Opportunistic Mycoses Flashcards
Opportunistic mycosis
a fungal disease occurring in an animal/human with a compromised immune system
Opportunistic organisms
part of the body’s normal resident flora that become pathogenic only when host’s immune defenses are low
Reasons for altered immune system
- Immunosuppressive drug therapies
- Chronic diseases like diabetes mellitus
- steroid or antibacterial drug usage
Five types of opportunistic fungus
1) candidiasis
2) cryptococcosis
3) aspergillosis
4) mucormycosis
5) pneumocytosis
What is the “most important cause” of opportunistic fungal infection?
Candidiasis
Another name for Candida is…
yeast-like fungus
Candida is a normal flora to __, __, __, and ___. Colonization increases with __, __, and __.
- mouth, GI, vagina and skin in 20%
- age, pregnancy, hospitalization
Most common form of candida infection?
Candida albicans (75%). 5 other species have been isolated from humans.
Candida is unique because it grows as yeast at all temperatures, but at 37C it can form…
pseudohyphae and chlamydospores
There are 11 different kinds of candidiasis infection. Try to name 6.
1) Oropharyngeal
2) Cutaneuous
3) Onychomycosis
4/5) Vulvovaginal/balanitis (penile glands)
6) Oesophageal
7) GI
8) Bronchopulmonary
9) Peritonitis
10) Urinary tract
11) CANDIDEMIA/disseminated
Another name for oropharyngeal candidiasis:
Thrush
3 manifestations of oropharyngeal candidiasis
1) Pseudomembranous- white/grey scrapable plaque on hard palate and tongue
2) Erythematous/atrophic- on hard palate and tongue
3) Angular cheilitis- burning, sores at corners of the mouth with dry mouth, loss of taste, painful swallowing
* ** DD: oral HSV ***
2 manifestations of cutaneuous candidiasis
1) Intertriginous (very common)- moist, macular erythematous rash with typical satellite lesions present
2) Diaper candidiasis- erythematous lesions with erosions and satellite pustules. Begin in perianal area and spread toward genitalia
Risk factors for intertriginous candidiasis:
- areas of moisture and heat- axillae, groin, sub-mammary folds, intergluteal folds…
- especially with frequent friction, obesity, diabetes mellitus, and broad-spectrum abx.
Progression of candidal onychomycosis
Start as paronychia (whitlow = soft tissue around nail)
Difference between this and dermatophytic onychomycosis (starts under nail)
Predisposing factors for C. onychomycosis
-continuous wetting especially w/sugar solutions/flour
Symptoms of C. onychomycosis
- Painful, erythematous swelling around nail
- chronic cases can progress to onychoLYSIS- total detachment of cuticle from nail plate
Vulvovaginal candidiasis is common in women and associated with… (5 things)
1) Broad-spectrum abx
2) Low vaginal pH
3) Diabetes mellitus
4) Sexual activity
5) Oral contraception
Symptoms of vulvovaginal candidiasis
Intense vulvar pruritis–> itchy vag
Burning, erythematic
Dyspareunia = painful sex
… also a creamy white, curd-like discharge
Oesophageal candidiasis is associated with…
AIDS (an AIDS defining illness)
Severe immunosuppression following tx for leukemia or tumors
… can lead to septicemia and disseminated candidiasis
Symptoms of oesophageal candidiasis
Burning pain in the substernal area
Dysphagia
Nausea/vomiting
GI candidiasis
- from hematogenous spread
- patients with acute leukemia or other hematological malignancies might have stomach/gut ulcerations that allow for perforation –> peritonitis –> spread to liver, spleen, etc.
Causes of candidiasis peritonitis
Colonization of indwelling catheters for:
- peritoneal dialysis (CAPD)
- GI perforation due to ulcers, colitis, surgery ect.
Symptoms of candidiasis peritonitis
- Cloudy peritoneal dialysate containing greater than 100 leuko/mmcubed
- Fever, abdominal pain and tenderness
UTI candidiasis
Transient/asymptomatic candiduria during abx or corticosteroid use
Candida cystitis or bladder colonization can be caused by…3 ish things
1) prolonged catheterization while on abx
2) diabetes/glycosuria
3) previous bladder endoscopy or surgery
Candidemia
The presenece of yeasts in the blood with or without visceral involvement that can then disseminate to other organ systems –> endocarditis and hepatosplenic candidiasis
15% of hospital patient septicemias
Diagnosis by scrapings and microscopic observation:
Scrapes: skin, mucosal, vaginal
Culture blood and other body fluids
Observe purple yeast cells after gram stain
Candidiasis treatments
Topical: Nystatin and miconazole
Then, of course, itraconazole, fluconazole, Amph B
Two causes of cryptococcosis
Cryptococcus neoformans= var. neoformans (3 serotypes)
Cryptococcus bacillospora = var. gatti (serotype B and C)
General progression of cryptococcosis
Lungs –> resolve or brain (meningitis), skin, bones, organs
Cryptococcus structure is characterized by…
thick polysaccharide capsule; deposit melanin in cell wall when grown in catechols = presence of phenol oxidase
Pulmonary cryptococcosis can manifest as…
acute respiratory distress syndrome= fever, malaise, cough with very little sputum, pleurisy
CNS cryptococcosis
- Most diagnosed dissemination
- Meningitis and meningoencephalitis
- Death may occur 2 weeks to several years after onset, but is inevitable without treatment… also inevitable with treatment, but.. ya know.
