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RICKETTSIA & CHLAMYDIA Hoza, A.S BLS 206
Introduction. <ul><li>Rickettsiae and Chlamydiae- obligate intracellular organisms.(classif. as bacteria) </li></ul><ul><l...
Genera of the Family Rickettsiaceae: 1.Rickettsia -11 spp (do not multiply within vacuoles & do  not parasitize wbcs. 2.  ...
Rickettsia. <ul><li>3.  Coxiella:   </li></ul><ul><ul><li>(1 spp) obligate parasite  </li></ul></ul><ul><ul><li>– grows pr...
Fundamental differences btn  Chlamydiae and rickettsiae. Rickettsiae Chlamydiae Cytochromes +ve No cytochromes Aerobic met...
Similarities <ul><li>Small, pleomorphic  coccobacillary forms </li></ul><ul><li>Obligate intracellular parasites. </li></u...
Structure of Rickettsia. <ul><li>Typical rickettsia </li></ul><ul><ul><li>Very similar to that of gram-negative bacteria. ...
Metabolism <ul><li>In dil.buffered salt soln: </li></ul><ul><ul><li>Unstable, losing both metabolic activity and infectivi...
Growth and Multiplication . <ul><li>Transverse binary fission. </li></ul><ul><li>Under poor nutrition:  </li></ul><ul><ul>...
Host defenses <ul><li>Both Cellular and Humoral immunity may be important. </li></ul>
Epidemiology <ul><li>Endemic (murine) typhus: </li></ul><ul><ul><li>primarily maintained in rodent populations. </li></ul>...
Pathogenicity   <ul><ul><li>Transmittion: via arthropod vectors;  </li></ul></ul><ul><li>Q fever :  </li></ul><ul><ul><li>...
Pathogenesis... <ul><ul><li>The lesions may become necrotic </li></ul></ul><ul><li>Virulence : </li></ul><ul><ul><li>Proba...
Diagnosis. <ul><li>Clinical:  </li></ul><ul><li>These diseases present as: </li></ul><ul><ul><li>febrile illnesses after e...
Diagnosis… <ul><li>Laboratory: </li></ul><ul><li>Macchiavello stain: </li></ul><ul><ul><li>- organisms bright red V blue b...
Diagnosis… <ul><li>Confirmative diagnosis:  </li></ul><ul><li>Serological reaction:(Weil-Felix test): </li></ul><ul><ul><l...
Important Rickettsial diseases of animals  <ul><li>Heartwater: </li></ul><ul><li>Tropical canine Pancytopenia. </li></ul><...
Rickettsia of Public health significance <ul><li>Tick-borne:-  </li></ul><ul><li>Rocky mountain spotted fever ( R.ricketts...
Public health… <ul><li>Louse-borne: </li></ul><ul><li>European epidemic typhus  ( R.prowazekii )  </li></ul><ul><ul><li>-N...
Public health…. <ul><li>2. Cat scratch fever/bacillary angiomatosis  ( Bartonella henselae )  Reservoir  (domestic cat) </...
Treatment & Control <ul><li>Chemotherapeutic:   </li></ul><ul><ul><li>Tetracycline or  </li></ul></ul><ul><ul><li>Chloramp...
Chlamydia General characteristics <ul><li>Species:   trachomatis ,  psittaci   </li></ul><ul><li>The  Chlamydia   </li></u...
Distinctive properties. <ul><li>Have two distinct forms:-  </li></ul><ul><ul><li>Infectious elementary bodies and  </li></...
Distinctive properties… <ul><li>48-72 hours after infection: </li></ul><ul><ul><li>The cell is lysed and  </li></ul></ul><...
Growth and multiplication.
Metabolism. <ul><li>No detectable  flavoproteins or cytochrome. </li></ul><ul><li>Basis of obligate intracelluar parasitis...
Pathogenesis. <ul><li>C. psittaci  is acquired from infected birds, usually via the respiratory route.  </li></ul><ul><li>...
Pathogenesis…. <ul><li>Inclusion conjunctivitis  </li></ul><ul><ul><li>Milder form,  </li></ul></ul><ul><ul><li>Occurs in ...
Host defenses. <ul><li>Chlamydia  induce interferon and are sensitive to it.  </li></ul><ul><li>During infection, antibodi...
Epidemiology. <ul><li>Trachoma: </li></ul><ul><ul><li>prevalent in Africa and Asia,  </li></ul></ul><ul><ul><li>generally ...
