Spirochetes Flashcards

1
Q

Distinctive features

Lab diagnosis depends on

A
Spiral shaped
Normal gram -ve rod 
Many plasmids 
Internal flagella 
Varied genome size 

Anaerobic
Slow growing
fastidious
Some uncultivable

Antibody tests e.g gluttination or serological

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2
Q

Taxonomy

How are they recognised

How are they identified

A
3 main disease causing types 
- leptospira
- borrelia
- treponema 
Recognised by cell shape
Identified by sequence analysis of 16s rRNA gene
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3
Q

Species identification by…

A

16s rRNA sequencing
16s rDNA gene is ell conserved and acts as molecular clock
Sequence it to speciate bacteria

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4
Q

Link between cell structure and motility

Deletion of flagella gene results in

A

Spiral shape due to internal flagella – AXIAL FILAMENTS
Cell shape defined by combination of peptidoglycan layer and bacterial cytoskeleton

Aflagellate non-motile strains which become straight rod shaped cells e.g treponema denticola

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5
Q

How do they swim

A

Counter rotation of internal flagella bundles results in rotation of cell body
Rotation = burrowing motility of spirochaetes e.g into tissue

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6
Q

Spirochaete cell surface
Cell wall

LPS

A

Cell wall components can modulate immune response –> MAJOR SHEATH PROTEINS

No LPS like other gram -ve bacteria

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7
Q

Spirochetes disease

Leptospira

Borrelia

Treponema

A

Weils disease, Leptospirosis

Lyme disease, relapsing fever

Syphilis, ANUG, periodontitis

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8
Q

Zoonotic infections

A

Lyme disease and Weil’s disease - animal involvement

Animal reservoir of infection which affects humans via vector

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9
Q

Lyme disease

Cause

Common where

Viewed by

What kind of microbe

A

Borrelia burgdoferi

Small spirochete only viewed by EM and Dark-field

Anaerobe

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10
Q

Zoonotic reservoir

Life cycle

A

Transmission via ticks
Arthropods in group arachnid
Ectoparasites of many vertebrate species

3 stages
Feed once in each
Bacteria live and multiply in midgut of ticks and are transmitted via saliva after biting humans

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11
Q

Stages of infection with BB - ACUTE

Can lead to

Bacteria hides in places like

A
Flu like symptoms often seen 
localised rash 
Erythema migrans
Bulls-eye rash 
Other lessons at sites distal to innoculation

Arthritis
Cardiac symptoms
Palsy on face

Joints

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12
Q

Stages of infection of BB - chronic

Caused when

A

Seen 1 week-2 years post-infection
Neurological - meningitis, encephalitis, peripheral neuropath, CN palsies, vision impairment
Cardiac - myocarditis, blockages
Arthralgia and arthritis - months or years - often debilitating - due to reactivity to surface proteins - autoimmune

When bacteria enters sites other than bloodstream e.g neurons and joints

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13
Q

Borrelia burgdoferi

Mechanisms of infection

A

Motility
Invades epithelial cells
Invades many tissue types
No LPS but has lipoproteins called OSPA-D - harder to detect –> ANTIGENIC SHIFT
DbpA - mimics man protein
Copes with low iron levels by using manganese

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14
Q

Prevention and treatment

Vaccine

Preventive measures

A

Antibiotics eg doxycycline
Chronic infections harder to treat

Partially effective - target not expressed in humans
some side effects - may stimulate auto immune disease

Avoid endemic areas
Clothing, repellents

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15
Q

Relapsing fever

Caused by

Transmitted by

Mechanism
Can infect?

A

Borrelia recurrentis

Transmitted via ticks and human body louse

Febrile illness

Initial infection cleared but antigenic shift stimulates new set of symptoms
3-10 episodes
Can infect liver/spleen

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16
Q

Leptospirosis and Weil’s disease

Caused by

Characterics

Present in

Infects what

Enter via

A

Leptospira interrogans

Terminal periplasmic flagella

Present in stagnant water and rivers

Infects mammals

Dogs and rats common zoonotic reservoir

Enter via broken skin on hands and feet

17
Q

Leptospirosis and Weil’s disease - symptoms

Prevention and control

A

1-2 week incubation in blood

Febrile, flu like, muscle pain, vitreous humour haemorrhage, diarrhoea, meningitis

> >

Kidney failure, jaundice and liver failure

Rodent control
Doxycycline
Avoid swimming in infected rivers

18
Q

Dental relevance

ANUG - caused by, treated with

Treponema denticola

with

A

Complex of organisms involving Treponema vincentii (and prevotella, streptococcus)
Metronidazole and H2O2 washes

Red complex, anaerobic, most commonly found in periodontal disease

Porphyromonas gingivalis
Tannerella forsythia
Treponema denticola

19
Q

Treponema denticola

Virulence

Contains

A

Adheres to basement membrane proteins
Asaccharalytic

Proteases - use components for food

Sialidases

Motility - tissue invasion

Co-adherence - form biofilm

20
Q

Syphilis - caused by

A

Treponema pallidum

21
Q

Other treponemal diseases

A

Yaws - skin lesions

Pinta - skin lesions - skin to skin transmission