- symptoms are typical increased intracranial pressure type things
Cutaneous cryptococcosis
- in 10-15% of cases
- present as just about every kind of lesion (papule, pustules, nodules, ulcers, draining sinuses) often with a block spot on top
Pathogenesis of cryptococcosis
Spores inhaled from eucalyptus tree (gatti) or bird poop (neo)–>survive neutral/alkaline pH and CO2 –>deposited in pulmonary alveoli/phagocytosed by alveolar MQ –>capsule is antiphagocytic/immunosuppressive and melanin protects from oxidative damage –> Host response: humoral and cellular –> Tissue destruction from “organisms burden” (no necrosis, inflammation, or fibrosis
Characteristic lesion of cryptococcosis
cystic cluster of yeast with no well-defined inflammatory response
Diagnosing cryptococcosis
Specimens in CSF, sputum, blood, urine
View with INDIA INK
Serology: capsular antigen; gram positive in 90% cases
Cultures in a few days
Treatment for cryptococcosis
Immune competent: fuconazole, itraconazole
Immune deficient: Amph B, flu cytosine
… avoid contact with birds
Most common organism for aspergillosis?
90% are aspergillus fumigatus
Describe aspergillus fumigatus, please.
Thin, septated hyphae, typically branch at 45 degree angles… sorta look like asparagus. Not so sure about the angle thing though.
What is the most common infection with aspergillus fumigatus?
Allergic Bronchopulmonary Aspergillosis (ABPA)
Tell me about ABPA.
Allergic bronchopulmonary aspergillosis is a Type I hypersensitivity response. Worse in people with asthma.
Symptoms: Wheezing, coughing up blood or characteristic mucous plugs, fever, malaise, cough
How do fungus balls form?
In pulmonary aspergillom, hyphae collect in pre-existing cavities (perhaps from TB) in the lungs. Results in cough, dyspnea, weight loss, and fatigue
What is a specific characteristic of invasive pulmonary aspergillosis? Name some other symptoms while you’re at it…
Characterized by invasion of blood vessels=angioinvasive with multifocal infiltrates
- Progresses fast and is fatal
- Fever, chills, headaches, cough, shortness of breath, chest pain, INVASIVE SINUSITIS–> necrosis
Invasive pulmonary aspergillosis can spread to other organs especially…
CNS (causing ring enhancement on MRI)
…also to skin, eyes, heart, kidneys, liver etc.
Where is aspergillus fumigatus commonly found?
Soil, insulating material, air conditioning and heating, and hospital air control
Two most common mycotic infection in bone marrow transplant recipients.
Candida and aspergillosis
Common genera of mucormycosis are (4). These are all __.
1) Rhizopus
2) Mucor
3) Rhizomucor
4) Absidia
= various zygomycetes
3 manifestations of mucormycosis
1) Rhinocerebral
2) Pulmonary
3) Cutaneous
Rhinocerebral mucormycosis originates in (body part).
The nose and sinuses (in poorly managed diabetics) and may progress to inflammation of cranial nerves
Rhinocerebral mucormycosis may cause blood clots that block vessels to the brain (thrombosis)
that’s all I have to say about that.
Symptoms of rhinocerebral mucor.
- acute sinusitis
- eye swelling/protrusion
- dark nasal scabbing
- fever
- redness of skin overlying sinuses
Pulmonary mucormycosis
Pneumonia that gets worse rapidly can spread to chest cavity, heart, brain
Cutaneous mucor.
a single, painful, hardened area of skin that may have a blackened center
Mucormycosis infection is limited to…
immunocompromised (diabetics and trauma)
Pathogenesis of mucormycosis
Spores inhaled–> germinate–>invade tissues/BLOOD VESSELS–> tissue necrosis
Involves: face, lungs, GI, skin
They really like dem blood vessels…
Diagnosing Mucormycosis
CT scan and MRI
Tissue specimen for definitive diagnosis
Treatment of Mucormycosis
SURGERY STAT
The most important fungal infection in the era of AIDS is/was:
Pneumocystosis. Aid for AIDS!
Organism causing pneumocystosis
pneumocystis (carinii) jiroveci pneumonia (PCP)
Symptoms of pneumocystosis
Typical pneumo things
- cough is often mild and DRY
- Rapid breathing
- chest x-ray lungs have “ground glass” appearance`
Diagnosis of pneumocystosis
Detect with: bronchoalveolar lavage, lung biopsy, sputum sample
Preferred stains: Giemsa, toludine blue, methenamine silver, calcofluor white
Treatment of pneumocystosis
Actue cases: STX; Cotrimoxazole (TMP-SMX)- Bactrim/Septra
-Pentamidine isothionate is also very effective (pentago ping-pong paddles)
Prophylaxis: Treat with STX and/or aerolized pentamidine (higher concentration in lungs)
**Note: STX is usually antiobacterial **
