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Clinical Microbiology > Section 6: Rickettsiae > Flashcards

Section 6: Rickettsiae Flashcards

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Biology 101 flashcards
1
Q

What are the characteristics of Rickettsiae

A

• Very small Gram negative coccobacilli
• Obligate intracellular parasites-needs cell for materials to synthesize A TP
• Unable to metabolize glucose
• Can be grown in the laboratory in chick embryo yolk sacs
• Some Rickettsiae share antigens with Proteus strains
-Historically use Weil-Felix test to diagnosis Rickettsiae, no longer used-insensitive

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2
Q

What are the 2 types of Rickettsial diseases

A

Group I -Typhus

GroupII - Spotted fevers

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3
Q

What is Rickettsia prowazeki

A

Epidemic Typhus

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4
Q

What is the vector for Rickettsia prowazeki

A
  • Vector is lice, associated with poor sanitation -

- Reservoir in U.S. is flying squirrels -last epidemic was 70 yrs. Ago

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5
Q

What is the pathology of Rickettsia prowazeki

A
  • Clinical symptoms due to bacteremia
  • High fever, chills, muscle pain
  • Macular rash (not on soles or palms)-only in 40% of patients
  • Generally resolves in 3 weeks, but is occasionally fatal
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6
Q

How is Rickettsia prowazeki diagnosed

A

IFA test (indirect fluorescent antibody)

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7
Q

What is Brill-Zinsser Disease

A

Hans Zinsser discovered that those NOT treated with antibiotics retain R. prowazeki in a latent state

  • Occasionally breaks out oflatent state to cause Brill-Zinsser disease, milder form of epidemic typhus
  • No skin rash
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8
Q

What is Rickettsia typhi

A

endemic Typhus

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9
Q

What is the vector for Rickettsia typhi

A

fleas, rodents are primary reservoir

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10
Q

What is scrub typhus

A

Caused by Orientia (formerly Rickettsia) tsutsugamushi

  • Transmitted by larva of mites (chiggers which live in soil)
  • Rodent reservoir
  • Affected soldiers in WWII and Vietnam
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11
Q

What is the pathology of scrub typhus

A

High fever, severe headache

-Eschar (resembling a cigarette burn) forms at initial bite site followed by maculopapular rash

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12
Q

What is Rickettsia rickettsii

A

Rocky Mountain spotted fever

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13
Q

What is the epidemiology of Rickettsia rickettsii

A

Vector is the spotted wood tick

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14
Q

What is the pathology of Rickettsia rickettsii

A
  • Fever
  • Severe headache
  • Maculopapular rash-with discolored spots from small hemorrhages
  • Rash seen first on palms, soles of feet and wrists. Then spreads over body
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15
Q

What are Rickettsialpox caused by

A

Rickettsia akari

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16
Q

What is the vector for Rickettsia akari

A

mites that love on house mice

17
Q

What are the symptoms for Rickettsia akari

A

Mild chills and fever
• Initial bump at bite, turns into vesicle
• Vesicles spread over body (similar to chickenpox)

18
Q

What is trench fever

A

Rickettsia Quintana

19
Q

What is the epidemiology of Rickettsia Quintana

A
  • Only member of this genus grown in lab
  • Most prevalent disease among Allied troops serving in the trenches during WWI.
  • Current incidence is unknown, occurs in homeless population
  • The body louse, Pediculus humanus, transmits classic trench fever
20
Q

What is the pathology of Trench fever

A
  • Fever can reach I 05°F ( 40.5°C) and stays high for five to six days at a time. The temperature then drops, and stays down for several days, usually recurring in five-to six-day cycles. An individual may experience as many as eight cycles of fever with the illness
  • Skin rash is common
21
Q

What is Q Fever

A

Coxiella burnetii

22
Q

What is the epidemiology of Q fever

A
  • Not transmitted by an arthropod
  • Unusual because has an endospore form
  • Cattle, sheep, and goats are the primary reservoirs of C. burnetii
  • Bacteria are excreted in milk, urine, and feces of infected animals.
  • Most importantly, during birthing bacteria are shed in high numbers within the amniotic fluids and the placenta.
  • Endospores are resistant to heat, drying, and many common disinfectants.
  • Inhale endospore from contaminated air
23
Q

What is the pathology of Q fever

A
  • Fever, chills, headache
  • Develop atypical pneumonia
  • NO skin rash
  • Q fever outbreaks have resulted mainly from occupational exposure: veterinarians, meat processing plant workers, sheep and dairy workers, livestock farmers, and researchers at facilities housing sheep

Clinical Microbiology (6 decks)

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