Chylamidia

Question 1

What are the 3 types of Chlamydiae discussed?

Answer 1

C. trachomatis
Chlamydophila psittaci
Chalmydophila pneumoniae

Question 2

List the important properties of Chlamydiae

Answer 2

1. Obligate intracellular pathogens
2. non-motile, gram -
3. contain DNA and RNA
4. can withstand PNC and Cephs, but susceptible to others
5. cell wall lacks peptidoglycan, has LPS

Question 3

What is the life cycle?

Answer 3

1. Spore (elementary body) infects host
2. ingested into macrophages/lymphocytes
3. in cell, turns into reticulate body (active)
4. multiplies via binary fission

Question 4

what is the inclusion membrane?

Answer 4

used to distinguish between trachomatis (has peptidoglycan) and psittaci/pneumonia (no glycogen)

Question 5

What does each species of Chlamydia Cause?

Answer 5

C. trachomatis (A-C) causes trachoma, endemic blining
C. trachomatis (D-K) causes stds (urethritis, cervicits, neonatal pneumonia via birth, conjunctivitis via birth)
C. trachomatis (l1-L3) causes Stds
C. psittaci cuases psittacosis
C. pneumoniae causes atypicial “walking” pneumonia

Question 6

How is C. trachomatis (A-C) spread?

Resevoir?

Sympotoms?

how to diagnose;

Where does it occur?

Answer 6

Caused by Chlamydia trachomatis (A-C)

Spread via fingers/touch, fomites, and flies

Humans only

keratoconjunctivits, corneal pannus

miscroscopic exam - look for inclusion bodies

Occurs in hot, dry enviro (N. Africa/ asia)

Question 7

What co-infects w/ Chlamydia trach?

Answer 7

Neiserria

Question 8

What are the 4 stages of Trachoma?

Answer 8

1. Keratitis w/ exudate (protein rich fluid)
2. trichiasis - eyelashes grow into eye
3. scarring of conjunctiva
4. Blood vessel growth in cornea?

Question 9

What causes STD chlamydia?

What are symptoms?

Answer 9

STD caused by trachomatis d-L

Can present as:

• males*: urethritis, prostitis, epididymitis (90% sympotmatic)
• females* (mostly asymptomatic): cervicitis, , proctitis, PID salpinigitis (–>ectopic pregnancy, infertilitiy)

Can infect newborns via conjunctivitis or pneumonia

May cause scarring in host by antibody binding to hsp60

Question 10

What causes inclusion conjunctivitis?

What is the resevior, and how is it spread?

How to diagnose?

What is Reiter’s syndome?

Answer 10

Caused by C. trachomatis (D-K)

Only in humans, spread by fomites of STDs. (Infant - acquired)

Microscopic obersvation for inclusion bodies.

Reiters: arthritis, urethritis, uveitis - cuased by antibodies self-reacting w/ self antigens.

Question 11

What is LGV?

Answer 11

Lymphogranuloma venerum - cuased by c. trachomatis L1-3

Presents as swollen lymph nodes near genitals

Question 12

what cuases Psittacosis?

How does it spread?

What are its symptoms?

Answer 12

Caused by C. psittaci

Comes from birds, inhalation of infectious excrement.

Atypical pneumonia - lower fever, little sputum, very mild pneumonia

Question 13

How does c. pneumonia present?

How are symptoms related?

Answer 13

It appears in only 10% of those infected as mild URI/LRI.
In people of 60, up to 70% become symtpomatic.

Can be related to plaque formation, MS, asthma, rheumatoid arthritis.

Question 14

describe laboratory diagnosis

Answer 14

Convalescent (chronic) pt serum has 4x antibody titer as acute.

c. trachomastits infected cells have glycogen filled inclusion bodies - use idoine/giemsa stainning
* can’t use for other Chlamydias*

PCR important (use NAAT for diagnosis of C. trachomasitis and Neisseira)

Question 15

What are the 3 species of rickettsia

Answer 15

1/ Rickettisa rickettsii - Rocky mountain spotted fever

2. coxiella burnetti - Q fever
3. Rickettsia prowazekii - Epidemic Typhus (developing countries)

Question 16

what are the characteristics of Rickettisa

Answer 16

Gram - rod that is obligate intracellular parasite that replicates via binary fission

Question 17

How does it invade host?

What is Weil-Felix rxn?

Answer 17

1. enter’s skin through arthropod bite
2. Infects endothelial cells (causes petchial rash via thrombi)
3. replicates via binary division

WF rxn: reckettsia antibodies attach/rxn to membrane of proteus vulgaris–> cause agglutination rxn in serum

Question 18

What is Rickettsia’s pathogenesis?

Answer 18

In endothelial cells, cuases hyperplasia and thrombi
can cause Petechial rash in skin (via hemorrhage)

Increase in vascular permeability via LPS–>septic shock

DIC: Ricketssial endotoxin

Question 19

How does ricketssia resist immune system?

Answer 19

If eaten by macrophage/ phagosome, can exit phagosome and remain in cytoplasm w/o a membrane covering–> no detection

Question 20

How is RMSF spread?

How does it present?

Answer 20

RMSF lives in ticks, lives on rodent via trans ovarian route (via eggs). Vector is the tick.

Presents as rash on palm of hands/soles of feet, moves to trunk.

Can cause vascular coagulation–> death

Question 21

How is the resevoir of Q fever?

How does it spread?

Answer 21

Coxiella burnietti, originally from sheep, as spore form.

Spreads to humans as spore throuhgh infected tissue, milk in large quantities.

In healthy hosts, no disease.

In immunocompromised, can have pneumonia–>disseminated (endocarditis/hepatitis/ sock)

Question 22

What cuases typhus?

How is it spread?

What are the symptoms?

How to test/diagnose?

Answer 22

Typhus caused by Rickettsia prowazekii. Its resevoir is the pedicus louse (GI), which also spread the infection. Invades endothelial cells (in vessels)
VIRUS ONLY IN HUMANS.

Symptoms: rash starts on trunk, moves to hands and legs (no palms/soles)

Test: Elisa for IgM Ab (1 wk), and PCR.

Does not exist in US endemically.

Question 23

What is Brill-zinsser rxn?

Answer 23

Antibodies of typhus cross react w/ receptors on surface of cells, causes agglutination.

Shows up as Ab -, but can cause relapse of fever.

Question 24

What is appropriate prevention of the ricketsii diseases?

Answer 24

Vector control
RMSF - has no vaccine
Q fever- heat killed vaccine
typhus - formalin killed vaccine

If Dogs have, give DDT to kill louse.