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Created 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
===''[[Chlamydophila psittaci]]''===
===''Chlamydophila abortus''===
*Ovine enzootic abortion
*Especially in intensive systems
*Ewe lambs may acquire infection at birth and abort in their first pregnancy
*Pathogenesis:
**Infection via ingestion or inhalation causes a bacteraemia
**Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
**Necrosis of cotyledons and oedema of adjacent tissue, as well as dirty pink uterine discharge
**Aborted lambs well preserved
**Large numbers of chlamydiae shed in placenta and uterine discharges; survive in environment for several days
**Abortion rates may reach 30% in susceptible flock
**Ewes infected late in pregnancy may not abort, but may abort during the next pregnancy
**No other clinical signs in aborting ewes
**Fertility not impaired
*Transmission:
**Survival of elementary bodies in faeces and wild birds are a source of infection from one lambing season to the next
**Ewes may be carriers for several years
**Venereal transmission from infected rams
**Some immunity develops after infection, protecting ewes from subsequent disease
*Vaccination:
**Live attenuated vaccines prior to breeding or inactivated vaccines during pregnancy
**Vaccines prevent infection but will not clear infection from persistently-infected animals
**Vaccination of ewe lambs prior to breeding
*Treatment: long-acting oxytetracyclines during an outbreak to protect in-contact pregnant ewes
*Control: isolate aborted ewes; destroy placentas, thorough cleaning
*Also abortion in cattle, goats and pigs
*Serious infection in pregnant women
===''Chlamydophila felis''===
*Host adapted species in cats
*[[Respiratory Bacterial Infections - Pathology#Feline Chlamydiosis|Feline chlamydiosis]]
*Feline conjunctivitis, rhinitis and rarely interstitial pneumonia
*Epidemiology
**Up to 10% cats infected
**Infection via contact with conjunctival or nasal secretions
**Infection may persist with prolonged shedding and clinical relapses
**Stress of parturition and lactation may cause shedding of organisms leading to transmission to offspring
*Clinical signs:
**Incubation period 5 days
**Conjunctival congestion, clear ocular discharge, blepharospasm
**May have sneezing and nasal discharge
**Resolves within a few weeks, or causes persistent infection
*Diagnosis:
**Intracytoplasmic inclusions in stained conjunctival smears
**Antigen detection in ocular/nasal secretions - ELISA, PCR, Kosters, fluorescent antibody test
*Modified live vaccines reduce clinical signs but do not prevent infection or shedding
===''Chlamydophila pecorum''===
*Common inapparent intestinal infection of cattle
*Conjunctivitis and arthritis
*Sporadic bovine encephalomyelitis:
**Usually in cattle under 3 years
**Fever, incoordination, depression, excessive salivation, diarrhoea
**Recumbency and opisthotonos before death
**Up to 50% mortality
**Vacular damage in brain
**Serofibrinious peritonitis
**Treat with high doses tetracyclines and tylosin
===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]]
[[Category:Bacteria]]
*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
===''[[Chlamydophila psittaci]]''===
===''Chlamydophila abortus''===
*Ovine enzootic abortion
*Especially in intensive systems
*Ewe lambs may acquire infection at birth and abort in their first pregnancy
*Pathogenesis:
**Infection via ingestion or inhalation causes a bacteraemia
**Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
**Necrosis of cotyledons and oedema of adjacent tissue, as well as dirty pink uterine discharge
**Aborted lambs well preserved
**Large numbers of chlamydiae shed in placenta and uterine discharges; survive in environment for several days
**Abortion rates may reach 30% in susceptible flock
**Ewes infected late in pregnancy may not abort, but may abort during the next pregnancy
**No other clinical signs in aborting ewes
**Fertility not impaired
*Transmission:
**Survival of elementary bodies in faeces and wild birds are a source of infection from one lambing season to the next
**Ewes may be carriers for several years
**Venereal transmission from infected rams
**Some immunity develops after infection, protecting ewes from subsequent disease
*Vaccination:
**Live attenuated vaccines prior to breeding or inactivated vaccines during pregnancy
**Vaccines prevent infection but will not clear infection from persistently-infected animals
**Vaccination of ewe lambs prior to breeding
*Treatment: long-acting oxytetracyclines during an outbreak to protect in-contact pregnant ewes
*Control: isolate aborted ewes; destroy placentas, thorough cleaning
*Also abortion in cattle, goats and pigs
*Serious infection in pregnant women
===''Chlamydophila felis''===
*Host adapted species in cats
*[[Respiratory Bacterial Infections - Pathology#Feline Chlamydiosis|Feline chlamydiosis]]
*Feline conjunctivitis, rhinitis and rarely interstitial pneumonia
*Epidemiology
**Up to 10% cats infected
**Infection via contact with conjunctival or nasal secretions
**Infection may persist with prolonged shedding and clinical relapses
**Stress of parturition and lactation may cause shedding of organisms leading to transmission to offspring
*Clinical signs:
**Incubation period 5 days
**Conjunctival congestion, clear ocular discharge, blepharospasm
**May have sneezing and nasal discharge
**Resolves within a few weeks, or causes persistent infection
*Diagnosis:
**Intracytoplasmic inclusions in stained conjunctival smears
**Antigen detection in ocular/nasal secretions - ELISA, PCR, Kosters, fluorescent antibody test
*Modified live vaccines reduce clinical signs but do not prevent infection or shedding
===''Chlamydophila pecorum''===
*Common inapparent intestinal infection of cattle
*Conjunctivitis and arthritis
*Sporadic bovine encephalomyelitis:
**Usually in cattle under 3 years
**Fever, incoordination, depression, excessive salivation, diarrhoea
**Recumbency and opisthotonos before death
**Up to 50% mortality
**Vacular damage in brain
**Serofibrinious peritonitis
**Treat with high doses tetracyclines and tylosin
===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]]
[[Category:Bacteria]]