Eye, Fungi, Antifungals, Parasites (Week 5) Flashcards

Question

Viral causes of ocular infections

Answer 1

Adenovirus Coxsackie Herpes simplex Herpes zoster Varicella CMV RSV

Answer 2

Strep Staph Pseudomonas Neisseria Syphilis Borrelia (Lyme disease) Chlamydia (trachoma)

Answer 3

Mycobacteria (?) tuberculosis Leprosy Atypical forms

Answer 4

Mucormycosis Candida Others

Answer 5

Acanthamoeba Filariasis (elephantiasis) Toxoplasmosis Toxocara

Answer 6

1) **Direct** **contact** with or without disruption of normal protective barriers (contact lens, trauma, foreign bodies, birth canals, hands; ophthalmia neonatorum) 2) **Direct** **spread** (sinus infection spreading into orbit) 3) **Hematogenous** **spread** (retinal and choroidal infections, septic embolus from endocarditis, meningitis, fungemia; CMV retinitis) 4) **Iatrogenic** (post-lasik non-tuberculous mycobacterial infection)

Answer 7

Spread by **direct contact** Chemical conjunctivitis within 24 hours of birth **N. gonorrhoeae** within 4 days of birth **Chlamydia** within 3 weeks of birth **Herpes simplex**

Answer 8

Bacterial (H. influenzae, S. pneumoniae, M. catarrhalis (same as otitis media!)) Viral infection (**adenovirus**) Allergy

Answer 9

Good ophthalmic antibiotic Polymyxin: Gram - coverage Trimethoprim: Gram + coverage

Answer 10

1) Topical 2) Intravitreal injection 3) Systemic

Answer 11

Eukaryotes (have nuclear membrane, chromosomes, mitochondria) **Cell walls** made of complex polysaccharides (**chitin**, chitosan, glucans, mannans) **Plasma membrane** contains **ergosterol** (rather than cholesterol)

Answer 12

**Unicellular** fungi Reproduce by **budding** or **fission** Form colonies in culture (similar to bacteria)

Answer 13

**Multicellular** fungi Germ tubes grow with extension of **hyphae** (either septate or non-septate) Form cottony colony called mycelium

Answer 14

**Asexual** reproduction **without** **propagules** (hyphae form **new** **mycelium**) **Asexual** reproduction by **propagules** (either **conida** or **sporangia**)

Answer 15

In **environment**, grow as **mold** In infected **host**, grow as **yeast** This is **temperature dependent**

Answer 16

**Hypersensitivity** Mycotoxicoses (release **toxin**) **Colonization** **Invasive** disease (but virulence factors not as well understood)

Answer 17

**Allergic** reaction to fungal spores or other components Can cause **pneumonitis**, **rhinitis**, **asthma**, alveolitis, sinusitis Can do skin tests with purified antigens to diagnose

Answer 18

**Ergot** alkaloids: alpha-adrenergic agonist caused **vasoconstriction** and **gangrene**, and interaction with dopaminergic and serotinergic receptors caused hallucinations **Aflatoxins** (Aspergillus flavus) causes **liver** disease, and is possible **carcinogen** (contaminated peanuts) **Psychotropics** (psilocybin and psilocin used in rituals and as recreational drugs)

Answer 19

1) **Superficial**: outermost layer of skin and hair, colonization of mucosa 2) **Cutaneous**: extend into epidermis, invade hair and nail 3) **Subcutaneous**: invade dermis, subcutaneous tissue, muscle, fascia 4) **Systemic**: originate in lung, may disseminate to other organs

Answer 20

Colonize dead tissue from **dying skin cells** and **lipids** Usually **cosmetic** problems **Tinea versicolor** **(M. furfur**; pigmented macules, **"spaghetti and meatballs"** and likes fatty acid) **Tinea nigra** (**H. werneckii**; produces melanin) White or black piedra (Trichosporon species)

Answer 21

**"Dermatophytes"** = **Microsporum, Trichophyton, Epidermophyton** In epidermis Skin, hair, nails Clinical manifestation called **"tinea"** or **"ringworm"** Named for structure infected: **Tinea pedis, capitis, magnus, unguium, cororis, cruris**

