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Chlamydia and Chlamydophila species (view source)
Revision as of 10:16, 12 May 2010
, 10:16, 12 May 2010Redirected page to Category:Chlamydophila species
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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
−*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 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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−===Pathogenesis and pathogenicity===
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−*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
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−===''Chlamydophila psittaci''===
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−*Causes notifiable psittacosis in birds
−*Epidemiology:
−**Many wild and domestic birds susceptible
−**Organisms present in respiratory secretions and faeces of infected birds
−**Infection via inhalation or ingestion
−**Subclinical infection common
−**Intermittent shedding for prolonged periods
−**Stress precipitates disease outbreaks
−*Clinical signs:
−**Generalised infection affecting intestinal and respiratory tracts
−**Up to 10 day incubation period
−**Loss of condtion, oculonasal discahrge, diarrhoea and respiratory distress depending on strain
−**Hepatomegaly, airsacculitis and peritonitis
−*Diagnosis: stained smears, immunohistochemistry, ELISA, PCR, isolation, antibody detection by ELISA and complement fixation
−*Treatment: tetracyclines for several weeks
−*Control: quaranteen imported birds and give tetracyclines; good husbandry
−*Involved in [[Nasal Cavity Inflammatory - Pathology#In Cats|feline rhinotracheitis]] together with [[Herpesviridae|herpes virus 1]]
−*Zoonotic by aerosol infection - can cause systemic disease with pneumonia, meningitis or meningoencephalitis
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−===''Chlamydophila abortus''===
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−*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
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−===''Chlamydophila felis''===
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−*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
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−===''Chlamydophila pecorum''===
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−*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
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−===Diagnosis===
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−*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
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−*May cause [[Joints Inflammatory - Pathology#In Sheep|arthritis in sheep]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
#REDIRECT[[:Category:Chlamydophila species]]
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