Lecture 23 Chlamydia and Rickettsia Flashcards
Why is Chlamydia and rickettsia grouped together?
- not genetically similar
- grouped because of unique lifestyle (obligate intracellular bacteria)
What are the three species of Chlamydia?
- Chlamydia trachmomitis
- Chlamydophila pneumoniae
- Chlamydophila psittaci
What are some sx of contracting chlamydia Trachomatis?
-urogenital infections, ocular infections
What are some sx of C. Pneomoniae?
Respiratory tract infections
What are sx of C psittaci?
-Pneumonia, systemic infections (from birds)
What is the Elementary body of Chlamydia?
- spore-like form (non-replicating)
- ***infectious
- stabilized by disulfide crosslinking of outermembrane proteins
What is the reticulate body of Chlamydia?
- intracellular replicating form
- divide within membrane-bound inclusion
- osmotically unstable, cannot survive outside cell
- ***non-infectious
What can be said of the genome of Chlamydia?
- small chromosome
- auxotrophic for several aa and nucleoside triphosphate (can produce limited ATP, encodes two translocases)
- highly conserved endogenous plasmid required for full virulence
What virulence factor is expressed both in the EB and RB of chlamydia?
-Type III secretion system
what is the pathogenesis of EB chylamadia?
- induces Epithelial cell internalization
- pre-formed effector protein (TARP), secreted into target cell
- TARP induces actin polymerization, phago of EB
What is the pathogenesis of Chlamydia?
secrete
- Inc proteins: modify inclusion membrane
- CPAF: Translocated proteases that degrade host and Chlamydia proteins
- Anti-apoptotic factors secreted by chlamydia keep host alive until matures
What does the modification of chlamydia inclusion membrane do for the pathogen?
- prevent lysosome fusion by blocking SNARE-mediated interactions
- co-opt trans-golgi vesicles to camouflage growing inclusion
What is the immune response to C trachomatis (infects epithelial cells of conjuctiva, respiratory, GI, Urogenital)?
- TH1 (interferon-y-associated) immune response
- provokes a low level chronic inflammatory response
- necrosis, cell proliferation, scar tissue formation
- leads to disease
How are the servovars of C trachomatis determined?
-polymorphic outer membrane proteins, can associate servavors to diseases
What are diseases caused by C trachomatis?
-trachoma
-Urethritis/cervicitis
-perinatal infactions
inclusion of conjunctivitis
-Lymphogranuloma venereum
How do C Trachomitis servovars differ in release from epithelial cells?
- some release apical to lumen (A-K)
- some release baolateral into lymph nodes (LGV)
What age group is more prone to C Trachomitis?
-20-24, more so in women
What are the sx of C trach urogenital infection in men?
- Urethritis:
- Dysuria and urethral discharge
- More likely to be asymptomatic than gonorrhea
- Epididymitis- frequently unilateral
What of some sx of urogenital infection in women by C trach?
- dysuria, frequency
- absence of WBC in the urine
What are some sx of Cervicitis?
- most women asymptomatic
- Mucopurulent cervical discharge
- Friability (easily induced bleeding)
- Untreated infections persist for months
Whatare the Pelvic inflammatory diseases (PID)?
- Endometritis (uterine lining)
- Salpingitis (fallopian tubes)
- Peritonitis (peritoneal cavity)
What some sx of PID?
- discharge, bleeding, fever, abd tenderness, and pain.
- Symptomatic PID can occurs in women with endocervical C trach infections
- can result in scar tissue (tubal infertility, ectopic pregnancy, chronic pelvic pain)
What are some diseases caused by C trach Neonatal infections?
- inclusion conjunctivitis
- Pneumonia
What are the sx of inclusion conjunctivitis?
-watery discharge becomes purulent, eylids swell, conjuctiva become red and thickened
How is C tach Dx?
-Nucleic acid amplification techniques (NAAT)
(High sensitivity, specific, urine or vaginal swab)
-Screenings (CDC recommended),
MSM (for urethral and reactal)
How is Lymphogranuloma venereum (LGV) transmitted?
- caused by serovors L 1-3
- STD
- lympotropic, meaning capable of regional and systematic dissemination
What are the stages of LGV?
- Primary stage: small ulcer on genitals, few, rapidly heals
- secondary stage: inguinal lymphadenophathy, fever, HA, muscle pain, resolves after week w/ possible scars
- Tertiary stage: Chronic procto-colitis, mimic inflammatory bowel diseases. Elephantiasis of genitalia can occur.
