Antifungals Flashcards
Name the fungi that causes common infection of skin hair and nails
Dermatophytes
Dermatophytes
- Health and immunocompromised are affected
- Dont colonise live tissues, instead keratinised areas e.g. nails and outer skin
- Use keratinases and elastase as virulence factors
What is the treatment against dermatophytes?
- Topical administration usually
- Oral medication - severe infections, when topical medications have not worked, adults only
- Terbafine/itraconazole
Name 3 fungi causing systemic fungal infections
- Cryptococcus neoformans (meningitis)
- Aspergillius fumigatus (aspergillosis of the lung)
- Pneumocystis jiroveci (pneumocystis pneumonia)
Which groups are affected by systemic fungal infections?
Immunocompromised
What is crypto coccus neoformans?
- Inhaled opportunistic pathogen
- Encapsulated yeast
- Contracted from he environment
What does cyrtococcus neoformans infection cause?
- Meningitis
- Cryptococcosis of the lungs
- Often both secondary infection with HIV
What is the treatment of crypto coccus neoformans infection?
- For meningitis: 2 weeks IV amphotericin B
* For non CNS infection: fluconazole or flucytosine
What are the reactions caused by aspergillus fumigatus?
- Allergic bronchopulmonary aspergillosis
- Invasive pulmonary aspergillosis
- Aspergilloma
What is allergic bronchopulmonary aspergillosis?
- Allergic reaction to fungal infection
* Associated with cystic fibrosis and asthma
What is invasive pulmonary aspergillosis?
- Becomes systemic and spreads throughout the body (via bloodstream)
- Common in immunocompromised
What is aspergilloma?
- An encapsulated fungal ball that develops in an area of past lung disease or lung scarring that has left the tissue vulnerable
- e.g. abscess or tuberculosis
What is the treatment of allergic bronchopulmonary aspergillosis
Prednisolone
What is the treatment of invasive pulmonary aspergillosis?
- Voriconazole
* Amphotericin B
What is the treatment of aspergilloma?
- No treatment unless bleeding occurs
* If bleeding occurs then surgery
What are the symptoms of pneumonia?
- Fever
- Cough
- Shortness of breath, rapid breathing
What is the treatment or prophylaxis of pneumocystis jiroveci?
Trimethoprim-sulfamethoxazole (anti-folate)
What is mucormycosis?
- Opportunisitc infection
- Environmental fungi found in soil, compost, animal dung
- Harmless in immune-competent
- Respiratory and sinus infections in immune-compromised
- seen in COVID patients
What are the azoles?
- Inhibitors of 14-methylsteol alpha-demethylase which produces ergosterol
- Fluconazole
- Miconazole
- Econazole
What is ergosterol?
An essential component of the fungal plasma membrane (it is the equivalent of the cholesterol)
Azasterols
delta 24- sterol methyltransferase inhibitor (not really specific enough)
What is the mechanism of action of terbafine?
Squalene 2,3- epoxidase inhibitor (also involved in the cholesterol pathway so bad effects)
What is the drawback of the azoles?
Cross resistance
What is amphotericin B?
- Binds to ergosterol
- It has a hydrophobic and a hydrophilic side
- Creates a pore in the fungal membrane
- Disrupts the plasma membrane potential and the cell dies
What is ambisone
- Amphotericin B is enclosed as part of the liposome
* Improves delivery and reduced toxicity
