Chlamydia, Rickettsia, and Friends

Question 1

C. pneumonia: clinical

Answer 1

• mild URT
• mycoplasma-like pneumonia (“walking”)
• associated with atherosclerotic plaques, asthma, stroke, Alzheimer’s

Question 2

C. pneumonia: carriers

Answer 2

• koala bears (zoonosis)

- high infection rate

Question 3

C. pneumonia: treatment

Answer 3

• usually untreated

- tetracycline

Question 4

C. psittaci: clinical

Answer 4

• “parrot fever”
• acute, SEVERE pneumonia & sepsis
• well-defined lung involvement

Question 5

C. psittaci: carriers

Answer 5

• psittacine birds by bites or feces inhalation

Question 6

C. psittaci: treatment

Answer 6

• tetracycline

- quarantine birds

Question 7

Chlamydia trachomatis: features

Answer 7

• G-, obligate intracellular parasite; not a true PG in cellwalll; 15 serovars based on LPS antigens; 2 forms EB (infective, .3um) & RB (replicative, 1.0um)
• STD or CONTACT transmission

Question 8

Chlamydia trachomatis: clinical

Answer 8

1. Trachoma: infected birth canal OR by contact or mech vector (flies) -> keratinized cornea (pannus) -> trichiasis -> lead to blindness
2. Inclusion Conjunctivitis: not as severe as trachoma (neonates), poss. Resp. complicate 3. Neonatal Pneumonia: no fever; shorness of breath, suspect if along with inclusion conjunct.
3. Chlamydia: co infection with gonorrhea 40%; males – nongonococcal urethritis, epididymitis, prostatitis; self-limiting; females – PID (most common cause), nongonococcal urethritis, cervicitis, salpingitis ! infertility
4. Latent lymphogranuloma venereum: small abcess ! inguinal buboes (fever, pain, block), ddx with plague-never cervical; can cause elephantiasis or bowel obstruction

Question 9

Chlamydia trachomatis: carriers

Answer 9

• leading cause of preventable blindness
• STD most common in developed countries
• tread both localizations (can cross- infect)
• easier to break DS in RB - manifestation depends on serovar

Question 10

Chlamydia trachomatis: virulence

Answer 10

• EBs cause invasiveness via T3SS remodel host cytoskel. - LYSOZYME RESISTANT
• inhibit phagolysosome fusion living/proliferate in endocytic vesicle
• induce cytokine (IL-1) -> inflammation
• live intracellularly for a long time

Question 11

Chlamydia trachomatis: treatment

Answer 11

• vaccine ineffective
• preferred azithromycin (one-dose, oral)
• also TETRACYCLINE or macrolides
• surgery or epilation for trichiasis
• Expedited partner therapy (EPT)
• many asymptomatic so NEED TO SCREEN

Question 12

Rickettsiae: features

Answer 12

• 4 medical groups, small road

Question 13

Rickettsiae: clinical

Answer 13

• obligate intracellular parasite

Question 14

Rickettsiae: carriers

Answer 14

• yolk sac

Question 15

Rickettsiae: virulence

Answer 15

• MOST infectious organism known (1cell) - Cell type tropisms
• Phospholipase A targets cell membranes -Multiply INTRACELLULAR then spread

Question 16

Rickettsiae: treatment

Answer 16

- Remove vector

- Doxycycline – start SOON - Q-fever vaccine (Australia)

Question 17

Typhus group (Rickettsiae): features

Answer 17

G-, R. prowazekii (lice) typhi (flea), akari (mite), Orientalia tsutsugamushi)

Question 18

Typhus group (Rickettsiae): clinical

Answer 18

• grow in host cytoplasm
• parasite vascular endothelium ! vasculitis, rash (CHEST ! extremity) - high fever, severe prostration (R. Prowazeki)
• mild symptoms with R. typhii
• R. akari ! smallpox-like rash (R. pox)

Question 19

Typhus group (Rickettsiae): carriers

Answer 19

• louse or rat flea (Eschar at bite site

Question 20

Spotted Fever group (Rickettsiae): features

Answer 20

G-, R. rickettsii, grow in host cytoplasm

Question 21

Spotted Fever group (Rickettsiae): clinical

Answer 21

• endothelial pathogen, rash on
  EXTREMITIES FIRST ! trunk
• Rocky Mountain Spotted Fever: fever, headache, nausea, vomiting, m., joint, abdominal pains (from organ vasculitis)

Question 22

Spotted Fever group (Rickettsiae): carriers

Answer 22

• Dog-tick or wood-tick

- Maintained in host via transovarian cycle

Question 23

Spotted Fever group (Rickettsiae): virulence

Answer 23

• Escape from phagosome to divide and then lyse cell

- Lyses SMOOTH MUSCLE – Rhabdomyolysis

Question 24

Ehrlichia chaffeensis,

Anaplasma phagocytophilum group: features

Answer 24

NOT G-

Question 25

Ehrlichia chaffeensis,

Anaplasma phagocytophilum group: clinical

Answer 25

• Chlamydia-like (RB-EB), inside monocytes, granulocytes
• Ehrlichia – headache, myalgia, thrombocytopenia, lymphopenia, bone marrow granulomas; usually NOT vasculitis (rash <50%)
• Anaplasma – 10% rash

Question 26

Ehrlichia chaffeensis,

Anaplasma phagocytophilum group: carriers

Answer 26

• Zoonotic infection from ticks (WI, MN)

Question 27

Ehrlichia chaffeensis,

Anaplasma phagocytophilum group: virulence

Answer 27

NO PG OR LPS

• Ehrlichia – immune response (decr. TNF- alpha and increase late in infection) – parasite of MQ and monocytes (leuko.)
• Inhibits fusion with phagolysosome
• Anaplasma – parasite of neutrophils & granulocytes, pathology from immune

Question 28

Coxiella burnetti: features

Answer 28

NOT G-, grow in phagolysosome

Question 29

Coxiella burnetti: clinical

Answer 29

• Q-fever – resembles flu or pneumonia - parasite of endothelial cells, chronic ! endocarditis (those with defective heart valves)
• granulomas in liver, spleen, bone marrow
• Fever with pneumonic/hepatitis 2-3 post-exposure

Question 30

Coxiella burnetti: carriers

Answer 30

• Infected via dust or aerosols from infected animals

- High in placenta

Question 31

Coxiella burnetti: virulence

Answer 31

• Infect lung epithelia

- LIVE INSIDE the phagolysosome (digestive enzyme and pH resistant)

Question 32

Coxiella burnetti: treatment

Answer 32

• Sulfonamides ENRICH growth