Opportunistic mycoses Flashcards
The most virulent of the Candida spp is ___
Candida albicans
Name the virulence factors of Candida albicans
Surface receptors
Cell wall can act as an immunomodulator
Hydrolytic enzyme activity – acid protease, phospholipases
Host mimicry – production of a surface complement C3D receptor
Germ tube formation
**I see you on the surface, your walls try to modulate my immunity but I have hydrolytic enzymes and I can make you mimi-cry. Better get a germ tube and save yourself**
In addition to the other virulence factors, what is one feature of Candida albicans that allows it to adhere to and proliferate on the surfaces of plastic and prosthetic material?
Also forms a biofilm (releases dna into the environment then uses host response – fibrinogen etc to form biofilm)
*think - you’remaking a film from several candids*
T/F: The host response to invasive candidiasis involves acute and chronic inflammation as well as granula formation
Nah. Acute and chronic inflmammation yes but Candida is handled by neutrophilic infiltrate (no granuloma)
What happens with Candida infection in the case of neutropenia?
Neutropenia: the hyphae cut right thru tissue and exhibit extensive infiltration
The two clinical forms of candidiasis are __
Mucocutaneous
Invasive
What mucocutaneous candidiasis infection is an AIDS defining illness?
Mucocutaneous candidiasis: Oropharyngeal/esophageal candidiasis (HIV/AIDS defining illness)
What are the risk factors for gettig mucocutaneous candidiasis)
underlying diseases (HIV, diabetes)
corticosteroids,
pregnancy,
age,
antibacterial antibiotics
A common manifestation of Candidiasis in babies is ___
How can you tell that Candida is likely causing the infection?
Diaper dermatitis
Satellite pustules – indication of Candida infection in diaper dermatitis (keeping a dry diaper helps)
__ and __ of the esophagus is characteritic of esophageal candidiasis, seen in HIV patients
Cobble stoning effect and thickening of Candida bugs on non-keratinizing squamous epithelium
What is the Rx for esohageal candidiasis?
Fluconazole/Amphotericin B
How does neonatal oropharyngeal candidiasis develop?
Begins in the neonatal stage
Can be contracted from mom’s birth canal
*Angular kelitis (break down of corners of mouth)*
How do you Rx neonatal oropharyngeal candidiasis?
Rx: topical drugs (topical nystatin or clotrimazole)
___ is an inherited disorder of cellular immunity to Candida with concomitant polyendocrinopathies
Autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy (APECED): autosomal recessive inheritance
The most common manifestation of invasive candidiasis is ___
How woud you be able to Dx this?
Candidemia
Blood culture on Chrome agar **note that many pts actually have negative cultures**
What is one common manifestation of candidemia that can help you Dx it even if blood cultures are negative? (hint: its all about the eyes)
Candida endophthalmitis
**
Any pt with candidemia needs a dilated eye exam
Choroid is behind the blood vessels; bug adheres to choriocapillaris and causes chorioretinits (Rx systemically)
If not treated or Dx late, you’ll have permanent vision loss due to destruction of fovea
Name 4 other manifestations of invasive candidiasis
(hint: systems involved - heart, liver/spleen, kidney, brain)
Endocarditis (the tricuspid hills_
Hepatosplenic candidiasis (chronic disseminated candidiasis)
Renal candidiasis
Candida meningoencephalitis
Name 4 ways you can Dx candidiasis
Blood cultures
T2 Biosystem
Molecular marker: 1,3 Beta-D-glucan
Tissue biopsy
What is the treatment of mucocutaneous candidiasis?
Topical clotrimazole, miconazole or nystatin
Oral fluconazole (if advanced)
IV fluconazole or IV echinocandin in severe cases (if further advanced)
How do you Rx invasive candidiasis?
1st line Rx: echinocandins
Fluconazole (alternate and follow through)
AmB formulations (alternate) (severe and life threatening)
Which bug is this and what infection does it cause?
