Chapter 13: Chlamydia, Rickettsia, and Friends

Question 1

What are two groups of gram-negative bacteria that are obligate intracellular parasites?

Answer 1

Chlamydia and Rickettsia

Question 2

How does Chlamydia and Rickettsia obtain energy?

Answer 2

energy parasites
Use ATP/ADP translocater to steal ATP from Host cell
Rickettsia can creat ATP

Question 3

How does Chlamydia spread?

Answer 3

person-to-person contact

Question 4

How does Rickettsia spread?

Answer 4

by arthropod vector (requirement except for Q fever)

Question 5

Unlike other gram-negative bacteria, what does chlamydia not have?

Answer 5

Peptidoglycan layer and no muramic acid

Question 6

What are the two forms of Chlamydia during its lifecycle?

Answer 6

Elementary body: inert, dense, round, small, infectious 
Initial body (reticulate): grows, RNA content increases, binary fission, steals ATP, replicates in endosomes (inclusion)

Question 7

What does Chlamydia trachomatis primarily infect?

Answer 7

eyes: trachoma - chronic conjunctivitis that is the leading cause of preventable blindness in the world

and genitals

Question 8

How is Chlamydia trachomatis transmitted?

Answer 8

hand-tohand transfer of infected eye secretions

Sexually transmitted and through birth canal

Question 9

Chlamydia trachomatis serotypes A, B and C cause

Answer 9

Trachoma

Question 10

Chlamydia trachomatis serotypes D-K cause..

Answer 10

Inclusion conjunctivitis, infant pneumonia, cervicitis, nongonococcal urethritis in men

Question 11

What is the most common sexually transmitted disease?

Answer 11

Nongonococcal urethritis (not caused by Neisseria gonorrhoeae)

Predominantly caused by Chlamydia trachomatis and Ureaplasma urealyticum

Question 12

What is PID? what causes it? What can it lead to?

Answer 12

Pelvic inflammatory Disease: inflamed cervix with yellow mucopurulent endocervical discharge
caused by chlamydia trachomatis and neisseria gonorrhoaea
leads to infertility and higher risk of ectopic pregancy

Question 13

A man with urethritis has a unilateral scrotal swelling, tenderness and pain. Fever. What is the likely cause?

Answer 13

chlamydial epididymitis caused by Chalmydia trachomatis

Question 14

What is Reiter’s syndrome? What is it caused by?

Answer 14

inflammatory arthritis of large joints, that occurs in young men 20-40. Inflammation of the eyes and urethritis

Chlamydia trachomatis

Question 15

What is Fits-Hugh-Curtis syndrome ? What is it usually associated with?

Answer 15

infection of liver capsule with symptoms of right upper quadrant pain that can occur in men and women

Chlamydial or gonococcal infection

Question 16

What does Chlamydia trachomatis serotypes L1-L3 cause?

Answer 16

Lymphogranuloma venereum
Painless bump or ulceration on genitals that heals
Lymph nodes enlarge and become tender and may break open and drain pus

Sexually transmitted

Question 17

What is psittacosis?

Answer 17

An atypical pneumonia that occurs 1-3 weeks after exposure to carrier pigeons or other birds (dust of feathers or dried feces)

Caused by Chlamydophila psittaci

Question 18

Chlamydophila pneumoniae –>

Answer 18

Atypical pneumonia in young adults worldwide (along with Mycoplasma pneumoniae)
Single species - TWAR

Question 19

Describe Rickettsia

Answer 19

small, gram negative, non-motile rod/coccoid shaped

Obligate intracellular energy parasites

Question 20

Where does Rickettsia replicate?

Answer 20

Freely in the cytoplasm

Question 21

What surface does Chlamydia prefer?

Answer 21

columnar epithelium (line mucous membranes)

Question 22

What surface does Rickettsia prefer?

Answer 22

Endothelial cells that line blood vessels

Question 23

Rickettsia shares the same antigenic characteristics with what other type of bacteria?

Answer 23

Proteus vulgaris bacteria

OX-2, OX-19, OX-K

Question 24

What is the Weil-Felix reaction?

