Test 4/final Flashcards
Sporotrichosis
Sporothrix schenckii (subcutaneous)
Rose gardener’s disease
Cigar shaped yeast form
Lymphatic involvement
Chromoblastomycosis
Fonsecaea, Phialophora, Cladophialophora (subcutaneous)
Tissue morphology: Sclerotic/medlar bodies (yeast)
Verrucous califlower-like lesions on lower extremities (bare feet)
Phaeohypomycosis
Cladophialophora bantiana (brain lesions) = fatal (subcutaneous)
Usually forms a cyst on the hands
Tissue morphology: pigmented septate hyphal fragments
Eumycetoma
Draining sinuses containing granules
(subcutaneous)
Madura foot (bare feet)
*can also be caused by actinomycetes (bacteria)
Dermatophytes
Cutaneous
Digest keratin (nutrient source)
Tinea barbae, corporis, capitis, cruris (groin), pedis, manuum, unguinum (onchomycosis)
*favus variant tinea capitis = scutula that covers scalp (gross)
Pityriasis (tinea versicolor)
Superficial
Malasserzia furfur
Hyper/hypopigmented maculae usually on trunk/proximal limbs
Tinea nigra
superficial
Hortae Werneckii
Brownish maculae on palms and soles (looks like melanoma)
Black Piedra
Piedraia hortae (superficial)
Microscopic = discrete, hard, dark brown nodules on hair
White piedra
Trichosporan spp (superficial)
Microscopic = soft,white to yellowish nodules loosely attached to hair
Endemic, Dimorphic fungi
coccidioidomycosis histoplasmosis blastomycosis paracoccidioidomycosis penicilliosis marneffi
Coccidioidomycosis
Mnemonic: Coccidio Crowds san joaquin valley, “valley fever”
Coccidioides immitis (califiornia) Coccidioides posadasii (arizona)
Self-limited pulmonary febrile illness, lung lesions, valley fever (30%), highest incidence >65
*Microscopic = Spherule filled with endospores
Histoplasmosis
Mnemonic: Histo Hides within macrophages, bird and bat droppings
Histoplasma capsulatum
Found in soil, bat, and bird droppings
Asymptomatic (95%), pneumonia, chronic cavitary fibrosing mediastinitis, disseminate via RES, sepsis
- Microscopic = macrophage filled histoplasma
- Urine histoplasma antigen testing
African Histoplasmosis
larger, thick-walled yeast cells
pronounced giant cell formation in infected tissue
diminished pulmonary involvement
greater frequency of skin and bone lesions
Blastomycosis
Mnemonic: Blasto buds broadly
Blastomyces dermatitidis
Epidemiology: soil, near inland waterways
Asymptomatic (50%, more virulent), pulmonary infection, subcutaneous nodule, disseminate to bone or skin (immunocompromised)
*Microscopic = bud attached to parent by broad base
Paracoccidioidomycosis
Mnemonic: Paracoccidio Parasails with the captain’s wheel all the way to latin america
Paracoccideioides brasiliensis
Epidemiology: central-south america
Asymptomatic, nodular lesions in lungs, mucocutaneous orolabial and nasal lesions
*Microscopic = multiple budding yeasts the buds are attached to the parent cell by a narrow base “pilot’s wheel”
Penicillium Marneffei
Important cause of fungal infection in HIV people in southeast asia
with AIDS = dissemination to other organs, with hallmark skin lesions on face/trunk
*Microscopic = yeast form in ellipitcal with fission septae
Cryptococosis
Opportunistic yeast (heavily encapsulated) Found in soil and pigeon droppings Cryptococcus neoformans var grubii (N. american) C. gattii = pulmonary disease in immunocompetent
pulmonary can be asymptomatic or fulminant
CNS meningitis and cyptococcoma (leading cause of fungal meningitis)
- Microscopic = wide variation in size, india ink stain capsules appears as a “halo”
- capsular polysaccharide antigen detection in serum/CSF (very sensitive)
Candidiasis
Leading cause of opportunistic fungal infection
Candida albicans is the most common species
Diagnosis via microscope = budding yeast with pseudohyphae
Germ tube test
i. Localized disease of skin and nails (e.g. diaper rash)
ii. Mucosal infections (vaginitis, oral thrush, esophagitis)
