Difference between revisions of "Chlamydia and Chlamydophila species"

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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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#REDIRECT[[:Category:Chlamydophila species]]
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
 
 
 
 
''Chlamydophila psittaci'' involved in [[Nasal cavity - inflammatory#In Cats|feline rhinotracheitis]] together with [[Herpesviridae|herpes virus 1]] C.psittaci more frequently infects the conjunctival epithelium -> chronic conjunctivitis, see [[Bacterial infections#Feline Chlamydiosis|feline chlamydiosis]]
 
 
 
*May cause [[Joints - inflammatory#In Sheep|arthritis in sheep]] and [[Joints - inflammatory#In Cattle|arthritis in cattle]]
 
 
 
===Overview===
 
 
 
*Host adapted and non-host adapted species varying in virulence for different hosts
 
*Species cause specific diseases in particular hosts
 
*Repsiratory, 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 ornthosis, 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''===
 
 
 
*Causes notifiable psittacosis in birds
 
 
 
 
 
===''Chlamydophila abortus''===
 
 
 
*Ovine enzootic abortion
 
*Especially in intensive systems
 
*Ewe lambs may acquire infection at birth and abort in their first pregnancy
 
*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
 
*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
 
*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
 
*Feline interstitial pneumonia and conjunctivitis
 
*Diagnosis by antigen detection in ocular/nasal secretions - ELISA, PCR, Kosters, fluorescent antibody test
 
*Vaccine
 
 
 
 
 
 
 
 
 
===Diagnosis===
 
 
 
*Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases
 
*Kosters (modified Ziehl-Neelson) 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 embyonated eggs and McCoy cells as well as animal tissues
 
*PCR to detect chlamydial DNA
 
*Serological tests: complement fixation, ELISA, indirect immunofluorescence
 

Latest revision as of 10:16, 12 May 2010