Mycoses Flashcards
systemic mycoses - appearance
all dimorphic fungi
(EXCEPT COCCIDIOIDOMYCOSIS –> SPHERULE - NOT YEAST IN TISSUE)
cold (20c) –> mold
heat (37c) –> yeast
systemic mycoses -treatment . they can mimic
local infection: fluconazole or intraconazole
systemic infection: amphotericin B
they can mimic: TB (granouloma formation)
except, unlike TB, no peroson to person transmission
systemic mycosis - area (map)
- Histoplasmosis –> Mississippi and Ohio River valleys
- Blastomycosis –> Eastern US and Central America
- Coccidioidomycosis –> Southwestern US, California
- Paracoccidioidomycosis –> Latin America
systemic mycosis - size vs RBC
- Histoplasmosis - smaller
- Blastomycosis - same
- Coccidioidomycosis - much larger
- Paracoccidioidomycosis - much larger
Histoplasmosis - source / causes
Bird or bat dropping
- pneumonia and erythema nodosum
patient with suspected sarcoidosis deteriorates after steoroids
HIstoplasma
histoplasmosis - unique signs / symptoms / diagnosis
palatal/tongue ulcers / splenomegaly
- urine / serum antigen
Blastomycpsis - clinical features
lung: acute + chronic pnneumonia
2. skin: wartlike lesions, violacceous nodules, skin ulcers
3. Bone: osteomyelitis
4. GI: prostatis, epidiymo-orchitis
5. CNS: meningitis, epidural or brain abscess
GRANOULOMAS
Coccidioidomycosis causes / treatment
enedemic mycosis of southwest desert –> CAP often accompanied by arthralgias, erythema nodosum, erythema multiforme –> symptoms may last weeks to months –> no treatment for healty patients –> ketoconazole or fluconazole for patients with risk for dissemination (immunocompromised)
(VALLEY FEVER)
Coccidioidomycosis - case rate increases after … (WHY)
earthquakes (spores in dust thrown into air –> inhaled –> spheruls in lung
Coccidioidomycosis is also called
Valley fever
Paracocciddioidomycosis under the microscope
Budding yeast with “captain’s wheel formation
much larger than RBCs
systemic mycosis - erythema nodosum
- Coccidioidomycosis
2. Histoplasmosis
systemic mycosis - under the microscope
- Histoplasmosis –> Macrophages filled with Histoplasma
- Blastomycosis –> Broad-base budding
- Coccidioidomycosis –> spherule filled with endospores
- Paracoccidioidomycosis –> captain wheel
- -> shines
Cutaneous mycoses are divided to
- tinea (dermatophytoses)
2. tinea versicolor
Dermatohytes - appearance / include …
branching septate hyphae visible on KOH preparation with blue fungal stain
- Microsporum
- Trichophyton
- Epidermophyton
Cutaneous mycoses - types
- tinea capitis (dermatophytoses)
- tinea corporis (dermatophytoses)
- tinea cruris (dermatophytoses)
- tinea pedis (dermatophytoses)
- tinea unguium (dermatophytoses)
- Tinea versicolor
Tinea capitis occurs on (area of the body) / symptoms
- head scalp
- lympadenopathy
- alopecia
- scaling
- lympadenopathy
Tinea corporis - area of the body / symtpoms
torso (κορμός)
erythematous scaling rings (ringworm) and central clearing
Tinea corporis can be acquired from
contact with an infected cat or dog
Tinea cruris - occur in (area of the body) / symptoms
inguinal area
rash in the inguinal area without the central clearing seen in the tinea corporis
Tinea unguium - is also called / area of the body
onychomycosis
nails
Tinea pedis - how many varieties and which (MC) / AKA
- interdigital (MC)
- Moccasin distribution
- Vesicular type (blister)
AKA: athlete’s foot
Tinea versicolor is caused by
Malassezia spp (Pitirosporum spp)
Tinea versicolor - whether
any time of year but common in summer (hot, humid weather)
Tinea versicolor - under microscopy / treatment
spaghetti and meatballs
- topical and/oral antifungul medication
- selenium sulfate
- topical and/oral antifungul medication
opportunistic fungal infections - bugs?
- Candida ablicans
- Aspergillus Fugimatus
- Cryptococcus neoformans
- Mucor and Rhizopus spp.