Diagnosis <ul><li>Clinical: </li></ul><ul><ul><li>Diagnosis of trachoma is usually good.  </li></ul></ul><ul><ul><li>Genit...
Diagnosis <ul><li>Serological diagnosis: </li></ul><ul><li>Micro-immunofluorescent tests in tears of patients with eye inf...
Treatment and Control. <ul><li>Chlamydia exhibit low pathogenicity in a compromised host. </li></ul><ul><li>Chemotherapeut...
Treatment and control. <ul><li>Immunological:   </li></ul><ul><ul><li>No vaccine – available since specific antibodies fai...
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Rickettsia & chlamydia presentation.

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Transcript of "Rickettsia & chlamydia presentation."

  1. 1. RICKETTSIA & CHLAMYDIA Hoza, A.S BLS 206
  2. 2. Introduction. <ul><li>Rickettsiae and Chlamydiae- obligate intracellular organisms.(classif. as bacteria) </li></ul><ul><li>Rickettsia General features: </li></ul><ul><li>-parasites of gut cells of athropods. </li></ul><ul><li>-transmittion- athropod to animal. </li></ul>
  3. 3. Genera of the Family Rickettsiaceae: 1.Rickettsia -11 spp (do not multiply within vacuoles & do not parasitize wbcs. 2. Ehrlichia: - 2 spp obligate intracellular parasites – do not multiply within vacuoles but do parasitize wbcs.
  4. 4. Rickettsia. <ul><li>3. Coxiella: </li></ul><ul><ul><li>(1 spp) obligate parasite </li></ul></ul><ul><ul><li>– grows preferentially in vacuoles of host cells. </li></ul></ul><ul><li>4. Baartonella </li></ul><ul><ul><li>3 spp </li></ul></ul><ul><ul><li>- intracellular parasite which attacks the rbc. </li></ul></ul>
  5. 5. Fundamental differences btn Chlamydiae and rickettsiae. Rickettsiae Chlamydiae Cytochromes +ve No cytochromes Aerobic metabolism Anaerobic metabolism. Multiply by binary fision. Single development cycle.
  6. 6. Similarities <ul><li>Small, pleomorphic coccobacillary forms </li></ul><ul><li>Obligate intracellular parasites. </li></ul><ul><li>All contain DNA and RNA. </li></ul><ul><li>Susceptible to various antibiotics. </li></ul><ul><li>Cell walls resemble those of Gram –ve bacteria. </li></ul><ul><li>Require exogenous cofactors from animal cells. </li></ul><ul><li>Most grow readily in the yolk sac of embryonated eggs and in cell cultures. </li></ul>
  7. 7. Structure of Rickettsia. <ul><li>Typical rickettsia </li></ul><ul><ul><li>Very similar to that of gram-negative bacteria. </li></ul></ul><ul><li>Typical envelope: </li></ul><ul><ul><li>Innermost cytoplasmic membrane, a thin electron dense rigid cell wall & outer layer </li></ul></ul><ul><li>Cell wall </li></ul><ul><ul><li>Chemically similar to Gram-ve bacteria i.e contains diamino pimelic acid and no techoic acid. </li></ul></ul><ul><li>No discrete nuclear structure. </li></ul>
  8. 8. Metabolism <ul><li>In dil.buffered salt soln: </li></ul><ul><ul><li>Unstable, losing both metabolic activity and infectivity for animal cell. </li></ul></ul><ul><li>In enriched medium: </li></ul><ul><ul><li>Can survive for may hrs. </li></ul></ul><ul><li>Basis for obligate parasitism: </li></ul><ul><ul><li>Require rich cytoplasm to stabilize unusually permeable cell membrane. </li></ul></ul><ul><li>Require exogenous supply of cofactors. </li></ul>
  9. 9. Growth and Multiplication . <ul><li>Transverse binary fission. </li></ul><ul><li>Under poor nutrition: </li></ul><ul><ul><li>long filamentous forms. </li></ul></ul><ul><li>Immediately after division: </li></ul><ul><ul><li>Extensive movements through the cytoplasm of the cell. </li></ul></ul><ul><li>NB: C.burnetii: </li></ul><ul><ul><li>Enclosed in a persistent vacuole during growth and division. </li></ul></ul><ul><li>6-10 daughter cells form within the host cell before ruptures and releases them. </li></ul>