iii. Invasive disease involving bloodstream, sterile sties, and/or multiple organ systems
USUALLY CATHETER RELATED, with risk of dissemination (must pull catheter)
2. 3rd most common cause of central line associated blood stream infection (CLABSI), 40% mortality rate
3. Also infect bone, joint, peritoneum, other deep organ system involvement
Hepatosplenic candidiasis
unique to cancer patients with prolong neutropenia, microabscesses in liver and spleen, blood culture usually negative
Diagnosis of Candida problems
Early diagnosis is difficult
i. Lack of inflammatory response in host
ii. Invasive diagnostic procedures risky (organisms do not hang out in blood, have to biopsy more invasive areas)
iii. Lack of sensitive, minimally invasive assays
Risk factors for invasive candidiasis
i. Antibiotic use (increase with each additional drug)
ii. Colonization with Candida
iii. Presence of central venous catheter
iv. Neutropenia (for hepatosplenic disease)
v. Staying in the hospital too long
Aspergillosis
Mnemonic: Acute Angles in Aspergillus
Most common cause of invasive mould infection
c. Aspergillus fumigatus = most common species
Unlike candida, aspergillus do not routinely colonize healthy persons
*Diagnosis via microscope = septate hyphae that branch at acute angles (<45 degrees), conidiophore with rare fruiting bodies
Aspergillosis Clinical syndromes
Clinical syndromes
Allergic bronchopulmonary aspergillosis
Aspergilloma in pre-existing cavity = secondary colonization of a lung cavity (fungus ball, hemoptysis, occasional local invasion)
Semi-invasive aspergillosis = chronic cavitary, chronic fibrosing, chronic invasive
Invasive aspergillosis
- Extremely serious, life threatening (60-95% mortality)
- Angioinvasive with tissue infarction, rapid spread, dissemination
- Risk factors = neutropenia, corticosteroids, transplant graft vs host disease
Galactomannan test
Test for aspergillosis
polysaccharide cell wall component, test approved for serial monitoring of hematologic malignancy patients
- Not useful if patient is on antifungal therapy
- Certain antibiotics have galactomannan (false positive) = Piperacillin-tazobactam
Zygomycosis
Rhizopus, Mucor, Rhizomucor, others
Usually cause rhinocerebral or pulmonary disease, can cause disseminated disease in immunocompromised
Diagnosis microscopic = nonseptate hyphae with sporangia, branch at wide angles
i. Difficult because any damage to nonseptate hyphae kills them (should be minced rather than crushed or ground)
Risk factors
Diabetes/diabetic ketoacidosis with hyperglycemia, acidosis hematologic malignancies, deferoxamine therapy, steroids, voriconazole prophylaxis in bone marrow transplant patients
Pneumocystis jiroveci (formerly P. carinii)
A major opportunistic myoctic infection (AIDS defining Illness), also seen in other immunocompromised patients
Diagnosis = cannot be grown on culture therefore microscopy is only option
i. Ground glass infiltrates
Interstitial pneumonia
- In AIDS patients, risk if CD4 <200
- Insidious onset on dyspnea, tachypnea, non-productive cough, and fever
- Ground glass infiltrates on CXR or cavitary lesions (looks like TB)
Treatment = trimethoprim-sulfamethoxazole (Bactrim) = antibiotic (not-antifungal)
i. Patients can worsen in first few days as large antigen load from lysing organisms is released from the lungs (give steroid to mitigate this effect)
Toxoplasmosis
Toxoplasma gondii
Oocysts = infectious form in cat stool
Tissue Cysts = infectious form in under cooked meat
Acute = asymptomatic
Acute in HIV = encephalitis, brain abscess
Congenital toxo = passed to fetus
2/3 = neurologic disease (chorioretinitis, intracranial calcification, hydrocephalus)
1/3 = generalized disease
Ocular taocoplasmosis = sequelae of congenital/acute infection (headlight in a fog)
Babesiosis
Acquire via tick bite (Ixodes sp.)