Answer 22

Geophilic: reservoir in environment, soil Zoophilic: reservoir in animals Anthropophilic: like covered areas of skin All use **keratin** as nutritional substrate

Answer 23

Fungal infections invasive into **soft tissue** Sporotrichosis (**sporothrix shenkii**) is only one in US Usually at site of trauma May require surgery and antifungal therapy

Answer 24

**Sporothrix schneckii** Dimorphic Get from **rose thorn** scrape --\> tracks up **lymphatics** Causes **ulcerating lesions**, **nodules**, **adenitis and** rarely pulmonary and disseminated disease

Answer 25

**"Black molds"** **Chromoblastomycosis** **Phaeohyphomycosis** (chronic allergic sinusitis) Eumycotic mycetoma (madura foot)

Answer 26

**Dimorphic**: histoplasma, blastomyces, coccidioides (spherules), paracoccidioides **Monomorphic** yeast: cryptococcus Usually enter by **inhalation** in lung --\> **short** or **asymptomatic** **respiratory** infection --\> secondary spread or **dissemination**

Answer 27

Coccidioidomycosis = "San Joaquin Valley Fever" Inhaled from soil in **southwest US** **Mild respiratory** infection Some may get progressive **pulmonary infection** Dissemination to skin, bones, CNS (especially in dark skinned people) Erythema nodosum or erythema marginatum with associated non-infectious **arthritis** Unique yeast form (**spherule** with tiny coccidioides inside) **Thin walled cavity** Directly infectious to microbiologists because of environment **Complement fixation** (IgG to chitinase) correlates with active disease, use to monitor infection

Answer 28

**Candida** **Aspergillus** **Zygomyces** Fusarium Scedosporium Penicillium Pneumocystis

Answer 29

1) Fungal **cell wall** 2) Cell membrane (**ergosterol**) 3) **Nucleotide metabolism**

Answer 30

Echinocandins: **capsofungin**, anidulafungin, micafungin

Answer 31

Allyamine: **terbinafine** Azoles: ketoconazole, **fluconazole**, itraconazole, voriconazole, posaconazole Polyenes: **amphotericin B** (including lipid formulations)

Answer 32

Pyrimidine analogue: **5-flucytosine**

Answer 33

**Griseofulvin**

Answer 34

Polyene antifungal **"Atomic bomb"** of fungal infection Extremely broad spectrum; used for cryptococcus and aspergillus fumigatus Disrupt fungal cell membrane by binding directly to **ergosterol** and opening up a **channel** that lets **intracellular cations out** **IV** for systemic or **topical** for sinus Adverse effects: fast infusion can cause fever, chills, nausea; **nephrotoxicity** **Lipid formulations** show better tissue distribution and lower toxicity

Answer 35

Azole Not as well absorbed Not great spectrum of activity

Answer 36

Inhibit ergosterol synthesis by interfering with **lanosterol 14alpha demethylase** (fungal CYP450 molecule) Ex: **fluconazole**, voriconazole, posaconazole

Answer 37

Triazole IV or PO Active against **cryptococcus**, **candida** (best drug for candida), **coccidioimycosis** Gets into **CSF**

Answer 38

Triazole IV or PO Treatment of choice for **invasive aspergillosis** Active against candida Gets **into CSF**

Answer 39

Triazole PO Active against **zygomycosis, candida, aspergillus**

Answer 40

Allylamine Inhibits **squalene epoxidase** step to inhibit **ergosterol** synthesis Oral or topical Used for **onychomycosis, tinea** Adverse effects: GI upset, hematotoxocity

Answer 41

Inhibits **beta glucan synthetase** activity so cannot synthesize **cell wall** IV Ex: **caspofungin**, anidulafungin, micafungin

Answer 42

Echinocandin IV Use to treat **invasive candida**, **invasive aspergillosis** (second line or together with voriconazole)

Answer 43

Antimetabolite (prevents DNA and RNA synthesis) PO Used to treat **candida** and **cryptococcal meningitis** (together with amphotericin B)

Answer 44

Polyenes: amphotericin, **nystatin** Azoles: ketoconazole, butoconazole, **clotrimazole**, econazole, **miconazole** Allylamine: terbinafine, naftifine Antimetabolites: ciclopirox, tolnaftate, others

