Micro U2 L2. Flashcards
Borrelia burgdorferi bacteriology
motile spirochete, flat wave shape, NOT spiral - larger (stain with silver, IF, standard microscopy), tick borne, mammal reservoirs, transmits in summer in 24-48 hrs
What is the pathogenesis of borrelia burgdorferi?
Lyme disease - 1. bite site to 2. blood to 3. heart, joints, CNS. NO toxins, primarily immune evasion
Signs/symptoms stage one of borrelia burgdorferi?
expanding macular rash (bullseye), some flu like symptoms (high fever if there is confection with erlichia or babesioa
Signs/symptoms stage two of borrelia burgdorferi?
months: cardiac and neurologic involvement: myocarditis, heart block, aseptic meningitis, bell’s palsy, bilateral facial nerve palsy
Signs/symptoms stage three of borrelia burgdorferi?
months: arthritis in large joints (knees) -> younger, chronic progressive CNS disease -> older
What are signs/symptoms of post treatment lyme?
lingering fatigue, joint pain, mental status changes
What labs can be done to confirm borrelia burgdorferi?
serology (ELISA) or IF (usually negative less than 2 weeks post infection) - will look the same if they’ve had lyme before. confirm with western blot or PCR
Treatment for stage 1 borrelia burgdorferi
doxycycline or amoxicillin
Treatment for late stage borrelia burgdorferi
ceftrixone
How do you know if treatment is working for borrelia burgdorferi/lyme?
jarisch herxheimer reaction
What is borrelia recurrentis and borrelia hermsii?
relapsing fever
Borrelia recurrentis and borrelia hermsii bacteriology
microscopically visible in blood smears, grow on special media
What is the vector/reservoir for b. recurrentis?
vector: body louse (from too much scratching) reservoir: humans
What is the vector/reservoir for b. hermsii?
vector: soft ticks; reservoir: small mammals, ticks
Which has a worse prognosis: b. recurrentis or b. hermsii?
b. recurrentis
What is a way to tell the difference between b. recurrentis and b. hermsii clincally?
b. hermsii has 3 relapses while b.recurrentis typically only has one
B. recurrentis and hermsii pathogenesis
spirochetes invade blood from bite site, multiply in many tissues -> general malaise and organ dysfunction -> neutralizing antibodies develop -> killing by immune system creates selective pressure for antigen variation -> disease resumes -> repeat
Diagnosis for B. recurrentis and hermsii
history of tick bite, fever (2+ episodes 3-5 days with well week inbetween), chills, headaches, organ dysfunction Labs: blood smear, culture optional
Treatment for B recurrentis and hermsii
tetracycline - Jarisch Herxheimer reaction
Rickettsia bacteriology
very short rods, hard to gram stain, arthropod vectors, obligate intracellular parasites, human is dead end host (infected by accident)
What are the similarities between Borrelia and Rickettsia?
- arthropod vectors 2. mammalian vectors 3. tetracycline sensitivity
What are the differences between Borrelia and Rickettsia?
- very short rods, hard to gram stain (borrelia large) 2. obligate intracellular parasites (borrelia not)
What are the three forms of Rickettsia?
- rocky mountain spotted fever 2. mediterranean spotted fever 3. typhus
Rocky mountain spotted fever
vectored by ticks, bacteremia (easily enter blood stream), invade and multiply in vascular endothelium, blood vessels leak as infected cells die causing a rash
What virulence factors do the spotted fevers have?
- omp A&B for adhesion 2. Type 4 secretion system for entry 3. phospholipase A2 to escape endosome 4. Act A - actin based cell-cell spread
Mediterranean spotted fever
dog ticks - not common in US - cause eschar type thing on skin
What is seen on exam of rocky mountain spotted fever?
headache, fever, myalgia, vasculitis rash (begins in extremities and then to trunk), history of tick, progresses to delirium, coma, DIC
Treatment of the spotted fevers
doxycycline if not pregnant (even for children). alternate for pregnant: chloramphenicol
Epidemic Typhus pathogenesis
bacteria multiply in vascular endothelium - untreated course ~2 weeks - mortality from vascular collapse or pneumonia
What is different about typhus compared to other vectored bacterial infections?
humans are normal host and reservoir* - vectored by lice which die from the bacteria!!!!
Brill-Zinsser Disease
recrudescent typhus - less severe than initial course, risk factors include malnutrition or inadequate antibiotics during first typhus
Murine Typhus pathogenesis
accidental transmission to humans of cat/rat typhus - seen in S and SW US
Scrub Typhus pathogensis
accidental transmission to humans of O. tsutsugamushi - vectored by chigger - milder than epidemic typhus
Diagnosis of typhus
epidemic: abrupt onset fever, chills, unremitting headache, lymphadenopathy, rash (TRUNK TO PERIPHERY), CNS symptoms, cough, deafness, flea bite, natural disaster, war, medical ro military personnel - more common in cold weather
How can you tell the difference between typhus and rocky mountain spotted fever by rash?
typhus: trunk to periphery while RMSF is peripher to trunk rash
Murine and Scrub difference from Epidemic clinically
more common in warm weather - cough and lymph node involvement more common - milder
Lab for ricketssia
IF assay, immunoassay, PCR
Treatment for ricketssia
antibiotics before labs come back - doxycycline or chloramphenicol (preg)
Ehrlichia bacteriology
tiny gram -; obligate intracellular; replicate in cytoplasm of WBC; form clusters called morulae(look like blackberries); accidental transmission to humans
Ehrlichia pathogenesis
asymptomatic - can have flulike symptoms, GI symptoms, meningitis, and/or DIC
Diagnosis for ehrlichia
severe headache, myalgias, fever, shaking chills, history of travel. LAB: CBC
Treatment for ehrlichia
doxycycline, alternate fluoroquinolones
Anaplasma bacteriology
small gram -; obligate intracellular; survive and multiply in early endosome of WBC (esp neutrophils); grow in morulae, vectored by ticks
Difference between anaplasma and ehrlichia
anaplasma: endosome of WBC instead of cytoplasm - more serious - can put healthy people in intensive care
Similarities of rickettsia, ehrlichia, anaplasma
small cocci-to-short rods transferred by arthropod vectors