Easily confused with malaria (trophozoites, merozoites)
B. microti = northeast USA, recently in midwest and west coast (WA-1)
Disease = fever, hemolytic anemia Asplenia = increased risk of severe disease
Leishmaniasis
Promastigote = sand fly (Lutzomyia or Phlebotomus) Amastigote = intracellular macrophage
Reservoir = dogs, rats, humans (india)
Diseases
Visceral = RES infections = mostly fatal
Cutaneous = chronic ulcer with heaped-up margins
Mucocutaneous = ulcer and mutilating cartilage
Viscerotropic = spiking fevers, pancytopenia
American Trypanosomiasis
Typanosoma cruzi
vector = reduvid bug (kissing bug)
Acute Chaga’s disease = Chagoma, Romana’s sign (unilateral periorbital edema), fever
Chronic Chaga’s disease = cardiomegaly, megaesophagus, megacolon
African trypanosomiasis
Trypanosoma brucei = sleeping sickness
Vector = glossina sp (Tsetse fly)
Winterbottom’s sign
Sleeping sickness = brain perivascular cuffing
Amebiasis
Entamoeba histolyica, entamoeba dispar
Cyst = infectious, in water Trophozoite = invasive
Fecal oral spread, cyst is immediately infectious, person to person spread
Disease:
Acute rectocolitis (DYSENTERY)
Liver abscess
Diagnosis:
Colitis = stool exam for cysts/trophozoites
Liver abscess = serology
Giardiasis
Giardia lamblia, Resistant to chlorine!
Reservoirs = humans, beavers
Fecal oral spread (campers, day care, institutions for mentally retarded)
Disease = bloating gas, chronic or recurrent diarrhea
Malabsorption of fat (Mnemonic: Ghirardelli chocolates for fatty stools of Giardia)
Diagnosis = stool antigen test
Intestinal non-inflammatory protozoa
All worse in immunocompromised and cause diarrhea (non-inflammatory unlike amebiasis)
Giardia = immediately infectious, person to person spread, chlorine resistant, fatty stools
Cryptosporidiosis = immediately infectious, person to person spread, chlorine resistant, AFB stain
Cyclospora = not immediately infectious, no person to person spread, water/food (raspberries), AFB stain, Nepal (more infections)
Microsporidia = no immediately infectious, no person to person spread, extraintestinal infections (seen in AIDS pts), biopsy (stain poorly)
Intestinal Nematodes (roundworms)
Pinworm (intestinal) = mild infection; person-to-person spread within families, day cares
Trichuris trichiura (intestinal) = mild infection, but no person to person spread
Ascaris lumbricoides (intestinal with tissue migration) = largest intestinal nematode: lung phase (loeffler’s syndrome)
Hookworm (skin penetrating intestinal) = iron deficiency anemia
Stongyloides stercoralis (skin penetrating intestinal) = autoinfection results in long-term infection, hyperinfection during immunocompromise
Enterobius vermicularis
Pinworm (intestinal nematode)
life cycle = intestinal only
fecal oral spread
NOT a geohelminth = PERSON to PERSON spread!
