Chlamydia and Rickettsiae-Vishy Flashcards
What does Chlamydia trachomatis cause (3)?
genital tract infections, eye and respiratory infections.
What do serotypes A-C of Chlamydia trachomatis cause? How is this infection characterized? How do you get infected? Where is this bacteria found?
Causes Trachoma- endemic blinding
Trachoma characterized by: infection, inflammation, scarring of conjunctivitis and sometimes blindness
•Infection occurs via flies, gnats and dirty hands and towels to the eye.
•Found in hot and dry developing countries.
What do serotypes D-K of Chlamydia trachomatis cause? How do you get infected? What can it cause in neonates? What is the individual usually co-infected with?
Cause STDs (urethritis in men, cervicitis and salpingitis in women).
•Can be transmitted to eyes and respiratory tract.
•Infection via sexual contact.
•Usually co-infected with Neisseria gonorrhoeae.
•Can lead to infertility in women.
•Newborns can pick up the bacteria from mom while going thru the birth canal. Results in inclusion conjunctivitis or neonatal pneumonia.
What does serotype L of Chlamydia trachomatis cause?
Cause STDs (lymphogranuloma and venereum) •Lymphogranuloma: STD with lesions on genitalia and infection and inflammation in lymph nodes.
What does Chlamydia/Chlamydophila psittaci cause? How do you get infected? Is person-person transmission common?
Causes psittacosis-Infection via inhalation of bird excrement or feathers leading to respiratory infection.
•Person-to-person transmission is not common.
•Only 1 immunotype.
What does Chlamydia/Chlamydophila pneumoniae cause?
Causes atypical pneumonia-Atypical pneumonia is less severe and self-limiting.
•Aka walking pneumonia (they can actually walk to the hospital).
•Can cause bronchitis and pneumonia.
•Only 1 immunotype.
What are the bacterial properties of Chlamydiae?
- Obligate intracellular pathogens of humans, animals & birds
- Are non-motile, gram negative; share antigens, have both DNA and RNA and cannot multiply outside living cells/ tissues (like viruses)
- Cannot synthesize ATP – depends on host cell for energy & nutrient sources. Hence, called obligate intracellular pathogens.
- Susceptible to antibacterial antibiotics but not penicillins or cephalosporins
- Multiply by binary fission, with a complex developmental cycle
- Size—3 mm, just at the limit of resolution using light microscopy
- Gram-negative type cell wall with typical LPS, but NO peptidoglycan
- Typically infect epithelial cells of the mucous membranes.
What is the replication cycle of Chlamydiae?
- Elementary body infects epithelial cells.
oInert and metabolically inactive spore-like form.
oBecomes intracellular thru phagocytosis by macrophages. - EB swells to form a reticulate body.
- RB fills the infected cell’s cytoplasm, divides several times and then returns to EB form for release and cycle repeats.
oThe RB is inside an inclusion body.
oThe inclusion body is made up of glycogen in Chlamydia trachomatis (different in the other 2 types). - Each EB produces 50-200 new EBs.
What is our immune system response to Chlamydiae infection?
Our antibodies produced in response to the bacteria cross-react with our own self antigens present in cells of eyes, joints and urethra, leading to inflammation, arthritis, urethritis and uveitis (called Reiter’s syndrome).
*Found in C. trachomatis.
What are the Lab diagnostics used to confirm Chlamydiae infection?
- DNA amplification (PCR)-Take a swab
- Can look at inclusion bodies to determine which type of Chlamydia.
•Chlamydia trachomatis forms glycogen inclusions •C. psittaci and C. pneumoniae do not form glycogen inclusions. - Can also use, fluorescent antibody staining, DNA hybridization, ELISA and serological testing.
What is the treatment for Chlamydiae trachomatis infection? What is the treatment for Chlamydiae psittaci and pneumoniae infections? What is the treatment for neonatal conjunctivitis caused by Chlamydiae infections? Is there any type of prevention available?
- Chlamydia trachomatis: Azithromycin (due to co-infection with gonococci) and erythromycin
- Chlamydia psittaci and pneumoniae: Tetracyclines like doxycycline.
- For neonatal conjunctivitis: erythromycin.
Prevention- No vaccine.
What does Rickettsia rickettsia cause? What is the progression of the illness? How is it transmitted? What is the lifecycle?
Results in Rocky Mountain Fever.
•First you get myalgias, HA and fever.
•Get a local lesion after 2-6 days from bitten. Then swelling, redness and edema.
•Lesion spreads from hands → legs → trunk
Transmitted from dog to tick to human.
•Tick = Dermacentor (commonly found on East coast)
•No person-to-person transmission.
Life cycle: transovarian cycle
•From the adult tick it gets transmitted to the eggs and from the eggs to nymph and finally from the nymph to the adult tick. Therefore it is continuously maintained in the ticks.
What does Rickettsia prowazekii cause? How is it transmitted? What is the progression of the illness? What is the recurrent form called? Who does it effect?
Causes epidemic typhus.
•Transmitted from humans to humans via human louse Pediculus. The bacteria multiples inside the gut epithelium of the insect.
•Lesions first appear in trunk → hands → legs. Face, palm and soles are spared.
•Brill-Zinsser attack: (recurrent form). Seen in elderly individuals who were in war. Relapsing form of epidemic typhus fever (much less severe).
What does Coxiella brunetti (Rickettsia) cause? How is it transmitted? What is the vector? Who gets it? What is the progression of the illness? What are the symptoms? What can it lead to?
Results in Q fever-Transmitted via inhalation of aerosol particles w/ bacteria.
Vector = cattle or sheep.
Released in large quantities in milk and placenta.
Disease common in those who work with livestock, dairy and vets.
•Granuloma formation in lungs → liver → spleen.
•Symptoms: fever, cough, HA and myalgia.
•Can lead to pneumonia and hepatitis.
What are the bacterial features of Rickettsia?
- Gram negative rods (barely visible by light microscope)
- Class G- cell wall, thin PG layer.
- Must be grown w/n living tissue or tissue culture cells.
- Obligate intracellular parasites.
- Binary fission mode of division.