Answer 45

Treat **tinea corporis, cruris, pedis** with **topical** antifungal (clotrimazole, econazole; don't use products containing corticosteroids!) Treat **tinea capitis** with **systemic** therapy (terbinafine, itraconazole, griseofulvin, fluconazole) Treat **onychomycosis** (nail infections) with **systemic** therapy (terbinafine, itraconazole, griseofulvin, fluconazole)

Answer 46

**Fungal** infection of the **hair follicles** accompanied by **secondary bacterial** infection and marked by raised, usually pus-filled and spongy lesions

Answer 47

Free-living, eukaryotic cells (?) Parasite depends metabolically on host and causes harm to host Have mouth called cytostome Reproduce **sexually or asexually** Secrete protective coat and become **cyst** to infect humans; after ingestion can convert back into motile form called **trophozoite**

Answer 48

**Single celled** parasites **Amoebae**: entamoeba; have no distinct shape **Apicomplexa**: plasmodium, toxoplasma, cryptosporidium; have group of organelles at one end of cell **Flagellates**: giardia, leishmania, trypanosoma, trichomonas; have flagella

Answer 49

**Multicellular** parasites Nematodes: **round** worms Platyhelminths: **flat** worms (cestodes/**tapeworms**, trematodes/**flukes**)

Answer 50

1) **Direct contamination** (ingestion/fecal-oral, active penetration, passive transfer) 2) **Vector borne** (mosquitoes or other insects)

Answer 51

Microscopic observation of **stool sample** If do test **3x**, is 98% effective

Answer 52

Form the parasite is in when it infects humans (we **eat cysts**) To form cyst, the protozoa secrete protective coat and shrink into round armored form Non-dividing, rigid cell coat, resistant to water and dessication

Answer 53

Form the parasite is in when it **causes** **disease** (after we eat cyst, it gets into our **intestine** and converts back into **trophozoite**) Motile, **dividing** (binary fission), labile cell membrane

Answer 54

When trophozoites "hatch" from initial cyst

Answer 55

Have to do PCR assay because they look identical

Answer 56

Anthroponosis: only humans Zoonosis: humans and other animals (reservoir host is animal that maintains parasite in nature)

Answer 57

**Cyclosporiasis** AKA **Cyanobacteria-like Bodies** (CLBs) May cause **diarrhea** lasting up to **6 weeks** Occurs in **immunodeficient** adults and travelers Diagnosis with acid-fast stain (**acid-variable cysts** in feces) Fluoresce under **UV light**

Answer 58

Causes **Primary Amebic Meningoencephalitis** **Acute** infection in **normal** host Enters through **nasal passage** when in fresh warm water (**hot springs**, hot tubs) "Fowl" play! 95% of people **die** within 1 week of infection Exist as cysts, trophozoites, flagellates but **amebic/trophozoite** form is what infects us Diagnose by seeing amebic **trophozoites** in **CSF** and **tissue**, or **flagellates** in **tissue** Looks exactly **like bacterial meningitis** (high neutrophils, high protein, low glucose) but obvi n**o bacteria** when you culture Treatment: **amphotericin B**

Answer 59

Causes **Granulomatous** **Amebic Encephalitis** (GAE) by entering lower respiratory tract or broken skin **Chronic** infection in **immunocompromised** host Causes **Ocular Keratitis** (in normal hosts) if contaminates contact lenses!

Answer 60

Part of the **flagella** of protozoa

Answer 61

**Trypomastigote**: has **flagella**, is highly motile, is **extracellular** form of parasite **Amastigote**: no flagella, **intracellular** form of parasite

Answer 62

Does not affect humans, only infects **cows** Still carried by tsetse fly

Answer 63

Human HDL component **ApoL1** lyses T. b. brucei However, some people have **mutation** in ApoL1 that also causes **lysis** of **T. b. rhodesiense**, which sounds good but actually correlates with **greater incidence of kidney disease**

Answer 64

Only during the **acute phase** Not in the indeterminate and chronic phases (but do see **amastigotes in muscle**) This means that we can do microscopy to see flagellated protozoa in blood during the acute stage but must do **serology/PCR/xenodiagnosis** in the **indeterminate** and **chronic** phase