Aspergillus
Causes life threatening infection of the lung
The most common pathogenic species of Aspergillus include___
A. fumigatus
A. flavus
A. terreus
**fumigate your house and add a new flavor by getting a british terrier**
Which spp of Aspergillus is mainly seen in chronic, non-invasive infection?
A. niger
What are the virulence factors of Aspergillus spp?
Adherence receptors
Hydrolytic enzymes – collagenases, elastases, hemolysins, phospholipases
Complement inhibitor
Toxins
**I see you trying to adhere to me but see I can hydrolyze and inhibit all your toxic behavior**
Describe the pathogenesis of aspergillus (how we get infected and differences between immunocompetent/immunocompromised host)
Inhalation of canidia >> in normal host, fungi are phagocytosed and killed (not so much in immunocompromised host >> germination of fungi + hyphal invasion of lung >> angioinvasion)
The biggest risk factor for Aspergillosis infection is ___
a defect in neutrophil function (qualitative/quantitative)
Risk factors for Aspergillosis include:
chronic granulomatous disease (CGD)
transplantation
high dose corticosteroids
Liver cancer from aspergillosis is a toxin mediated disease, esp mediated by ___ (toxin name)
Aflatoxin***
Other manifestations of aspergillosis include ___ (affects CF pts) and chronic aspergillosis
Allergic Bronchopulmonary Aspergillosis (ABPA) and chronic aspergillosis (aspergilloma in TB patients)
Other infections include __(happens after trauma to the eye) and __(main aspergillus disease of the lungs)
keratitis
acute invasive aspergillosis
**
In invasive pulmonary aspergillosis, there’s angioinvasion and subsequent dissemination >> Nodules and halocytes around the nodules – classic aspergillosis
Which fungal infection causes the pathology below?
Invasive pumonary aspergillosis
In invasive pulmonary aspergillosis, there’s angioinvasion and subsequent dissemination >> Nodules and halocytes around the nodules – classic aspergillosis
On the left is a __ sign and on the right is a __ sign, both characteristic of pumonary aspergillosis
Halo sign
Crescent sign
(the curse of the crescent moon - beyonce getting aspergillosis)
How do you Dx Aspergillosis?
Galactomannan (serum and bronchoalveolar lavage fluid)**
Direct exam (calcofluor)
Culture
PCR
Biopsy
What is the bug below?
Aspergillus
**
After doing percutaneous aspirate: angular dichotomous branching septate hyphae, and angioinvasion
What is the 1st line Rx for aspergillosis?
the VI in Itra as a VIP
(voriconazole + isavuconazole)
Liposomal Amphotericin B (back up)
**2nd lines:
Posaconazole
Echinocandins (caspofungin)
Amphotericin B lipid complex
2 at risk populations for mucormycosis are ___(name the infections that affect those populations)
Diabetes mellitus with ketoacidosis - Rhinocerebral mucormycosis
neutropenia - Pulmonary +/- dissemination
How is rhinocerebral mucomycosis transmitted?
Inhalation of asex spores >> paranasal sinus infection >> tissue + blood vessel invasion >> invasion of orbit and eye >> extension to brain
People with (type of diabetes) are especially at risk for mucormycosis infection
Diabetes mellitus
**other risk factors are the same as for other diseases: neutropenia, having altered neutrophil function like transplantation or being on steroids; also iron overload**
What is the presentation of a diabetic pt with mucormycosis?
Diploplia (and maybe sinusitis - like that pt with the brain CAT scan)
Describe the characteristics of Mucormycetes
Characteristics: rapidly growing, nonseptate, aerial hyphae
What features would you on chest imaging for Mucormycosis infection?
Note that Mucormycetes infection also has pulmonary halo and angioinvasion (there’s also a reverse halo sign)
Which infection is this?
Ribbon like non septate hyphae branching at right angles
What is the Rx for Mucormycosis?
Amphotericin B + Isavuconazole
Adjunctive therapy:
Surgery
Restitution of innate host defenses
