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Chapter 12: Chlamydia, Rickettsia, and Friends


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What do Chlamydia and Rickettsia have in common?
1. Obligate intracellular parasites
2. Energy parasites
3. Small size
Describe the Chlamydia life cycle?
Elementary body (EB) enters columnar epithelial cells. Once inside, it transforms into an initial body (IB). After several IBs have formed, some transform back to EB, which can now infect more cells
What are the three species of Chlamydia?
Trachomatis, psittaci, and pneumonia.
Chlamydia trachomatis primarily infects...?
Eyes and genitals
What is inclusion conjunctivitis? How is treated?
Babies delivered through birth canals infected with Chlamydia trachomatis develop conjunctival inflammation. Erythromycin is given prophylactically.
What are the most common causes of urethritis?
1. Nongonococcal - Chlamydia or Ureaplsama urealyticum
2. Nesseria gonorrhoeae
All patients diagnosed with urethritis are treated empirically with...?
Ceftriaxone, followed by doxycycline or azithromycin.
What is the most common symptom of PID? What is the Chandelier sign?
lower abdominal pain. Extreme cervical motion tenderness seen in PID.
What is Reiter's syndrome?
Inflammatory arthritis of large joints caused by Chlamydia trachomatis found most often in young men.
What is Fitz-Hugh-Curtis syndrome?
Infection of the liver capsule (right upper quadrant pain) associated with chlamydial or gonococcal infection
Chlamydia psittaci causes..?
An atypical pneumonia
What are the characteristics of atypical pneumonia?
Fever, headache, and a dry hacking cough without production of yellow sputum. Lung exam is often normal, chest X-ray may show infiltrate.
Rickettsia rickettsii causes? Via which vector?
Rocky Mountain Spotted Fever - fever, conjunctival redness, headache, and rash. Via a wood tick.
What is the Weil-Felix reaction?
A classic test using the cross-reacting Proteus antigens to confirm the diagnosis of a rickettsial infection
What is primary therapy for rickettsial diseases?
Doxycycline and chloramphenicol
Rickettsialpox is caused by..? Vector?
Rickettsia akari, transmitted to humans via mites that live on house mice.
Epidemic typhus is caused by...? Endemic typhus? Which vectors?
Rickettsia prowazekii (louse). Rickettsia typhi (flea).
Epidemic typhus clinical syx?
Abrupt onset of fever and headache following 2-week incubation period. Rash spares the palms, soles, and face (unlike Rocky Mountain)
What's Brill-Zinsser Disease?
Patients who have recovered from epidemic louse-born typhus without antibx can retain the pathogen in a latent state.
Trench fever is caused by..?
Characteristics of Bartonella?
Louse-borne, not an obligate intracellular organism.
Which bugs reach epidemic proportions during war?
Rickettsia prowazekii and Bartonella
What causes cat-scratch disease? Syx?
Bartonella henselae. Low grade fever and malaise.

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