  10. 10. Host defenses <ul><li>Both Cellular and Humoral immunity may be important. </li></ul>
  11. 11. Epidemiology <ul><li>Endemic (murine) typhus: </li></ul><ul><ul><li>primarily maintained in rodent populations. </li></ul></ul><ul><ul><li>transmitted via the flea. </li></ul></ul><ul><ul><li>Humans ( accidental host). </li></ul></ul><ul><li>Spotted fever: </li></ul><ul><ul><li>Found predominantly in animals. </li></ul></ul><ul><ul><li>Transmitted by the tick. </li></ul></ul><ul><ul><li>Humans (accidental hosts). </li></ul></ul><ul><li>Q fever: </li></ul><ul><ul><li>Mostly in animals. </li></ul></ul><ul><ul><li>Humans acquire disease primarily by inhalation of contaminated aerosols. </li></ul></ul><ul><li>Epidemic typhus and trench fever: </li></ul><ul><ul><li>transmitted from human to human via the louse. </li></ul></ul>
  12. 12. Pathogenicity <ul><ul><li>Transmittion: via arthropod vectors; </li></ul></ul><ul><li>Q fever : </li></ul><ul><ul><li>via inhalation or ingestion of contaminated milk or food. </li></ul></ul><ul><li>The bacteria enter host endothelial cells via an induced phagocytosis. </li></ul><ul><ul><li>Phospholipase A may help in penetration. </li></ul></ul><ul><li>Replication of the bacteria causes lysis of the host cell and consequent spread to other cells. </li></ul><ul><li>Initial replication: </li></ul><ul><ul><li>At the site of entry producing a local lesion. </li></ul></ul><ul><ul><li>Followed by dissemination via the vascular system producing vasculitis and a skin rash. </li></ul></ul>
  13. 13. Pathogenesis... <ul><ul><li>The lesions may become necrotic </li></ul></ul><ul><li>Virulence : </li></ul><ul><ul><li>Probably due to many factors including: </li></ul></ul><ul><ul><ul><li>release of endotoxin, </li></ul></ul></ul><ul><ul><ul><li>production of immune complexes </li></ul></ul></ul><ul><ul><ul><li>hypersensitivity reactions. </li></ul></ul></ul><ul><li>A characteristic triad of symptoms include: </li></ul><ul><ul><li>fever, </li></ul></ul><ul><ul><li>headache and </li></ul></ul><ul><ul><li>rash (no rash with Q fever). </li></ul></ul>
  14. 14. Diagnosis. <ul><li>Clinical: </li></ul><ul><li>These diseases present as: </li></ul><ul><ul><li>febrile illnesses after exposure to arthropods or animal hosts or aerosols ( endemic areas). </li></ul></ul><ul><ul><li>High mortality from Spotted fever (delayed diagnosis). </li></ul></ul><ul><li>The spread of the rash ( characteristic): </li></ul><ul><ul><li>spread from the trunk to the extremities (centrifugal)- typical for typhus ; </li></ul></ul><ul><ul><li>spread from the extremities to the trunk (centripetal) - typical for spotted fever . </li></ul></ul>
  15. 15. Diagnosis… <ul><li>Laboratory: </li></ul><ul><li>Macchiavello stain: </li></ul><ul><ul><li>- organisms bright red V blue background. </li></ul></ul><ul><li>Castaneda stain: </li></ul><ul><ul><li>- blue organisms V red background. </li></ul></ul><ul><li>Giemsa stain: </li></ul><ul><ul><li>- bluish purple organisms. </li></ul></ul><ul><li>4. Use of immunofluorescent antibodies: </li></ul><ul><li>NB: The organism can be inoculated into tissue culture and grown over 4-7 days (very hazardous to personnel). </li></ul>
  16. 16. Diagnosis… <ul><li>Confirmative diagnosis: </li></ul><ul><li>Serological reaction:(Weil-Felix test): </li></ul><ul><ul><li>The production of serum antibody reactive against Proteus OX19, OX2 or OXK antigens is determined </li></ul></ul><ul><li>Embryonated eggs. </li></ul><ul><ul><li>(Q- Fever) </li></ul></ul><ul><li>Cell cultures. </li></ul>
