4 pathogenic spirochaete genera
- Leptospira
- Treponema
- Borrelia
- Brachyspira
Spriochaetaceae
-features
- unusual, elegant morphology (long and slender, spiral morphology)
- Gram neg, and stain poorly
- characterised by presence or periplasmic flagella which confer motility (located under outer envelope)
- one set anchored at each cell end, running back down the cell length, overlapping w/ other set towards the centre of the spirochaetal cell
Genus: Leptospira
- features
- what inactivated by
- Worldwide distribution
- Economically important disease
- major zoonosis
- 20 serogroups + > 200 named serovars (still being discovered)
- very difficult & slow to grow (+ dangerous)
- LPS activates TLR2 (toll like receptor) not TLR4 (different immune response)
- easily inactivated by heat, require moisture for survival
- survives 1 wk in pig urine
Pathogenesis of Leptospirosis
- how they can be carried
- penetration
- 4 generalised effects
- Obligate parasites + enviro species
- long-term carriage in kidney tubules
- Passed in urine, contaminating slurry and water systems
- can penetrate conjuctive, or enter skin via abrasions
- bacteraemia develops then localises in kidney tubules (causes kidney failure)
- can get generalised effects such as hepatitis, abortions, haemolysis and bleeding
Leptospira
-maintenance host & Accidental host
- Maintenance host: acts as a reservoir
- host adapted serovars generally cause mild disease in host species, w/ long term carriage
- rats
- Accidental host: not essential for survival for survival of serovar
- acute and often severe disease
- generally need higher dose to become infected
- can occ. infect humans
Leptospirosis
- Public health
- Diagnosis (4)
-An emerging disease in outdoor humans
-v. severe outbreaks in China, central America
Diagnosis;
-Microscopic examination (plasma, urine)
-Culture
-Animal inoculation
-Serological examination
Control and Prevention (Leptospirosis) (4)
- Control wild animal populations
- Decreased prevalence of infection in maintenance hosts (wild animals)
- Improve hygiene standards
- Immunise and treat accidental hosts
Treponema
- features
- 2 species and what they cause
- Slender spiral shaped filaments
- Motile-corkscrew action
- Do not stain easily
- Difficult to culture
- 2 species: T. pallidum (Syphilis) & T. pertenue (yaws)
T. pallidum
-primary, secondary and tertiary signs
- The agent of human syphilis (never been cultured)
- veneral disease (sexual contact)
- Primary lesions on genitalia = chancre
- secondary: later lesions elsewhere (e.e.g skin - is infectious)
- tertiary: neurological signs (brain)
- chronic disease, diagnosed by serology (can be cured by antibiotic treatment)
Diagnosis of T. pallidum
- Microscopic examination
- Serology for syphilis
T. pertenue
- what it causes
- typical signs
- infects humans only
- “yaws”
- tropical ulcers, skin, bone joints
- palms of hands and soles of feet
- heals after 3-6 months but may get deformities and scars
Borrelia -features
-mode of transmission
- Spiral shaped
- motile
- Gram negative
- 36 species
- 12 cause lyme disease/borreliosis
- all arthropod-borne bacteraemias, relapsing fever
- spread by ticks
2 species of Borrelia
- B. recurrentis (relapsing fever)
- B. burgdorferi (Lyme disease)
*major emerging zoonosis
Borr. recurrentis
- what it causes
- what transmits it
- special feature of it
Borr. hermsii
- what it causes
- reservoirs
- more or less fatal
-Agent of epidemic relapsing fever in humans
-Louse-borne
-obligate pathogen
-grows in gut (of louse)
*undergoes antigenic change, leading to recurrence
-severe generalised disease
-present in Africa/South America
Borr. hermsii
-endemic recurrent fever
-reservoirs in small mammals, rodents
-transmitted by soft body ticks
-again, severe generalised disease but more fatal
Borr. burgdorferi
- what it causes
- mode of transmission
- how it evades immune attack
- features of disease
- Agents of lyme disease in humans and dogs
- transmitted by ticks
- microaerophilic and slow growin
- varies surface proteins to avoid immune attack
- localised lesions around the bite; fever, enlarged lymph nodes and sometimes chronic reactive arthritis, neurological complications, renal failure
*not yet in Australia
Borr. burgdorferi
- unusual membrane
- what it doesn’t need
- how it moves
- Has unusual membrane that contains glycolipid (not LPS)
- does not need iron to grow, little oxygen
- divides every 12-18 hours (v. slow)
- can move in corkscrew fashion through CT
Diagnosis of Borrelia (2 methods)
Control
-Microscpic examination in blood
-serology
Control;
-vaccines: recombinant surface proteins for Lyme disease - but no longer commercially available
-not routinely used in Australia
Brachyspira
- Resistence
- pathogenic status?
- features
- has antibiotic resistence due to high use of antibiotics
- emerging pathogens due to antibiotic (growth promoters) in pigs
- Anaerobic intestinal spirochaetes
- slow growing
- colonise large intestine
- Previously weak, but ow strong haemolysis
Other types of Brachyspira
- B. hyodysenteriae: agent of swine dysentry
- B. pilosicoli: weakly haemolytic
- B. murdochii: mildly pathogenic and/or commensals
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Bacteria Structure & Function22
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Bacterial Metabolism & Growth18
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Disinfection, Sterilisation & Antibiotics46
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Symbionts and Pathogens25
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Bacterial Identification, growth, gene exchange & Isolation25
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Bacterial Pathogenesis and Transmission21
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Enterobacteriacaea18
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Purulent and bacteraemic infections23
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Toxaemic and Respiratory Tract Infections18
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Granulomatous and Reproductive Tract Infections20
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Spirochaetaceae19
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Mycoplasmas11
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Rickettsias & Chlamydias28
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Opportunistic Pathogen: Pseudomonas aeruginosa14
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Antimicrobial Resistance14
