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micro rickettsia, ehrlichia, coxiella, bartonella


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A. Rickettsiae are fastidious bacterial organisms that are
-obligate intracellular parasites
Properties of Rickettsiae
-difference BW ricketts and typhus and spotted fever
1. Pleomorphic, small, coccobacilli
2. Stain blue with Giemsa stain
3. Cell walls are similar to gram-negative bacteria
4. Rickettsiae grow in different parts of the cell; typhus group are usually found in the cytoplasm; spotted fever group in the nucleus
5. All rickettsia survive only briefly outside of a host
-Man is an
-The exception to this is
C. Almost all rickettsia pathogenic for man are maintained in nature in an arthropod-animal reservoir-arthropod cycle.
-accidental host in this cycle.
-epidemic typhus, which is maintained in a human- body louse cycle
Pathogenic Rickettsiae
1. Spotted Fever Group
a. Rocky Mountain Spotted Fever-Rickettsia rickettsii *
e. Rickettsialpox- Rickettsia akari'*
2. Typhus Group
a. Epidemic Typhus-Rickettsia prowazekii *
b. Murine Typhus - Rickettsia typhi *
E. Pathogenesis of Rickettsial Infection
Rickettsia enter the body through skin via the
bite of an infected arthropod vector. Once in the bloodstream the rickettsioses multiply in the endothelial cells of small blood vessels and produce vasculitis.
Most important rickettsial disease in North America
-Rickettsia rickettsii is a
-In the western U.S
-In the eastern U.S.
-In the southwest
Rocky Mountain Spotted Fever 1
a. parasite of ticks
1) . the wood tick (Dermacentor andersoni) is the vector
2) the dog tick (Dermacentor variabilis) is the vector
3) the Lone Star tick (Amblyomma americanum) is the vector
2) Risk factors:
1) 95% of cases occur April through September
dog exposure, residence in a wooded area
3. Clinical Manifestations
-Incubation period between tick bite and onset of symptoms
a. is 2-6 days
are the classic triad
b. Fever, headache and rash
Rash typically appears
-Rash begins ...spreads to
-Rash on the ______is typical
1) on the second or third day of illness
2) on wrists and ankles initially as macules, then petechiae; trunk
3) Rash on the palms and soles is typical
c. Other symptoms -

Complications include:
malaise, myalgias, vomiting, photophobia
-rash on outside usually means bad stuff on inside; Central nervous system abnormalities, respiratory failure, myocarditis, abdominal pain/diarrhea, renal failure, disseminated intravascular coagulation
4. Diagnosis
Serologic tests available
Made clinically, confirmed serologically
1) Indirect immunofluorescent antibody test--most sensitive
Tetracycline 2-3 grams daily given po or IV
b. Chloramphenicol 1.5-2 grams daily given po or W
d. Sulfonamides are contraindicated
1.Transmitted to humans by
-rural disease?
what forms at bite site
-whats a worse disease, RMSF or rickettsialpox?
4. Diagnosis and treatment
the painless bite of the mouse mite; urban as opposed to rural disease.
2. Eschar forms at the bite site 3-7 days before the onset of fever, chills and headache. Rash that follows is papulovesicular (bumps that turn into blisters), not petechial.
3. Compared to RMSF, disease is mild.
- same as above.
Louse-borne typhus:
prototype of the typhus group caused by R. prowazekii
2. Disease is spread from person to person
-is a reservoir of R. prowazekii in the Eastern U.S.
by the body louse.
The southern flying squirrel
process of Rash
begins on the trunk in the axillary folds and moves distally until the
entire body is covered
A recrudescent form of the disease called
Brill-Zinsser disease has been seen in immigrants and Veteran's of WW II.
1. Caused by R. typhi and found worldwide; most cases in the U.S. are found in southern
Texas and California.
2. Transmitted to humans by
Murine typhus
flea bites.
EHRLlCHIA chaffeensis- (Human Monocytic Ehrlichiosis
-transmitted by?

-prevalance compared to RMSF
1. transmitted by tick vector
-fever, headache, nausea, vomitin, chills
2. Rash is infrequent
-doxycyclin, chloramphenicol is not effective
. ANAPLASMA Phaqocytophilum (Formerly Human Granulocytic Ehrlichiosis)
-linked to the bites
. Treatment
of the deer tick Ixodes scapularis and the dog tick

Etiologic agent
- is not an
A. Coxiella burnetii, which
-obligate intracellular parasite
C. burnetii is transmitted to humans by inhalation of contaminated particles, usually in association with cattle, sheep, goats or through ingestion of raw or contaminated milk.
Clinical Manifestations 1. Acute infection
b. Two characteristic features of acute infection
-Chronic infection
a. Incubation period 2 to 6 weeks, followed by abrupt onset of fever (>38.5°C), severe headache, malaise, myalgias. Unlike other rickettsial diseases, rash is absent. include atypical pneumonia and hepatitis.
2. : Develops in <1 % of patients infected with Q fever
a. Endocarditis is the most frequently described entity.
b. Most patients have predisposing valvular heart disease
1. Bartonellosis
a.Two clinical manifestations
b. bacilliformis
1 )Oroya fever: Severe anemia
2)Verruga Peruana: Hemangiomatous nodules
c. Transmitted by bites of
sand flies that inhabit the high Andes of Peru
-bacteria adhere to red blood cells and deform them, producing anemia
f.1) chloramphenicol
2) blood transfusions for severe anemia
. Trench Fever
a. Caused by
-WWI because
-present day
B. quintana

-of louse infestation of soldiers "in the trenches
c. Syndrome
1) relapsing high fever
2) generalized myalgias with focal shin pain
3) headache
. Cat scratch disease
Caused by
a. Bartonella hense/ae and Bartonella c/arridgeiae
b. Epidemiology
1) cat-associated fleas may be important
-cat scrathces
Clinical manifestations
1) 3-10 days after the cat scratches a pustule or papule forms at the site of inoculation
2) low grade lever, malaise and fatigue may occur
becomes the major manifestation-usually develops
regional lymphadenopathy

in 1 to 7 weeks
over several months
3 of the following
contact with cat
-+ blood test
-neg for other causes of lymphadenopathy
-histopahtology of skin node
endocardiditis can be caused by which Bartonellas?
-typically causes infection in what pt
-causes what

-imunocompromised AIDS
-angiomatosis;a proliferative disease of small blood vessels of the skin and

-peliosis;characterized by numerous blood-filled cystic structures of the
viscera especially the liver and spleen
a. CSD—usually self-limiting illness and antibiotics are given only in severely ill or
complicated cases; choice of antimicrobial therapy is unclear

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