Difference between revisions of "Chlamydia Species - General Characteristics"
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| − | == | + | ===Overview=== |
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| + | *Host adapted and non-host adapted species varying in virulence for different hosts | ||
| + | *Species cause specific diseases in particular hosts | ||
| + | *Respiratory, enteric, pleural and reproductive diseases in animals and humans | ||
| + | *Conjunctivitis, arthritis, abortion, urethritis, enteritis, pneumonia, encephalomyelitis | ||
| + | *Manifestation varies from subclinical to severe systemic infections | ||
| + | *Intestinal infections often subclinical and persistent | ||
| + | *Human infections usualy acquired from infected birds, causing psittacosis or ornithosis, causing respiratory infections | ||
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| − | + | ===Characteristics=== | |
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| − | + | *Obligate intracellular bacteria | |
| − | + | *Gram negative bacteria with outer membrane, LPS, ribosomes, DNA and RNA | |
| + | *Peptidoglycan cell wall resistant to lysozyme | ||
| + | *Only grow in presence of living eukaryotic cells | ||
| + | *Unable to synthesis ATP therefore require intermediates from host cells | ||
| + | *Not stained by Gram stain | ||
| + | *Two morphological forms | ||
| + | **Elementary body, the infective extracellular form, which is small, metabolically inert and osmotically stable; surrounded by cytoplasmic membrane, outer membrane with LPS, but no peptidoglycan | ||
| + | **Retiuculate body: larger, metabolically active, osmotically fragile | ||
| + | *Elementary body survives in the environment for several days | ||
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| − | Clinical infections | + | ===Pathogenesis and pathogenicity=== |
| + | |||
| + | *Elementary body enters host epithelial cells by receptor-mediated endocytosis | ||
| + | *Transformation into larger reticulate body within endosome; known as an inclusion | ||
| + | *Reticulate body divides by binary fission to form many new chlamydia cells | ||
| + | *Reticulate bodies mature and condense to form elementary bodies | ||
| + | *Elementary bodies released from dying host cells after about 72 hours to infect other cells | ||
| + | *Persistent infections can occur if replication delayed by environmental conditions such as presence of interferon gamma | ||
| + | *Many infections subclinical due to intracellular existence of ''chlamydia'' preventing inflammatory reactions | ||
| + | *Chronic infections may fail to induce an immune response, or may repeatedly stimulate the immune system, causing a delayed hypersensitivity reaction and tissue damage | ||
| + | *Prolonged faecal shedding of organisms | ||
| + | *Clinical infections occur in non-natural host species | ||
| + | *CLinical signs depend on route of infection and degree of exposure | ||
| + | |||
| + | ===Diagnosis=== | ||
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*Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases | *Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases | ||
*Kosters (modified Ziehl-Neelsen) stain of placental smears shows small red rods | *Kosters (modified Ziehl-Neelsen) stain of placental smears shows small red rods | ||
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*Serological tests: complement fixation, ELISA, indirect immunofluorescence | *Serological tests: complement fixation, ELISA, indirect immunofluorescence | ||
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| + | *May cause [[Joints Inflammatory - Pathology#In Sheep|arthritis in sheep]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]] | ||
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| + | '''sheep''' | ||
| + | *[[:Category:Chlamydophila species|'''''Chlamydia sp.''''']] | ||
| + | **Sporadic or outbreaks of lamb polyarthritis | ||
| + | **High morbidity, low mortality | ||
| + | **Commonly together with conjunctivitis | ||
| + | **Most recover but may remain lame | ||
| + | |||
| + | |||
| + | '''cattle''' | ||
| − | + | **[[:Category:Chlamydophila species|'''''Chlamydia sp.''''']] | |
| − | *Severe disease in young calves | + | ***Severe disease in young calves |
| − | *High mortality | + | ***High mortality |
| − | *Can be seen in smears of synovial fluid from swollen joints | + | ***Can be seen in smears of synovial fluid from swollen joints |
| − | *Oedematous and hyperaemic surrounding tissue | + | ***Oedematous and hyperaemic surrounding tissue |
| − | *Possibly due to intrauterine infection | + | ***Possibly due to intrauterine infection |
[[Category:Chlamydophila species]] | [[Category:Chlamydophila species]] | ||
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Revision as of 20:56, 5 November 2010
Overview
- Host adapted and non-host adapted species varying in virulence for different hosts
- Species cause specific diseases in particular hosts
- Respiratory, enteric, pleural and reproductive diseases in animals and humans
- Conjunctivitis, arthritis, abortion, urethritis, enteritis, pneumonia, encephalomyelitis
- Manifestation varies from subclinical to severe systemic infections
- Intestinal infections often subclinical and persistent
- Human infections usualy acquired from infected birds, causing psittacosis or ornithosis, causing respiratory infections
Characteristics
- Obligate intracellular bacteria
- Gram negative bacteria with outer membrane, LPS, ribosomes, DNA and RNA
- Peptidoglycan cell wall resistant to lysozyme
- Only grow in presence of living eukaryotic cells
- Unable to synthesis ATP therefore require intermediates from host cells
- Not stained by Gram stain
- Two morphological forms
- Elementary body, the infective extracellular form, which is small, metabolically inert and osmotically stable; surrounded by cytoplasmic membrane, outer membrane with LPS, but no peptidoglycan
- Retiuculate body: larger, metabolically active, osmotically fragile
- Elementary body survives in the environment for several days
Pathogenesis and pathogenicity
- Elementary body enters host epithelial cells by receptor-mediated endocytosis
- Transformation into larger reticulate body within endosome; known as an inclusion
- Reticulate body divides by binary fission to form many new chlamydia cells
- Reticulate bodies mature and condense to form elementary bodies
- Elementary bodies released from dying host cells after about 72 hours to infect other cells
- Persistent infections can occur if replication delayed by environmental conditions such as presence of interferon gamma
- Many infections subclinical due to intracellular existence of chlamydia preventing inflammatory reactions
- Chronic infections may fail to induce an immune response, or may repeatedly stimulate the immune system, causing a delayed hypersensitivity reaction and tissue damage
- Prolonged faecal shedding of organisms
- Clinical infections occur in non-natural host species
- CLinical signs depend on route of infection and degree of exposure
Diagnosis
- Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases
- Kosters (modified Ziehl-Neelsen) stain of placental smears shows small red rods
- Blue inclusions in cytoplasm of Giemsa-stained cells
- Methylene blue stain with darkfield microscopy
- Fluorescent antibody stain
- Antigen detection kits for diagnosis from swabs
- ELISA to detect Chlamydophila LPS
- Isolation in embryonated eggs and McCoy cells as well as animal tissues
- PCR to detect chlamydial DNA
- Serological tests: complement fixation, ELISA, indirect immunofluorescence
- May cause arthritis in sheep and arthritis in cattle
sheep
- Chlamydia sp.
- Sporadic or outbreaks of lamb polyarthritis
- High morbidity, low mortality
- Commonly together with conjunctivitis
- Most recover but may remain lame
cattle
- Chlamydia sp.
- Severe disease in young calves
- High mortality
- Can be seen in smears of synovial fluid from swollen joints
- Oedematous and hyperaemic surrounding tissue
- Possibly due to intrauterine infection
- Chlamydia sp.