human reservoir only (eggs immediately infectious)
Diagnosis = scotch tape test (eggs on perianal skin)
Clinical = Intestinal infection, anal pruritus complications = due to adult migration, UTIs
Trichuris trichiura
Whipworm (intestinal nematode)
life cycle = intestinal only
fecal oral spread
Unlike Enterobius it has an obligate period of soil development = no person to person spread
Diagnosis = stool sample
Clinical = usually asymptomatic, rectal prolapse
Ascaris lumbricoides
Giant roundworm (intestinal nematode) = largest one life cycle = intestinal with tissue migration oral acquisition, GI and tissue (lung) phases Eggs = resistant to harsh environment
Intestinal phase = abdominal pain, excreted worms
Pulmonary phase = Loeffler’s syndrome (eosinophilia, transient pulmonary infiltrates)
Diagnosis = stool, eosinophilia
Ancylostoma duodenale (old world) Necator americanus (new world)
Hookworm (intestinal nematode) = common cause of IRON-DEFICIENCY ANEMIA
life cycle = skin penetrating intestinal, must develop in soil
Acquired by walking barefoot
diagnosis = eggs in stool
Clinical:
skin = itch at site of penetration
Pulmonary (mild)
Intestinal = eat blood = iron deficiency anemia, protein loss
Strongyloides stercoralis
Life cycle = skin penetrating intestinal
Difference from hookworm = potential for autoinfection (does not need to develop in soil)
Can persist for years (>45 years) associated with HTLV-1
Diagnosis = larvae in stool (not egg)
Clinical:
skin rash
pulmonary = migratory (loeffler’s syndrome)
Chronic persistent infection = recurrent diarrhea
*Hyperinfection syndrome = in immunocompromised, overwhelming reproduction = allow gram negatives to penetrate blood stream = 86% mortality
Tissue Nematodes (Filarial Infections = vector-borne nematodes)
Adult worms = reside in blood or lymphatic vessels or in subcutaneous tissue, transmitted through an insect bite
Microfilariae = immature larvae in blood, skin, or eye
Wuchereria bancrofti = elephantiasis
Brugia malayi = elephantiasis
Onchocerca volvulus = river blindness
Loa loa = calabar swelling, eye worm
Lymphatic Dwelling Filariae
Wuchereria bancrofti
Brugia malayi
Wuchereria bancrofti
Lymphatic dwelling filariae
Life cycle = mosquito vector, adults resides in lymphatics, microfilariae in blood (diagnostic)
Nocturnal or diurnal periodicity of microfilariae in blood (correlates with mosquito feeding)
Clinical:
acute = adenolymphangitis (adult worms), filarial fever (microfilariae)
Chronic obstructive symptoms = elephantiasis of extremities (especially genitalia)
Brugia malayi
Lymphatic dwelling filariae
Clinical: Elephantiasis of the extremities (extremities more often, genitals less)
Tropical pulmonary eosinophilia
hypersensitivity reaction to microfilaria
hypereosinophilia associated with hypersensitivity to W. bancrofti, B. malayi
fever, weight loss, Loeffler’s like syndrome
Tissue Dwelling Filariae
Adult worm in tissue (vs lymphatics)
Loa Loa
Onchocerca volvulus
Loa loa
Tissue dwelling filariae
Adult forms in subcutaneous tissue, conjunctiva
vector = horsefly
Clinical
residents of endemic areas = asymptomatic
Calabar swellings = edema over bony prominence (lasts about a week)
Eye worm = few sequelae
Meningoencephalitis (microfilaria in CSF mostly due to treatment)
Onchocerca volvulus
Tissue dwelling filariae
River blindness (2nd most infectious cause)
Vector = black fly
*microfilariae in the skin
Clinical: subcutaneous nodules (bony prominences) dermatitis = due to microfilariae Regional lymphadenitis (hanging groin) Eye manifestations = blindness
*Diagnosis = skin snip
Nematode with larval stages causing human disease
Nematodes with worst pathology due to larval forms of parasites
Trichinella spiralis
