5,582
edits
Changes
Chlamydia Species - General Characteristics (view source)
Revision as of 20:56, 5 November 2010
, 20:56, 5 November 2010Created page with "===Overview=== *Host adapted and non-host adapted species varying in virulence for different hosts *Species cause specific diseases in particular hosts *Respiratory, enteric, pl..."
===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 [[Joints Inflammatory - Pathology#In Sheep|arthritis in sheep]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
'''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
***High mortality
***Can be seen in smears of synovial fluid from swollen joints
***Oedematous and hyperaemic surrounding tissue
***Possibly due to intrauterine infection
[[Category:Chlamydophila species]]
*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 [[Joints Inflammatory - Pathology#In Sheep|arthritis in sheep]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
'''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
***High mortality
***Can be seen in smears of synovial fluid from swollen joints
***Oedematous and hyperaemic surrounding tissue
***Possibly due to intrauterine infection
[[Category:Chlamydophila species]]