  17. 17. Important Rickettsial diseases of animals <ul><li>Heartwater: </li></ul><ul><li>Tropical canine Pancytopenia. </li></ul><ul><li>Equine and Canine Ehrlichiosis. </li></ul><ul><li>Q- Fever </li></ul><ul><li>Potomac horse Fever. </li></ul><ul><li>Salmon poisoning. </li></ul>
  18. 18. Rickettsia of Public health significance <ul><li>Tick-borne:- </li></ul><ul><li>Rocky mountain spotted fever ( R.rickettsii) </li></ul><ul><ul><li>Reservoir (Dog, rodents) </li></ul></ul><ul><li>Q-Fever ( C. burnetii) </li></ul><ul><ul><li>Reservoir ( cattle, shoat) </li></ul></ul><ul><li>Spotted Fever ( R.rhipicephali ) </li></ul><ul><ul><li>Reservoir (dogs) </li></ul></ul><ul><li>Ehrlichiosis ( E.canis ) </li></ul><ul><ul><li>Reservoir (dogs) </li></ul></ul>
  19. 19. Public health… <ul><li>Louse-borne: </li></ul><ul><li>European epidemic typhus ( R.prowazekii ) </li></ul><ul><ul><li>-No animal reservoir </li></ul></ul><ul><li>Trench Fever (Bartonella) </li></ul><ul><ul><li>- No animal reservoir. </li></ul></ul><ul><li>Flea-borne: </li></ul><ul><li>Endemic murine typhus ( R.typhi ) </li></ul><ul><ul><li>-Reservoir- Wild rodents </li></ul></ul>
  20. 20. Public health…. <ul><li>2. Cat scratch fever/bacillary angiomatosis ( Bartonella henselae ) Reservoir (domestic cat) </li></ul><ul><li>Mite-borne: </li></ul><ul><li>Scrub typhus( R. tsutsugamushi ) reservoir- wild rodents. </li></ul><ul><li>Rickettsialpox ( r.akari ) reservoir House mice. </li></ul><ul><li>Fly-borne: </li></ul><ul><li>Oroyo fever/ Verruga peruana ( B. bacilliformis ) Reservoir ?? </li></ul>
  21. 21. Treatment & Control <ul><li>Chemotherapeutic: </li></ul><ul><ul><li>Tetracycline or </li></ul></ul><ul><ul><li>Chloramphenicol </li></ul></ul><ul><li>Sanitary: </li></ul><ul><ul><li>Arthropod and rodent control are possible but difficult. </li></ul></ul><ul><li>Immunological: </li></ul><ul><ul><li>No vaccines - currently available. </li></ul></ul>
  22. 22. Chlamydia General characteristics <ul><li>Species: trachomatis , psittaci </li></ul><ul><li>The Chlamydia </li></ul><ul><ul><li>Obligate intracellular parasites. </li></ul></ul><ul><li>C. trachomatis </li></ul><ul><ul><li>Trachoma, </li></ul></ul><ul><ul><li>Inclusion conjunctivitis, </li></ul></ul><ul><ul><li>Lymphogranuloma venereum (LGV) </li></ul></ul><ul><ul><li>nongonococcal urethritis (NGU). I.e, oculourogenital infections. </li></ul></ul><ul><li>C. psittaci produces systemic diseases: </li></ul><ul><ul><li>psittacosis, </li></ul></ul><ul><ul><li>ornithosis and </li></ul></ul><ul><ul><li>pneumonitis. </li></ul></ul>
  23. 23. Distinctive properties. <ul><li>Have two distinct forms:- </li></ul><ul><ul><li>Infectious elementary bodies and </li></ul></ul><ul><ul><li>Intracellular reticulate bodies. </li></ul></ul><ul><li>Elementary bodies attach and are internalized by susceptible host cells. </li></ul><ul><li>Once inside, they reorganize into a replicative form (the reticulate body) </li></ul><ul><li>Over a 24 hour period: </li></ul><ul><ul><li>Reticulate bodies divide and begin to reorganize back into elementary bodies. </li></ul></ul>
  24. 24. Distinctive properties… <ul><li>48-72 hours after infection: </li></ul><ul><ul><li>The cell is lysed and </li></ul></ul><ul><ul><li>numerous infectious elementary bodies released. </li></ul></ul><ul><li>The genome of Chlamydia is only 25% the size of E. coli ( i.e one of the smallest prokaryotes). </li></ul><ul><li>The pathogenic mechanisms employed by Chlamydia - not well understood. </li></ul>
  25. 25. Growth and multiplication.