Answer 65

1) **Reduviid** **bug** **feces** (vector-borne) 2) **Congenital** (vertical transmission) 3) **Blood** transfusion 4) **Ingestion** (drink sugar cane juice)

Answer 66

**Old** world **cutaneous**: Africa, Middle East (L. **major**) = **oriental** sores **New** World **cutaneous**: Latin America (L. **mexicana**) = **Chiclera's** ulcer **New** World **mucocutaneous**: Latin America (L. braziliensis) **Visceral**: Africa, India, Brazil (L. donovani)

Answer 67

In Southern **Europe** Infects **children** and **HIV positive** people

Answer 68

1) **Promastigote** exits sand fly's mouth and goes into human bloodstream 2) Engulfed by **macrophage** 3) **Amastigotes** divide within **macrophage** 4) Amastigotes **released** and infect other cells

Answer 69

**Chills --\> fever --\> sweats** Parasites **invade RBCs** --\> RBCs **burst** they release lots of foreign material and the immune system responds to those antigens by creating **fever** (inflammation, cytokines, etc) --\> **hypothalamus** resets and causes profuse **sweating to stop fever**

Answer 70

1) **Sporozoite** comes out of mosquito and goes into human blood 2) Sporozoite gets to **liver** within 30 seconds 3) Sporozoite gets into **hepatocyte** and turns into **merozoite**, which replicates 4) Merozoites released into **bloodstream** and infect RBCs 5) In RBCs, merozoites replicate (by schizogony, NOT binary fission) then turn into **trophozoites** 6) Trophozoites turn into **schizonts** which undergo nuclear division but NOT cytoplasmic division so get **multinucleated RBC** 7) RBC **bursts** and **merozoites** **spread** to other RBCs (?)

Answer 71

**P. malariae** causes **immune complex disease** and **renal failure** Other Plasmodium species cause splenomegaly, hepatomegaly, immunosuppression

Answer 72

**P. vivax** causes **relapsing** disease due to reactivation of **hypnozoite** stage in **liver** **P. falciparum** causes **recrudescence** due to residual low levels of **merozoites** in **RBCs**

Answer 73

Only exists in **P. vivax** (and P. ovale) Some sporozoites don't divide in hepatocytes but form **dormant** hypnozoites in **liver** and can cause **relapse** of malaria months to years later

Answer 74

**P. vivax** binds **duffy** **antigen** receptor on immature RBCs and causes them to **enlarge** **P. falciparum** binds **several** **receptors** on immature and **mature** RBCs (which **can't enlarge**)

Answer 75

P. falciparum secretes protein that **inserts into RBC membrane** causing **"sticky knobs"** on outside of RBC that let RBCs **attach to capillary walls** Note: can undergo **antigenic** **variation** so host cannot mount successful immune response to clear parasite

Answer 76

**Primaquine** prevents relapse by **P. vivax** **Quinine** 100% effective but try not to use all the time because P. falciparum **resistance** is a problem **Chloroquine** only works in **some regions** because lots of resistance now (and toxicity) **Mefloquine** (LARIUM) causes GI and CNS disorders, **vivid dreams** **Atovaquone/proguanil (MALARONE)** is a mitochondrial and **DHFR inhibitor** used for **P. falciparum** **Pyrimethamine** (FANSIDAR) is a **DHFR inhibitor** **Artemisinin** (Qinghaosu) has been used in China for thousands of years but only **limited FDA approval in US**

Answer 77

Need to stimulate **cell-mediated immune system** and haven't been able to do that yet

Answer 78

Babesiosis (**Nantucket** Fever) Worldwide, but in NE and NW states of US Transmitted via **ixodes** deer **tick**, but mouse is reservoir host **Trophozoites** asexually bud and divide into **4 merozoites** that stick together to form an x-shaped tetrad ("**Maltese cross**") Treat with quinine and clindamycin

Answer 79

1st trimester: spontaneous **abortion**, stillbirth 2nd/3rd trimester: **chorioretinitis**, **hydrocephalus**