Larva migrans (toxocara)
Anisakiasis
Trichinella spiralis
nematode (larval stage causes disease)
Life cycle = adult/larvae in human, larvae causes the disease
Acquired via eating undercooked pork/bear
Clinical: larvae disseminate via blood/lymphatics Encyst in muscles (nurse cell) = symptoms based on cyst load, splinter hemorrhages >1000 = life threatening *eosinophilia
Larval Migrans syndromes
nematode (larval stage causes disease)
Humans as aberrant hosts for dog and cat intestinal helminths
Toxocara canis = dog ascarid
Toxocara cati = cat ascarid
Acquire exposure to dog, cat feces in soil = larvae enter vasculature and travel to systemic circulation
visceral larva migrans (VLM) = liver, lungs, CNS, muscle = high eosinophilia, fever, hepatomegaly, etc
Ocular larva migrans (OLM) = eosinophilic inflammatory mass in eye
Cutaneous larva migrans = serpiginous creeping eruption
*eosinophilia
Anisakiasis
nematode (larval stage causes disease)
Found in various types of fish (sushi)
Humans are incidental hosts
Clinical:
stomach anisiakiasis = 1-7h after eating, epigastric pain, nausea, vomiting
Intestinal = 1-5 days, larvae invade ileal wall
Extra-intestinal = larvae may penetrate into peritoneum, pleural space
Trematodes (flukes) = flatworms
leaf shaped parasites 2 suckers (anterior, ventral) most are hermaphroditic (except schistosomes)
Schistosoma = blood flukes
Clonorchis sinensis = liver flukes
Fasciola buski = intestinal flukes
Paragonimus westermani = lung flukes
Life cycle: snail = first intermediate hosts (except schistosomes, 2nd intermediate host)
Trematode life cycle
humans pass eggs in feces –> miracidium develops in egg –> released into water –> miracidium enters SNAIL –> Cercaria leave sail (infectious!)
*Schistosomes = cercaria invade human skin –> become schistosomula –> then adult worms
Schistosomes
Trematode (flukes) = flatworms Life cycle: Cercariae penetrate skin (3-5 min proteases) Schistosomula migrates through blood Adult worm paired migration: S. mansoni = inferior mesenteric venules S. japonicum = superior mesenteric venules S. haematobium = bladder
Schistosomula and adult worms = Avoid immune response! via:
absorption of MHC Class I & II, DAF-like molecule (inhibits complement)
Eggs = elicit immune response = facilitate penetration of eggs through bowel, some do not penetrate = granuloma formation
Clinical:
Cercarial dermatitis = swimmer’s itch
acute schistosomiasis = katayama fever
Chronic schistosomiasis:
gastrointestinal = hepatosplenic, hepatomegaly, portal HTN, intestinal polyposis, colon cancer
Urinary = obstruction, squamous cell bladder cancer
Rare = CNS, lungs
Cestodes (tapeworms)
Flattened, no body cavity, all are parasitic hermaphrodites
Humans definitive hosts = harbor adult (sexual) worms, symptoms are minimal
Humans intermediate hosts = harbor larval stages, causes serious complications
Diphyllobothrium latum
Cestode (tapeworm), largest human tapeworm
Fresh water Fish tapeworm
Clinical:
often asymptomatic
*Vitamin B12 deficiency
Hymenolepis nana
Cestode (tapeworm), dwarf tapeworm
*eggs are immediately infections = human to human spread
autoinfection & hyperinfection (immunocompromised)
Clinical:
diarrhea
Taenia spp.
Cestode (tapeworm)
T. saginata (beef) = proglottids (15-20 uterine branches) are diagnostic, mild GI
T. solium (pork) = human can be intermediate host, larvae can disseminate throughout body/person to person spread, can cause cysticercosis (MOST COMMON HELMINTH IN CNS), can also cause calcifications, proglottids (7-13 uterine branches)
Echinococcus granulosus
Cestode (tapeworm)
Human = intermediate host
Dog = definitive host
Clinical:
Cystic hydatid disease
LIVER CYST, cyst rupture = sudden anaphylactic reaction
