophyton mentagrophytes
epidermophyton floccosum
what is first line treatment for tinea fungal infection
imidazole cream 2-4wks
terbinafine cream 1wk (>12s)
combine with hydrocortisone if inflammed
what to use if topical antifungals are ineffective for tinea infection treatment
terbinafine 250mg od 2-6wks
itraconazole 100mg od for 30 days or 200mg bd 7days
griseofulvin 500-1000mg daily o divided dose 4-8wks
what is onychomycosis
fungal infection of the nails
what are the common infective species of onychomycosis
trichophyton rubrum
epidermophyton floccosum
trichophyton mentagrophytes
candida
what are the most effective therapies for onychomycosis
terbinafine and itraconazole
scrapings of the nail are needed
what is the most common subtype of onychomycosis
DLSO d=distal (top of nail) l=lateral (side of nail) s=subungal o= oncychomycosis
what is the systemic management of onchomycosis
1st line= terbinafine 250mg od
itraconazole 200mg bd for 7 days
what is pulse therapy
shorter, high dose
drug still remains in keratinised tissue but lower risk of side effects
what is the topical management of onychomycosis
mild disease or people who cannot take oral products
amorolfine (once or twice weekly for 6 months)
what does pityriasis versicolor look like
macules and/or patches of variable appearance (hyperpigmented), surrounded by normal skin
lesions worsen in tropical climates
affected areas include back, chest, abdomen, neck, upper limbs
face commonly affected in children
what is pityriasis versicolor
colonisation of stratum corneum, starts around puberty as the fungus feeds off fatty acids in sebum - it lives on the skin
how is pityriasis versicolor diagnosed
using a Wood’s lamp
yellow to yellow-green flouresence
what is the treatment for pityriasis versicolor
topical shampoos that will cover large areas
imidazole cream if small area
systemic itraconazole if topical insufficient
what causes superficial candida infections
candida albicans
c. glabrata
c. krusei
what topical therapies are used for oropharyngeal candida (oral thrush)
topical = imidazole like miconazole oral gel, polyene antifungals like nystatin oral= fluconazole
what is genital candidiasis
vaginal thrush
how does genital candidiasis present
intense vaginal and vulval pruritus, thick white discharge, pain on intercourse and urination
what treatment is used for genital candidiasis
imidazoles like clotrimazole
oral fluconazole or itraconazole
what is cutaneous candidiasis
folds of the skin, especially areas that chafe
what are the risk factors for cutaneous candidiasis
systemic antibiotics, HIV, skin conditions, skin maceration
what does disseminated mean
spread from initial localised source of infection
what is fungaemia
fungus detected in blood
what is severe sepsis
sepsis in addition to induced organ dysfunction/tissue hypo-perfusion
what is sceptic shock
sepsis induced hypotension persisting despite adequate fluid resuscitation
what happens during sepsis
circulatory system cannot handle supply demands of the body, inflammatory mediators compromise integrity of blood vessels, leaky blood vessels (intravascular fluid leaks out and reduces blood pressure)
reduction in blood pressure leads to hypoperfusion of organs
multi-organ failure and death
why are fungi more toxic
there is less specificity between fungal and mammalian cells as they are both eukaryotic
what are the types of fungal infection
invasive, disseminated, fungaemia, distant site infection
what indirect tests can confirm an invasive fungal infection
galactomannan antigen detected in sample
beta D glucan detected in serum
MC&S in sputum
what are the main causative organisms of invasive fungal infections
candida spp, aspergillus spp, cryptococcus spp, histoplasma capsulatum
what is apergillus
a mould that is common in the environment and can cause pulmonary infection (opportunistic)
blood cultures are difficult to obtain but antibody detection can be used
what is aspergillosis
invasive aspergillosis has lung origin
what is aspergilloma
a fungal ball growing in preexisting cavity
saprophytic
what are the complications of invasive pulmonary aspergillus
pneumonia, dissemination to CNS, local invasion to heart/vessels
surgery to remove locally invasive regions
what is the most common species of yeast
cryptococcus neoformans
cause pulmonary and invasive CNS infections
what is histoplasma capsulatum
environmental pathogen that causes pulmonary disease
what drugs are in the azole category
imidazoles (topical), triazoles (fluconazole, itraconazole, posaconazole, voriconazole)
what drugs are in the echinocandins category
caspofungin, anidulafungin
what drugs are in the polyenes category
amphoterocin
what is the triazoles mechanism of action
decreased ergosterol production throug inhibition of fungal cytochrome p450 enzymes, most are stativ
what are the side effects of triazoles
hepatic derangement, QT prolongation
what is the mechanism of action of amphoterocin
beinds to ergosterol in fungal cell membrance, creates pores, increasing permeability
cidal
broad spectrum but poor oral absorption so IV only
lipid formulation has reduced renal toxicity
what are the side effects of amphoterocin
renal toxicity, electrolyte disturbances, infusion reactions, cardiotoxicity, hepatotoxicity, blood dyscrasias
what are echinocandins
inhibit 1,3-beta-glucan synthase, prevent beta-glucan synthesis
what are some examples of echinocandins
capsofungin, anidulafungin, micafungin
what is flucytosine
nucleoside analogue, synergism with amphoterocin, need to do plasma levels, large problem with resistance