- Pneumocystis jirovecii
- Sporothrix schenckii
Candida ablicans causes …. (and situations)
- Oral and esophageal thrush (immunocompromised –> neonates, steroids, diabetes, AIDS)
- vulvovaginitis (diabetes, antibiotics)
- diaper rash
- endocarditis (iv drug users)
- disseminated candidiasis
- chronic mucocutaneous candidiasis
- osteomyelitis (IV drugs)
Candida ablicans - morphology
DIMORPHIC
pseudohyphae and budding yeast at twenty c.
germ tubes at thirty seven c
Candida ablicans - treatment
topical azole for vagina
nystatin, fluconazole or caspofungin for oral/esophageal
fluconazole or amphotericin B for systemic
Aspergillus fugimatous causes … (and situations)
- invasive aspergillosis (immunocompromised and with chronic granulomatous disease)
- Allergic bronchopulmonary aspergillosis (associated with asthma, cystic fibrosis) –> bronhiectasia and eosinophilia
- Aspergillomas in lung cavitieus (esp after TB)
- produce aflatoxins –> hepatocellular CA
Aspergillus fugimatous - morphology
NOT dimorphic (only as a mold) Septate yphae that branches at 45 angle conidophore with radiating chains of spores
Cryptococcus neoformans causes / morphology
- meningitis
- cryptococcosis
- cryptococcal encephalitis
- heavily encapsuled yeast. NOT DIMORPHIC
5-10μm (NARROW BASED BUD)
Cryptococcus neoformans is found in
soil
pigeon dropping
Cryptococcus neoformans - lab
Culture on Sabouraud agar
Stain with india ink and mucocarmine
latex agglutination test detects polysaccharide capsular antigen
soap bubble lesion in brain image (in cryptococcal encephalitis)
Cryptococcus neoformans - lab - most specific test
latex agglutination test detects polysaccharide capsular antigen
Rhino-orbital-cerebral mucormycosis - manifestation
Acute/aggresive
fever, nasal congestion, purulent nasal discharge, headache, sinus pain
NECROTIC invasion of palate, orbit, brain
Mucormycosis - pathophysiology / diagnosis
fungi proliferation on blood vessel walls, pemetrate cribiform plate and enter brain
- sinus endoscopy with biopsy + culture
Rhino-orbital-cerebral mucormycosis - RF
- DM (ketoacidosis)
- hematologic malign
- Solid organ or stem cell transplant
Mucormycosis treatment
- surgical debridement
- liposomal amphotericin
- elimination of risk factors
Mucor morphology
NOT DIMORPHIC
irregular, broad nonseptae hyphae at wide angles
Pneumocystis jirevecii - morphology / originally classified as
yeast like fungus (disc shape)
originally classified as protozoan
Pneumocystis jirevecii - start prophylaxis when
CD4 cound drops under 200 cells/mm3 in HIV patients
sporothrichosis - manifestation
subacute / chronic
- skin papule –> ulceratio nwith nonpurulent odorless drainage
- proximal lesions along lymphatic chaein
- lymphadenopahrym deepr spread and sysemic symptoms are RARE
Sporothrix schenckii - morphology
Dimorphic, cigar shaped budding yeast that grows in branching hyphae with rosettes of conidia
Sporothrix schenckii - treatment
3-6 months of oral intraconazole
opportunistic fungal infections - dimorphic fungi
- Candida ablicans
2. Sporothrix schenckii
Oppostunistic fungal infection - morphology of every fungus
- Candida ablicans - dimorphic: pseudohyphae and budding yeast at 20c. germ tubes at 37c
- Aspergillus Fugimatus - not dimorphic (only as a mold). Septate hyphae that branches at 45 angle
conidophore with radiating chains of spores - Cryptococcus neoformans: heavily encapsuled yeast. not dimorphic, 5-10μm (NARROW BASED BUD)
- Mucor and Rhizopus spp: not dimorphic, irregular, broad nonseptae hyphae at wide angles
- Pneumocystis jirovecii: Disc-shaped yeast-like
- Sporothrix schenckii: Dimorphic, cigar shaped budding yeast that grows in branching hyphae with rosettes of conidia
Histoplasma in HIV - RFs and prophylaxis
RF: CD less than 150, endemic area: Ohio and Misisipi river valley (bird or bat dropping)
prophylaxis: intraconazole
progressive disseminated histoplasmosis - how to diagnose
urine or serum histoplasma antigen
also pancytopenia
- cultures takes 4-6 wks