  26. 26. Metabolism. <ul><li>No detectable flavoproteins or cytochrome. </li></ul><ul><li>Basis of obligate intracelluar parasitism </li></ul><ul><ul><li>lack of ATP-generating ability </li></ul></ul><ul><ul><li>Obtain ATP from the host cell. </li></ul></ul><ul><li>The cells can synthesize : </li></ul><ul><ul><li>DNA </li></ul></ul><ul><ul><li>RNA and </li></ul></ul><ul><ul><li>Protein. </li></ul></ul>
  27. 27. Pathogenesis. <ul><li>C. psittaci is acquired from infected birds, usually via the respiratory route. </li></ul><ul><li>C. trachomatis is spread via the fingers to the urogenital area and vis versa . </li></ul><ul><li>Trachoma: </li></ul><ul><ul><li>Infection of the epithelial cells of the conjunctiva, producing inclusion bodies. </li></ul></ul><ul><ul><li>Vascularization and clouding of cornea along with trichiasis (inward growth of eyelashes) ---- produce scarring leading to blindness. </li></ul></ul>
  28. 28. Pathogenesis…. <ul><li>Inclusion conjunctivitis </li></ul><ul><ul><li>Milder form, </li></ul></ul><ul><ul><li>Occurs in both children and adults. </li></ul></ul><ul><li>Sexually transmitted nongonococcal urethritis (NGU): </li></ul><ul><ul><li>Similar to gonorrhea </li></ul></ul><ul><ul><li>Occurs with greater frequency. </li></ul></ul><ul><li>Lymphogranuloma venereum (LGV) involving inguinal lymphadenopathy (&quot;buboes&quot;) can occur in men </li></ul>
  29. 29. Host defenses. <ul><li>Chlamydia induce interferon and are sensitive to it. </li></ul><ul><li>During infection, antibodies are synthesized but recovery is not generally protective. </li></ul>
  30. 30. Epidemiology. <ul><li>Trachoma: </li></ul><ul><ul><li>prevalent in Africa and Asia, </li></ul></ul><ul><ul><li>generally in hot and dry areas. </li></ul></ul><ul><li>The organisms are very persistent. </li></ul><ul><ul><li>Their habitat : similar to that of Neisseria and Haemophilus . </li></ul></ul><ul><li>Infection can occur via: </li></ul><ul><ul><li>swimming in unchlorinated pools, </li></ul></ul><ul><ul><li>sharing towels or </li></ul></ul><ul><ul><li>by passage through the birth canal. </li></ul></ul>
  31. 31. Diagnosis <ul><li>Clinical: </li></ul><ul><ul><li>Diagnosis of trachoma is usually good. </li></ul></ul><ul><ul><li>Genital vesicles associated with LGV are characteristic. </li></ul></ul><ul><ul><li>NGU can only be suspected in the absence of laboratory findings. </li></ul></ul><ul><li>Laboratory: </li></ul><ul><ul><li>Iodine stained specimens usually show inclusion bodies. </li></ul></ul><ul><li>Tissue culture: </li></ul><ul><ul><li>Chlamydia can be cultured in tissue culture and appropriate serological tests performed </li></ul></ul>
  32. 32. Diagnosis <ul><li>Serological diagnosis: </li></ul><ul><li>Micro-immunofluorescent tests in tears of patients with eye infections for presence of anti-chlamydia Ab. </li></ul><ul><li>Delayed –type skin rexn (hypersensitivity Type IV) (Frei-test) </li></ul><ul><li>Rising titer of Ab V chlamydial family Ag in lung infections. </li></ul>
  33. 33. Treatment and Control. <ul><li>Chlamydia exhibit low pathogenicity in a compromised host. </li></ul><ul><li>Chemotherapeutic: </li></ul><ul><ul><li>Tetracycline or erythromycin are drugs of choice. </li></ul></ul><ul><li>Sanitary: </li></ul><ul><ul><li>Good hygiene, </li></ul></ul><ul><ul><li>Treatment of sexual partners and </li></ul></ul><ul><ul><li>Quarantine of birds all reduce the incidence. </li></ul></ul>
  34. 34. Treatment and control. <ul><li>Immunological: </li></ul><ul><ul><li>No vaccine – available since specific antibodies fail to neutralize elementary bodies in vivo . </li></ul></ul><ul><li>NB: </li></ul><ul><li>Chlamydial d’ses –relatively easy to treat, but: </li></ul><ul><ul><li>1.Latency of infection </li></ul></ul><ul><ul><li>2.Susceptibility to reinfection. </li></ul></ul>
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