Chlamydia and Mycoplasma
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- Created by: fionnualamaire94
- Created on: 01-12-16 01:25
Chlamydophila
- C. pneumoniae, C. pecorum, C. psittaci, C. abortus, C. felis, C. caviae
- intracellular Gram-ve
- obligate intracellular parasites - incapable of obtaining ATP by metabolic activities
- complex life cyle - distinct infectious forms (EB) and reproductive forms [intermediate forms (IF) and reticular bodies (RB)]
- EB - outer membrane with LPS, haemaglutinin and major outer membrane protein (MOMP)
- rigid cell wall
- RNA:DNA content 1:1
- isolated organisms infectious
- adapted for extracellular survival
- RB - opposites to above, RNA:DNA content 3:1
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Pathogenesis Chlamydophila
- life cycle takes place in the endosome
- many mechanisms for avoiding immune recognition
- inhibition phagolysosomal fusion
- down-regulation of class II antigens
- inhibition of apoptosis
- proteolytic cleavage of NF-xB
- DNA, RNA and protein synthesis eventually ceases in the infected cells
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Infections Chlamydophila
- ocular
- acute or chronic
- catarrhal conjunctivitis, keratitis and superficial corneal ulceration can occur
- abortion in ruminants
- 20-50% of sheep abortions in UK due to Cp. abortus Economic costs to the farming industry
- placentitis with cotyledonary necrosis and intercotyledonary oedema
- pulmonary/respiratory chlamydiosis
- exudative and/or purulent bronchiolitis with tracheitis
- pneumonia with areas of consolidation
- male genital tract
- arthritis
- intestinal infections
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Chlamydia abortus
- endemic among ruminants - efficiently colonsie the placenta
- around day 90 of gestation, coincident with a phase of rapid fetal growth Chlamydophila produces a progressively diffuse inflammatory response - thrombotic vasculitis and tissue necrosis
- abortion, stillbirth, delivery of weak - fullterm neonates, apparently normal lambs may also be affected
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Chlamydophila felis
- part of feline upper respiratory tract infection (URI) complex
- affects nose and eyes and manifests similar symptoms
- accounts for 10-15% of all feline URI cases and often occurs with another URI
- mainly causes conjunctivitis in young kittens (5-12 weeks)
- may also lead to flu-like symptoms
- anorexia
- coughing/difficulty breathing
- fever
- pneumonia
- runny nose
- sneezing
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Avian chlamydiosis (psittacosis, ornitosis)
- pneumonia
- firbrino-necrotising serosis of body cavities and organ surfaces, hepato-splenomegaly with dilation of sinusoids and infiltration of mononuclear cells and lymphocytes can be observed
- greenish yellow gelatinous faeces
- reduced egg production
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Psittacosis
- transmission and infection - respiratory and oral
- symptoms
- variable depending on strain, age and immune status of bird and presence of concurrent infections
- usually related to respiratory and digestive system
- treatment and measures
- depends on species, age, immune status, length of illness, virulence of infecting strain - sooner treatment is sought the better the outlook
- isolate all sick, incoming new birds (30-45 days)
- test symptomatic birds, treat infected birds (doxycycline 45 days)
- clean and disinfect cages , keep feather dust circulation to a minimum, droppings from infected bird soaked with disinfectant before disposal
- contact with humans and infected birds kept to absolute minimum, monitor any flu-like symptoms in human caretakers
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Laboratory Diagnosis Chlamydophila
- specimens
- abortion - cotyledons, vaginal swabs, aborted fetus, and culture
- arthritis - synovial fluid
- conjunctivitis - conjunctival swab
- systemic infections - lung, liver, spleen, pericardium
- diagnostic methods
- staining methods
- culture - suitable transport medium, keep at 4C, cell culture - 2-3 days in absence of antibiotics that kill Chlamydia, followed by staining or IF - can be decontaminated using gentamicin, vancomycin, and nystatin
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Chlamydia - Treatment and Vaccine
- tetracycline (doxycycline) is drug of choice
- birds - can be incorporated into feed as impregnated seeds eg
- vaccine can reduce disease but often has limited efficacy in preventing infection
- Ruminant vaccines - inactivated whole cell, addition of adjuvants OR live attenuated vaccine C. abortus Enzovax, CEVAC
- Avian chlamydiosis - "no effective vaccine for avian chlamydiosis"
- Feline chlamydiosis - inactivated vaccines
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Mycoplasmatales
- Most important genera - Mycoplasma, Ureaplasma
- common to refer to all Mollicutes as mycoplasmas despite only one genus being Mycoplasma
- first recognised mycoplasmal disease was a veterinary disease - contagious bovine pleuopneumonia - Germany 1863
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Mollicutes - what are they?
