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Rickettsia, Ehrlichia, Orientia, Anaplasma, and Coxiella are all
obligate intracellular parasites
Name 5 obligate intracellular parasites
Rickettsia, Ehrlichia, Orientia, Anaplasma, and Coxiella
What organism causes Lyme disease?
Borrelia burgdorferi (Gram-N spirochete)
What organism causes Rocky Mountain Spotted Fever?
What two organisms are transmitted by body lice, and thus have a solely human reservoir?
Borrelia recurrentis, R. prowazekki(epidemic typhus), R. quintana (trench fever)
What drug/class works very well on these diseases?
Name 3 spirochete disease agents
Borrelia causes Lyme disease which is characterized by
Not usually visible with conventional light microscopy
- Corkscrew motility
Most common tickborne illness in N. America and Europe
Lyme Disease, caused by Borrelia burgdorferi
Difficul to grow in vitro
- Few proteins in outer sheath, most of those are lipoproteins which are potent activators of innate immunity via TLRs
- Phase variation
When is lyme disease most commonly diagnosed? Which forms of tick are most commonly the transmitters of lyme disease?
Most commonly diagnosed in june/july (summer). Nymph and larva are most likely to cause disease because they are smaller and thus harder to feel on you. They must be on you 36-48 hours before you get lyme disease.
Characteristic expanding (bulls-eye) rash at site of tick bite in 60-80% of patients is called _____ and is diagnostic of?
Erythema migrans, Lyme disease
Early Localized Lyme Disease presents with?
Cure rate at this stage?
- Erythema migrans
- Flu-like symptoms- fever, headache, malaise, fatigue, myalgia, arthralgia, regional lymphadenopathy
99% cure rate at this stage
HOWEVER mostly misdiagnosed at this stage if there is no erythema migrans
Disseminated multiple erythema migrans is characteristic of what lyme disease stage?
Early Disseminated Lyme Disease
Can present with Bell's palsy and arthritis in large joints
Stages of Lyme Disease and characteristic symptoms:
- 1) Early Localized Lyme Disease: Erythema migrans at site of tick bite, flu-like symptoms
- 2) Early Disseminated Lyme Disease: Disseminated multiple erythema migrans, arthritis in large joints, Bell's palsy
- 3) Late Disseminated (Chronic) Lyme Disease: Chronic arthritis w/ pain and swelling, neurologicl disorders (numbness, tingling, shooting pains), cognitive defects (short-term memory loss), sleep disturbances, fatigue
In Late Disseminated Lyme Disease: Are spirochetes found in affected tissue? What is hypothesized? Why?
No spirochetes in affected tissue, autoimmune involvement is thought to be involved because it is associated with certain haplotypes.
What is the only stage of Lyme disease that does NOT respond well to antibiotics?
Late Disseminated (Chronic) Lyme Disease
Lyme Arthritis occurs in what stage of Lyme Disease? What joints does it primarily effect?
- Late Disseminated (Chronic) Lyme Disease
- Affects larger joints (knee or elbow), usually affects a SINGLE joint, bone/cartilage destructin are RARE
Lyme Disease Tx:
Erythema migrans/ facial palsies, mild cardiac disease
Doxycycline, amoxicillin, or cefuroxime axetil
Lyme Disease Tx:
Neurologic disease /cardiac disease/ arthritis
- Ceftriaxone IV
- (or doxycycline, amoxicillin, or cefuroxime axetil for up to 1 month)
Post-Tx Lyme Disease: (PTLDS)
Occurs in what percent of patients?
- 10% (last for months to years)
- Arthralgias, myalgias, cognitive defects, sleep disturbances, fatigue
- Possibly an autoimmune response
Relapsing Fever caused by
- Epidemic: Borrelia recurrentis
- Endeic: B. hermsii, B. turicatae
Relapsing Fever caused by Borrelia recurrentis (Epidemic) is transmitted by
Body lice (via skin abrasions by hemolymph of crushed lice)
More severe disease, only imported cases in USA
Relapsing Fever caused by B. hermsii and B. turicatae (Endemic ) transmitted by
- soft ticks
- 30 cases/yr in USA
Epidemic --> B. recurrentis --> Lice (single relapse)
Endemic --> B. hermsii, B. turicatae --> soft ticks (3-10 episodes)
Spirochetes in blood that undergo antigenic variation are seen in
Relapsing fever can cause
- Flu-like symptoms
- Hepatosplenomegaly, Jaundice
- Spontaneous abortion, premature birth
What stain do you use to stain spirochetes in Relapsing Fever?