What is the pathogenesis for trachoma disease?
- by servovars A-C, not the same as genital
- inital infection in ocular or nasopharyngeal cells
- severity from repeated reinfections
What is the sx of trachoma?
- chronic follicular conjunctivitis
- Progresses to thickening of eyelids, with papillary hypertrophy (bumps in eyelids), contraction of scarred tissue
- Trichiasis- eyelashes turn in, scratch cornea
- Ulceration and scarring of cornea, loss of vision
Where is the highest prevalence of Trachoma?
- sub-Saharan AFrica, SE Asia
- most active in children,
How is trachoma transmitted?
eye and nasopharyngeal secretions in hands, flies fomites
What is WHO’s plan for trachoma?
-eliminate by 2020 SAFE: *Surgery to correct Trichiasis *Abx to treat infection *Facial cleanliness *Environmental improvements (water sanitation)
What abx are used to treat Trichoma?
azithromycin
How is pneumonia transmitted?
- Person-to-person, respiratory droplets
- Most infections mild or asymptomatic
- Clinically indistinguishable form other causes
What types of cells does c pneumoniae infect?
- wide range of cells that types may contribute to transport form the lungs to circulation
- associated with atherosclerosis (plaque in arteries)
How is psittacosis transmitted?
-Birds via inhalation (Psittacine birds or poultry)
What are sx of psittacosis?
-ranges from mild fevrile to fatal pneumonia
How is psittacosis prevented?
Quarantine and treatment of imported birds
What animal population has Chlamydia devastated?
- Koala population in AUS
- Ocular and Urogenital infections
- Solutions are culling and serine protease inhibitor
What abx are sued for ocular and genital infections?
- azithromycin
- Doxycycline
- erythromycin for neonatal
What abx are used for PIDs?
- Cephalosporin and doxycycline
- cannot heal scarring
What abx are used for systematic infections?
-Doxycycline
How is Chlamydia treated?
-abx, no vaccine
What are the characteristics of Rickettsiales?
- obligate intracellular
- Gram-negative bacteria
How is Rickettsiales transmitted?
by arthropod vector
What are some common manifestations of Rickettsiales?
-fever, rash, and HA
What are the three groups of Rickettsiales?
- Spotted fever group: R. rickettsii
- Epidemic Typhus group: R. prowazekii
- Ehrlichiaceae Family: E. chaffeensis, Anaplasma phagocytophilum
How is Rocky Mountain Spotted fever transmitted?
- American dog tick
- Rocky mountain wood tick
What is the pathogenesis of Rickettsia rickettsii?
- enter circulation through tick bite
- attach to and invade vascular endothelial cells
- small genome, capable of independent metambolism
- intracellular motility and cell-to-cel spread via actin-based motility
- injury to host cell results to increased vascular permeability
What are some sx of Rocky Mountain Spotted fever?
- fever, muscle pain, severe HA, nausea, vomiting
- Maculopapular rash
- Sever disease involves multiple organ systems
How is Rickettsia rickettsii prevented?
- avoidance and prompt removal of ticks
- transmission takes 24 hours
What abx are given for Rickettsia rickettsii?
Doxycycline
Which pathogen caused a Typhus epidemic?
R. prowazekii
How is typhus transmitted?
Human body lice, infected louse feces transmits into skin through scratching.
In the US it was from fleas and lice of flying squirrels.
What are the sx of typhus?
- Fever, rigors, sever HA, macular rash, pneumonia, progression to delirium, coma, death
- Pts remain latently infected after recovery and reactivation of disease may occur years later?
What pathogens causes Ehrlichionosis?
Ehrlichia chaffeensis and Anaplasma phagocytophilium
What is the pathogenesis of Erhlichiosis?
- obligate intracellular
- infect leukocytes
- Replicate within inclusions
- inhibit phago-lysosomal fusion
How is Erhlichiosis transmitted?
- Tick born:
- Human monocytic erhlichiosis by lone star tick
- human granulocytic anaplasmosis by deer tick
- most cases in South Central US
What are sx of Erhlichiosis?
- clinically similar to Rocky Mountain Spotted fever, without the rash
- Leukopenia, Thrombocytopenia
How is Erhlichiosis treated?
Doxycycline
