4/30 Fungal Infections and Immunizations Ch 18, 19, 20 Flashcards
GIve an example of herd immunity
Rates of disease in adults going down after most children were given vaccines.
Live vaccines can be transmitted from person to person - this is not usually a problem except in what circumstances?
Among immunologically vulnerable hosts
define passive immunization
How long does the protective effect last?
Giving a patient immunoglobulins from an already immune individual
Protectin lasts only a few weeks
define active immunization
stimulation longer-lasting immune responses via injection of something that stimulates an immune response in the host
examples of live attenuated vaccines?
is a single dose sufficient for immunity? explain
Examples: Polio, rotavirus, typhoid, BCG (for TB)
single dose may be sufficient; this type of vaccine can elicit broad immunity
example of inactivated vaccines; inactivated whole organisms?
-tetanus, diptheria, Hep B recombinant protein antigen, pneumococcal polysaccharide vaccine (PPV23)
example of vaccine given as viral-like particles?
HPV
Example of vaccines given as inactivated: bacterial capsular polysaccharide conjugated to an immunogenic protein?
comment on this type of vaccine?
- pneumococcal conjugate vaccine. H flu, meningococcal conjugate
- induce only B cell responses without conjugate; often require booster doses to be protective
what do we measure to determine if a vaccine has been “immunogenic”?
measure antibody responses.
define vaccine efficacy (what does it measure)?
how is it expressed?
Vaccine efficacy = measures the ability of the vaccine to prevent disease or disease-related events (death, hospitalization)
expressed as a percentage: # protected/#at risk
Determine efficacy via prospective randomized trial
adverse reactions to vaccines: generally mild or severe?
examples of reactions?
generally mild
can range from local injection site reactions to low grade temps
in immunocompromized pts, more severe systemic infection is possible
reports of febrile seizures, Guillian-Barre syndrome: hard to prove causality!
define universal vaccination
one approach to immunization; aim is to prevent all individuals from getting disease, commonly administered in childhood (unless there are reasons to give later in life)
example when would we vaccinate only risk groups rather than universally?
ex: giving Hep A immunization to travelers or others at particular risk
define underlying risk
can signify risk such as pneumococcal vaccination for immunocompromised and elderly hosts.
his notes don’t make much sense here.
for what diseases can we provide post-exposure prophylaxis?
rabies, measles, Hep B, HIV
for what disease do we only vaccinate after a disease outbreak?
menincococcus
2 contraindications to immunization with live vaccines?
- pregnancy
- immunodeficiency
most vaccination is voluntary or not?
are there any mandated immunizations?
most vaccination is voluntary
some are mandated by school requirements, military requirements, for healthcare workers
reason: unvaccinated people can be a risk to those around them.
Dimorphic fungi: what makes them dimorphic? why do we care?
organisms that live in the environment in one form, and in infected tissue in another.
In environment: filaments with hyphae and septae. In tissue: yeast form (round/oval structures that divide by budding)
The diseases they cause (that we need to know about) are called Deep Mycoses - meaning that they are not limited to skin or mucosa.
Histoplasmosis: geographic distribution?
what types of places will you find histo?
In US: misissippi/ohio river valleys
Global: Central/South america
Find it in caves, soils that have bird/bad droppings, chicken coops, renovating old houses
Remember the CF patient who went cave exploring? This must be why everyone was so horrified.
Patient visited a cave in Belize. has a fungal infection in his lungs. what is it? what med?
Histoplasmosis (based on cave, S america)
Itraconazole
Histoplasmosis: Pathogenesis?
Tiny little yeasts grow within macrophages.
causes reaction resembling TB - fibrosis, caseating necrosis
cytokines activated macrophages to kill yeasts.
Histoplasmosis: clinical sx?
initial: flu-like (cough, fever, malaise).
upon reinfection, may get acute pulm infiltrates; febrile illness
Chronic: fibrosis and cavitary infiltrates
all these fungi have what general presentation in immunocompromised?
cell-mediated reaction -> granulomas. the granulomas may disseminate and allow live fungi into other tissues
–> meningitis, bone granulomas, other organ lesions.
Kind of like TB that then spreads widely
How can we diagnose Histo?
Culture grown from resp specimen (or other sites, if dz is disseminated)
Histo: treatment?
- severe, progressive dz with CNS involvement?
- suppress chronic infection in immunocomp host?
Ampho B for severe/CNS disease
Itraconazole for immunocomp host
Blastomycosis: US distribution?
global distribution?
what types of places is it found?
US: Pretty widely spread from midwest -> east coast. His example was a guy from VT.
- Scattered worldwide
- Soil, rivers, ponds: ppl with outdoor occupations are at risk (ex: woodworker)
Blastomycosis: appearance of the yeast?