Answer 80

Rodent eats spore --\> **cyst** forms in **rodent** (intermediate host = asexual replication cycle) --\> cat eats rodent --\> **oocysts** form in **cat** (definitive host = sexual replication cycle) --\> cat poops out oocysts --\> oocysts form **spores**

Answer 81

1) **Ingest cyst (oocyst) in cat feces** from changing litter box 2) **Ingest tissue cyst (pseudocyst) in raw beef** 3) **Congenital** if mother gets **initial/active infection during pregnancy**

Answer 82

1) **Egg**: dormant, transmission (like cyst of protozoa) 2) **Larva**: immature, disease 3) **Adult**: mature, disease Note: 1 egg --\> 1 helminth

Answer 83

**Definitive** host: harbors **adult** stage **Intermediate** host: harbors **larval** stage Note: this is different from indeterminate host!

Answer 84

**Cutaneous larva migrans** (dog hookworm)

Answer 85

**Taenia solium, Taenia saginata**

Answer 86

**S. mansoni**: in adult **inferior mesenteric venules** and near rectum; eggs in **feces**; fibrosis around eggs trapped in liver and intestinal tract; **chronic Salmonella infection** **S. japonicum**: adult in **superior mesenteric venules**; eggs in **feces** **S. haematobium**: adult in **venules around urinary bladder**; eggs in **urine**; correlation with **bladder cancer**

Answer 87

**Whipworm** Similar to Pinworm (Enterobius vermicularis) but no perianal itching Bloody diarrhea, malnutrition, **anemia**, **rectal prolapse**

Answer 88

**Raccoon** roundworm Possible **bioterrorism** agent because eggs can be distributed in aerosol Visceral larva migrans can be asymptomatic but can cause blindness, neurologic damage, death No treatment

Answer 89

The **entire lifecycle** of the parasite occurs in the host without need for another host Usually eggs or larvae are ingested, grow into adults and then produce eggs or larvae that **must exit the host** (to incubate in soil, etc) in order to go infect a new host With autoinfection, **adult produces larvae that can penetrate intestinal wall (etc) and infect the host again right away without leaving!** Ex: **Strongyloides stercoralis**, Enteroius vermicularis, Taenia solium

Answer 90

**Amoebae**: entamoeba **Apicomplexa**: plasmodium, toxoplasma, cryptosporidium **Flagellates**: giardia, leishmania, trypanosoma, trichomonas

Answer 91

**Nematodes** (**roundworms**): Ascaris lumbricoides, Enterobias vermicularis, Trichinella spiralis, Strongyloides stercoralis, Necator americanus, Ancyclostoma duodenale, Onchocerca volvulus, Wuchereria bancrofti **Platyhelminths** (**flatworms**), Cestodes (**tapeworms**): Taenia saginata, Taenia solium, Echinococcus granulosus **Platyhelminths** (**flatworms**), Trematodes (**flukes**): Schistosoma

Answer 92

Due to fungal infection with **Mucor, Rhizopus** **Rhinocerebral** (sinuses, orbits, brain), pulmonary, cutaneous, GI, often fatal Diagnosis: **necrotic** **palate**, CT imaging of sinus, brain, non-septate hyphae at 45 degree angle (or 90??) Treatment: **surgical** **debridement**, amphotericin B synergy with rifampin, posaconazole

Answer 93

**Mold** with **banana shaped** macroconidia **Skin** disease, disseminated disease (**hematologic** malignancy, bone marrow transplant) Diagnose by blood culture in dissemination Use **voriconazole**, posaconazole (resistant to amphotericin B and caspofungin)

Answer 94

S apiospermum, S prolificans Local disease in immunocompetent hosts: **bone, joint, skin, eye** Immunocompromised hosts: **pulmonary infection, dissemination, brain** Culture from tissue Treat with **voriconazole**, itraconazole, caspofungin (may be resistant to amphotericin B)

Answer 95

P marnefeii **Dimorphic** found in SEA Immunocompromised hosts: disseminated infection with **skin** manifestation Culture from blood or tissue Treat with amphotericin B, itraconazole, voriconazole, terbinafine

Eye, Fungi, Antifungals, Parasites (Week 5) Flashcards

(119 cards)