Chapter 13: Chlamydia, Rickettsia, and Friends Flashcards Preview

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Flashcards in Chapter 13: Chlamydia, Rickettsia, and Friends Deck (39):

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

Chlamydia and Rickettsia


How does Chlamydia and Rickettsia obtain energy?

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


How does Chlamydia spread?

person-to-person contact


How does Rickettsia spread?

by arthropod vector (requirement except for Q fever)


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

Peptidoglycan layer and no muramic acid


What are the two forms of Chlamydia during its lifecycle?

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


What does Chlamydia trachomatis primarily infect?

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

and genitals


How is Chlamydia trachomatis transmitted?

hand-tohand transfer of infected eye secretions
Sexually transmitted and through birth canal


Chlamydia trachomatis serotypes A, B and C cause



Chlamydia trachomatis serotypes D-K cause..

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


What is the most common sexually transmitted disease?

Nongonococcal urethritis (not caused by Neisseria gonorrhoeae)

Predominantly caused by Chlamydia trachomatis and Ureaplasma urealyticum


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

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


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

chlamydial epididymitis caused by Chalmydia trachomatis


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

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

Chlamydia trachomatis


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

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

Chlamydial or gonococcal infection


What does Chlamydia trachomatis serotypes L1-L3 cause?

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


What is psittacosis?

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


Chlamydophila pneumoniae -->

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


Describe Rickettsia

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

Obligate intracellular energy parasites


Where does Rickettsia replicate?

Freely in the cytoplasm


What surface does Chlamydia prefer?

columnar epithelium (line mucous membranes)


What surface does Rickettsia prefer?

Endothelial cells that line blood vessels


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

Proteus vulgaris bacteria

OX-2, OX-19, OX-K


What is the Weil-Felix reaction?

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


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?

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


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?

Rickettsia akari
Spread by mites that live on house mice


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?

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


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

Epidemic typhus (rickettsia prwoazekii)
Endemic typhus (Rickettsia typhi)

Both share the OX-19


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?

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


Untreated Rickettsia prowazekii can lead to what?

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


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

What are the symptoms?

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


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

Rickettsia parkeri


What organism is responsible for African tick-bite fever?

Rickettsia africae
Travel-related ricettsiosis: unexplained fever after travel


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

Bartonella quintana - Trench Fever

Rickettsia-like but is NOT an obligate intracellular organism


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?

Bartonella henselae
Cat-scratch disease


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

has an endospore form


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

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


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

Coxiella burnetti


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

Atypical Pneumonia