progressive dissaminated histoplasmosis - treatment
amphotericin B for 1 week –> after clinical improvement –> oral intraconazole for 1 year
candida esoph - treatment
3-5 days fluconazole
special characteristics on manifestation of cryptococcal meningitis
no neck stiffness
no photophobia
increased intracranial pressure
Cryptococcal meingitis - treatment
IV amphotericin (+ fluticosine)
stop antiretroviral therapy for at least 2 weaks
maybe LPs to decreased pressure
PCP pneumonia treatment
TMP-SXM
prednisone if low O2 levels less than 92% or PO2 less than 70 or arterial - alveolar gradient more than 35
PCP - skin
nodular and papular cutaneous lesions of the external auditory meatus in immunocompromised patiends
indications for adding corticosteroids to TMP-SXM in PCP treatment
- Pa02 70 or lower
- A-a gradient 35 or more on room air
PCP alternatives
- Pentamidine (IV)
- atovquone
- Timethoprim + dapsone
- Clindamycin (IV or oral) + primaquine (oral)
PCP - workupe
- LDL elevated
- diffuse reticular infiltrates on imaging
- BAL
sporotrichosis - epidemiology
- sporothrix schenckii (dimorphic fungus)
- decaying plant matter / soil
- darnders + landscapers
Membrane pores formers - drugs - and mechasnim of action
- Amphotericin B 2. Nystatin
Binds to ergosterol (unique to fungi) –> membranes pores that allow leakage of electrolytes
(harmless for host cells)
Amphotericin B - clinical use
- SERIOUS SYSTEMIC MYCOTIC INFECTIONS : Histoplasmosis, Blastomycosis, Coccidioidomycosis, Mucor, Candida, Cryptococcus
- Naegleria Fowleri
- Leismania Donovani
Amphotericin B - meningitis
- with/without flucytosine for cryptococcal meningitis
- Intrathecally for fungal meningitis
Amphotericin B - administrate with (and why)
supplement K+ and Mg2+ because of altered renal tubule permeability
Amphotericin B - toxicity
- fever/chills (shake and bake)
- Hypotenesion
- nephrotoxicity
- arrhythmias
- anemia
- IV phlebitis
Amphotericin B - solution of toxicity
- Hydration decreases nephrotoxicity
2. Liposomal amphotericin –> decreased toxicity
Nystatin - clinical use
TOPICAL USE ONLY (TOO TOXIC FOR SYSTEMIC USE)
- oral candidiasis (swish and swallow)
- topical for diaper rash or vaginal candidiasis
Flucytosine - mechanism of action
Inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil by cytosine deaminase –> inhibits thymidylate synthetase
Flucytosine - clinical use
toxicity
Systemic fungal infections (esp meningitis caused by Cryptococcus) in combination with amphotericin B
- Bone marrow suppression
azoles - mechanism of action
inhibit fungal stero (ergosterol) synthesis by inhibiting the cytochrome P-450 enzyme that converts lanosterol to ergosterol (14-α-demethylase)
azoles - clinical use
Local and less serious systemic mycoses:
- Fluconazole: chronic suppression of cryptococcal meningitis in AIDS patients, all types of candidal infections, LOCAL systemic mycoses
- Intraconazole: (LOCAL systemic mycoses) Blastomyces, Coccidioides, Histoplasma
- Clotrimazole, miconazole: topical fungal infection
Azoles - toxicity
- testosterone synthesis inhibition –> gynecomastia (esp ketoconazole)
- liver dysfunction (inhibits P450)
Terbinafine - mechanism of action / clinical use
inhibits the fungal enzyme squalene epoxidase (Lanosterol synthesis inhibitor)
- Dermathophytes (esp onychomycoses)
Terbinafine - toxicity
- GI upset
- headaches
- hepatotoxicity
- Taste disturbance
Echinocandins - drugs and mechanism of action
Echinocandins –> 1. Anidulafungin 2. caspofungin
3. micafungin
inhibit cell wall synthesis by inhibiting synthesis of β-glucan
Echinocandins - clinical use
- invasive aspergilosis
2. Candida
Echinocandins - drugs and toxicity
Echinocandins –> 1. Anidulafungin 2. caspofungin
3. micafungin
GI upset, flushing (by histamine release)
Griseofulvin - clinical use
- oral treatment of superficial infections
2. inhibits growth of dermatophytes (tinea, ringworm)
Griseofulvin - toxicity
- teratogenic 2. carcinogenic 3. confusion 4. headaches 5. increased cytochrome P-450 and warfarin metabolism