Tx for Relapsing Fever
Doxycycline (tetracycline), Erythromycin (macrolide)- in pregnant women or children since can't use tetracycline
If Neurologic involvement: Ceftriaxone
Monitor patients being treated for Relapsing Fever for ____
Jarish-Herxheimer rxn (50%)
Jarish-Herxheimer reaction can be seen in patients being treated for
Rickettsia, Orientia, Coxiella, Ehrlichia, and Anaplasma:
Aerobic or anaerobic?
Of the obligate intracellular bacteria, which ones escape the endocytic vacuole? Where do they infect?
- They escape vacuole and ROVe the cell.
- 1) Rickettsia- endothelial cells of small blood vessels
- 2) Orientia- blood vessel epithelium, macrophages
- 3) Vasicuitis/rash for Rickettsia and Orientia
Of the obligate intracellular bacteria, which ones remain in the endocytic vacuole of the host cell (morulae)
- Coxiella and Ehrlichia- monocytes and macrophages
- Anaplasma- neutrophils
Two forms of Rickettsioses
Both are sensitive to _____
- 1) Spotted Fever Group
- 2) Typhus Group
Sensitive to doxycycline
Rickettsioses: Spotted Fever Group
Type of rash?
Rocky Mountain Spotted fever caused by?
- Centripetal (spreads from extremities to trunk)
- R. rickettsii
Which type of Rickettsia infection causes spotted fever with eschar?
4 Types of Recketssia in Spotted Fever Group
- R. rickettsii - Rocky Mountain Spotted Fever
- R. parkeri - Spotted fever w/ eschar
- R. akari - Rickettsialpox
- R. coronii - Mediterranean Spotted Fever (MSF)
2 Types of Reckettsia in Typhus group
- R. typhi (fleas)
- R. prowazekii (lice)
Types of Rash
Spotted Fever Rickettsias:
- SFR: Centripetal (extremities to trunk)
- TR: Centrifugal (trunk to extremities)
Classic triad of RMSF
- Rash (ankles/wrists --> palms, soles, trunk, face)
Rickettsialpox causative agent?
- Rickettsia akari (transmitted by mouse bite)
- Urban areas
- Eschar forms at bite site
- Treat with doxycycline, quinolones
Eschar + mousebite =
Ricketssialpox (Rickettsia akari)
Causative agent of Endemic or Murine Typhus (NOT typhoid)
Causesd by Rickettsia typhi
Transmission, causative agent.
Louse borne, R. prowazekki
Causative agent of Scrub Typhus
- Orientia tsutsugamushi
- Asia, Western Pacific
- Rash with eschars spreads from trunk to extremities, CNS complications
Human Monocytic Erlichiosis (HME): Morulae in cytoplasem of ______
Human Granulocytic Anaplasmosis (HGE): Morulae in cytoplasm of _____
Both are transmitted by hard ticks
Two cell types of Coxiella burnetti
- Small cell variant (SCV)- small like spore, can survive for months
- Large cell variant (LCV)- found in body, can survive at low pH's (allows phagolysosome fusion)
Q fever causative agent
Most common in
- Coxiella burnetti
- Most prevalent in active men, 25-40 year
Primary reservoir of Coxiella burnetti
Cattle, sheep, goats
30 year old male sheep/goat farmer probably has
Q fever (Coxiella burnetti)
Disease that's almost exclusively in patients with heart disease or valve defects--> subacute endocarditis
Chronic Q fever
Disease that can cause spontaneous abortion or premature labor in pregnant women.
Ab to Phase I and Phase II antigen (LPS)
Chronic Q fever
Category B-Bioterorrism Agen because it is highly infections an dcan be airborne