- smallest free-living cells known
- morphology and size are variable
- spherical forms 300-800nm in diameter
- filamentus forms 100-300 nm x 3-150 um
- genome is 1/3 of size of bacterial
- membrane lacks peptidoglycan and is very flexible
- Gram -ve
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Mycoplasmas - reproduction and metabolism
- divide by binary fission
- genome replication > multinucleated filaments > chains of coccoid cells > fragmentation into individual cells
- mycoplasmas divide slowly - 1-6 hours
- optimal growth temp 37C
- glucose used as main source of energy
- facultative anaerobes
- arginine can be used as alternative source of energy
- require lipids and sterols for membrane synthesis
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Mycoplasmas - pathogenesis
- Attachment - mainly by anionic surface layer, some species have specialised surface structures, host cell receptors are glycoproteins, some inhibit ciliary movement or destroy cilia - helps attachment and predisposes to bacterial super-infections
- Toxins - haemolysin, proteases, nucleases, neurotoxin (M. neurolyticum)
- Complement activation - can be detrimental to bystander cells and causes inflammation via release of chemotactic fragments
- Cytokine activation - TNF, IL-6, IL-1, M.arthriditis has T-cell super antigen induced cytokine production and inflammation
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Mycoplasma - evasion of the immune response
- Decrease phagocytosis - in neutrophils and macrophages
- Decrease respiratory burst - persistance in phagocytes
- polyclonal activation of B-cells
- Antigentic variability
- Molecular mimicry
Latent infections are common - as consequence of numerous mechanisms for evading immune responses
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Pathology of mycoplasma
- Acute
- inflammation
- neutrophil infiltration
- fibrin accumulation
- generalised fibrinopurulent exudate on serosal membranes and synovial membranes
- septicaemic forms with coagulopathy, vascular thrombosis, shock mediated by cytokines
- Persistent Localised
- tissue destruction
- pockets of encapsulated pus (mastitis) usually evolving to fibrosis
- proliferative synovitis and erosive arthritis
- pleural thickening
Main forms of disease are: respiratory, articular and mastitis
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Farm Animals - mycoplasmas
- respiratory disease, mastitis, arthritis, genital disease, eye lesions
- most important - contagious bovine pleuropneumonia (CBPP), contagious agalactia (CA) and contagious caprine pleuropneumonia (CCPP) - none present in Britain
- Infections caused by M. gallisepticum in chickens, M. hyopneumoniae in pigs, and Mycoplasma bovis in cattle can result in considerable economic loss
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Birds - mycoplasma diseases
- M. gallisepticum - chronic respiratory disease in chickens, turkeys, pheasants
- coughing, nasal discharge, tracheal rales
- airsacculitis
- synusitis in turkeys, synusitis with exudate, swollen face
- M. synoviae
- synovitis, lameness, swelling of the joints and tendon sheaths
- M. meleagridis and M. iowae
- leg and spine deformities
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Pigs - mycoplasma diseases
- M. hypopneumoniae (enzoonotic pneumonia)
- high morbidity but low mortality, retarded growth
- chronic non productive cough
- M. hyorhinis
- systemic infection in pigs between 3 and 10 weeks old. Fever, reduced appetite, followed by swelling of the joints and lameness. polyserositis involving pleura, peritoneum, pericardium and synovial membranes
- M. hyosynoviae
- synovitis, arthritis, lameness
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Cattle - mycoplasma disease
- M. mycoides - cause of contagious bovine pleuroplenumonia
- subclinical, chronic and acute/fatal infections
- respiratory distress, coughing, nasal discharge, arthritis can occur in young animals
- M. bovis - also M. californicum, M. canadense, M. bovigenitalium
- drop in milk production, thickening of the milk with watery secretion sometimes progressing to purulent
- tissue destruction with swelling and fibrosis of the mammary gland is observed
- M. bovis and M. dispar
- pneumonia with brinchiolitis
- M. bovigenitalium and Ureaplasma diversum
- seminal vesiculitis in bulls, vulvitis, endometritis and abortion in cattle
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Mycoplasma - diagnosis
- clinical symptoms - pneumonia, arthritis, mastitis etc
- laboratory diagnosis
- main tests
- PCR tests
- cultivation
- serology - western blot/ELISA
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Mycoplasma - control
- antibiotic treatment
- tetracyclines, tylosin, erythromycin, lincomycin, spectinomycin
- resistance can develop - infections are difficult to eliminate and a post-treatment carrier state often develops
- CBPP and CCPP - ususally controlled by culling infected herds
- poultry - isolation or culling infected animals followed by strict containment measures and seological monitoring is an effective measure for control
- similar measures control M. hypopneumoniae in pig herds
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