Broad based buds.
extracellular (not within Macrophages, as with Histo)
thick-walled yeast.
Blastomycosis: clinical sx?
Pulm infection
- Cutaneous - may resemble carcinoma!
- can disseminate to GU, CNS.
Blastomycosis: treatment?
Serious disease: Amphotericin B
Non-meningeal or moderate: Itraconazole
Blastomycosis: diagnosis?
Stains show yeast forms
Culture will reveal mycelial form
Sporotichosis: geographic presentation?
what types of places is it found?
Geog: worldwide
associated with rotting wood, moss, potting soil, rose bushes
Sporotrichosis: pathogenesis?
local inoculation (usually an arm/hand; think prick from rose bush)
- pyogramulamatous reponse
- lymphatic spread
Sporotrichosis: clinical sx?
local pustules/ulcers with PAINLESS red nodules forming along draining lymphatics (ascending lymphangitis.
may have osteoarticular involvement and tenosynovitis.
litlte systemic illness - lung involvement is rare.
Sporotrichosis: diagnosis?
culture: yeast colonies
cigar shaped yeast on histo but hard to find.
Sporotrichosis: treatment?
Potassium iodide: may assist macrophages in killing Sporo
Local heat
Itraconazole (?fewer side effects that Pot iodide)?
Coccidiomycosis: geography?
types of locations?
US: Western states, Arizona, Central valley of CA (–> valley fever)
-Central/S America
Found in soils, rodent burrows
Coccidio: pathogenesis?
inhaled spores, pulm infection
granulomatous response; may look like erythema nodosum.
Coccidio: sx?
Primarily pulm: remember valley fever + lungs
erythema nodosum
may disseminate to bone, skin, meninges
Coccidio and immunocompromised pts: sx?
HIV+ at incr risk
may disseminate in these patients.
Coccidio: dx?
serology for antibodies
culture (but watch out; aerosolizes rapidly!)
Coccodio: tx?
Mild/primary dz usually not treated (but FA says itracolazole)
Ampho B for progressive dz/HIV patients
Candida: what are the normal host defenses?
- Phagocytic. Monocytes, macrophages, eosinophils can all ingest candida
- Cellular immunity. as evidenced by HIV patients (impaired cellular immunity) being at incr risk for Candida
Candida: clinical manifestations?
Mucus membranes!
-Vaginosis: thick creamy discharge. itching. erythema
Esophagitis: Pain w swallowing, feeling of obstruction.
Thrush: can be scraped off. white patches on tonge etc.
Candidemia: what is this?
what are sx?
risk factors?
dx?
Invasive candida that has reached the bloodstream
sx: spectrum: mild fever to sepsis.
Risk: immunocompromised, central IV catheters
Dx: blood culture
Candidemia: what drugs to give?
Ampho B, Caspofungin, or Fluconazole (PO)
may need to remove foreign bodies (catheter, IV)
Aspergillus: what are the host defenses?
sim to candida
- Phagocytic cells
- Cell mediated immunity
Classic presentation of Aspergillus?
- cavitary lung lesion “fungus ball”
- May colonize sinuses
- May dessimate, esp in immunocompromised
Aspergillosis: Treatment?
- for sinus disease, focal necroticlesions?
- meds?
- for sinus disease, brain disease, fungal balls in lung: surgical debridement
- Meds: Voriconazole (Jullet’s pic with a V on it: 45’ hyphal angle)
Ampho B effective but toxic
Caspofungin for refractory
Posaconazole may work
Zygomycosis (aka mucormycosis): why is disease from this limited to immunocompromised people?
It is ubiquitous in the env’t; not very virulent
Mucormycosis: pathogenesis?
Enters body via resp tract. hyphae invade tissue with affinity to blood vessels.
Thrombosis/necrosis.
Mucormycosis: risk factors?
Diabetes, esp with acidosis
Mucormycosis: clinical sx?
Dx?
rhinocerebral mucormycosis. sinusitis, pain, ha, fever.
May eride through face and hard palate!!! -> cerebral abscess.
May need CT scan
Mucormycosis: Prognosis?
treatment?
very poor prognosis (25-80% mortality)
-Tx: surgery? Ampho B, Posaconazole (PO)
Cryptococcosis: Presentation?
CNS meningioencephalitis
cranial nerve involvement. headache, facial weakness, diplopia
Cryptococcus: diagnosis?
Cryptococcal Antigen testing. Mainstay of diagnosis.
Cryptococcus: Treatment?
- improve immune status
- serial lumbar puncture if needed (can cause incr CSF pressure)
- Fluconazole
- Ampho B and flucytosine (5-FU).