Answer 24

Cross-reacting Proteus vulgaris antigens to help confirm a diagnosis of rickettsial infection

Mis serum of a pts suspected of rickettsial disease with antigens from specific strains of Proteus vulgaris

Positive test: latex beads coated with Proteus antigens with agglutinate

Question 25

Pts comes in with fever, conjunctival redness, headache and a rash that started on his ankles but has spread to his trunk. Pt had just returned from a hiking trip in North Carolina. What is the most likely diagnosis and cause?

Answer 25

Rocky Mountain Spotted Fever (OX-19, OX-2) Caused by Rickettsia rickettsii - damages endothelial lining of blood vessels causeing small hemorrhages and thrombi Wood tick or dog tick Ricky is riding a wood tick..... *Note: more common in southeastern U.S that in the rocky mountains. but cases have been reported in nearly every state

Question 26

Pt comes in with blisters and headache Red skin bump turned into blister and more appeared on the body later.(similar to chickenpox) Fever also present. What is a possible diagnosis?

Answer 26

Rickettsia akari Rickettsialpox Spread by mites that live on house mice

Question 27

You are at your desk at CDC when a report is given to you. A few towns in southern U.S had a sudden abrupt onset of fever and headache, small pink macules appeared on the trunk and then the entire body. Some have become delirious. Disease keeps resolving after almost a month but some pts get gangrene of the feet and hands. Some older pts have died. You are told to investigate the cause and the source of the disease. What is your suspicion?

Answer 27

Epidemic typhus caused by Rickettsia prowazekii Note: epidemic = sudden onset and rapid spread of an infection that affects a large proportion of the population Source: Flying squirrels carrying lice and fleas

Question 28

What two Rickettsia bacteria are so closely related, cause similar disease, and infection with one confers immunity to the other?

Answer 28

``` Epidemic typhus (rickettsia prwoazekii) Endemic typhus (Rickettsia typhi) ``` Both share the OX-19

Question 29

Disease is carried by rat flea, after 10 days there is a fever, headache and flat, sometimes bumpy, rash Endemic. What is the disease and culprit?

Answer 29

Endemic or Murine Typhus Rickettsia typhi Endemic: infectious disease that exists contantly throughout a population

Question 30

Untreated Rickettsia prowazekii can lead to what?

Answer 30

latent state of the bacteria and can break out of latent state to produce Brill-zinsser disease ``` Symptoms milder (no skin rash) bc of antibodies Rapid rise of IgG titer ```

Question 31

Which Rickettsia is found in Asia and southwest pacific and spread by the bite of larvae (chiggers) of mites? What are the symptoms?

Answer 31

Rickettsia tsutsugamushi Sumo wrestler Ricky Tsutsugamushi walking in the scrub being bitten by chiggers after 2-weeks, high fever, headache, and scab at original bite site. Later a flat or bumpy rash

Question 32

Which Ricky causes fever, headaches, eshars and regional lymphadenopathy? Found in southeastern coastal US

Answer 32

Rickettsia parkeri

Question 33

What organism is responsible for African tick-bite fever?

Answer 33

Rickettsia africae | Travel-related ricettsiosis: unexplained fever after travel

Question 34

What disease causes high fevers, rash, headache, and severe back and leg pains; after appearing to recover, relapse 5 days later; fatalities are rare; carried by louse? Disease that occurred during WWI

Answer 34

Bartonella quintana - Trench Fever Rickettsia-like but is NOT an obligate intracellular organism

Question 35

Pt comes in with low-grade fever and malaise. You notice scratches on her arm and she claims it was from a cat. Lymph nodes near scratch are enlarged. What is the most likely cause?

Answer 35

Bartonella henselae | Cat-scratch disease

Question 36

How is Coxiella burnetti similar to gram-positive bacteria Clostridium and Bacillus?

Answer 36

has an endospore form

Question 37

What does the endospore form of Coxiella burnetti allow it to do?

Answer 37

Resistance to heat and drying Extracellular existence: extended survival outside host cell Non-arthropod transmission: grows in ticks and cattle, remain viable in dried tick feces and cattle hides. Aerosolized and inhaled Pneumonia: able to be inhaled into lungs -->mild pneumonia

Question 38

What is the ONLY rickettsial disease that causes pneumonia and there is NO rash?

Answer 38

Coxiella burnetti

Question 39

Pneumonias caused by viruses, Mycoplasma penumoniae, and Chlymydophila have frequently been called what?

Answer 39

Atypical Pneumonia