Spirochaetes

Question 1

Features of spirochaetes

Answer 1

Very unusual bacteria:
Gram-negative
Very thin- viewed by dark-field microscopy or EM
-Spiral shape
Varied genome size
Many plasmids (large)
Virulence factors poorly understood
Unique method of motility via internal flagella
Anaerobic
Slow growing

Question 2

How to diagnose spirochaetes via a lab?

Answer 2

Relies on serological or immunofluoresence tests

Question 3

Spirochaete taxonomy?

Answer 3

Recognised by cell shape

Identification by sequence analysis of 16s rRNA gene

Question 4

What makes spirochaetes different?

Answer 4

Internal flagella = axial filaments

Question 5

What occurs when deletion of flagella assembly genes occurs?

Answer 5

Aflagellate non-motile strains
No longer corkscrew like = straight rod shaped cells
Occurs for Treponema denticola and Borrelia burgdoferei

Question 6

How to spirochaetes swim?

Answer 6

Counter-rotation of the internal flagella filament bundles = rotation of cell body = burrowing motility of spirochaetes

Question 7

What is located on the spirochaete cell surface?

Answer 7

Cell wall components = can modulate immune response, known as major sheath proteins
No LPS - glycolipids

Question 8

What diseases can spirochaetes cause?

Answer 8

Leptospira = Weils disease
Borrelia = Lyme disease, relapsing fever
Treponema = ANUG, periodontitis

Question 9

Zoonotic infections examples?

What do zoonotic infecs have?

Answer 9

Lyme and Weil’s disease

Have an animal reservoir of infec that can under certain circumstances infect humans via a zoonotic vector

Question 10

Lyme disease cause?

Answer 10

Caused by Borrelia burgdoferi and related sub-species

Question 11

Features of lyme disease?

Answer 11

Most common zoonootic bacterial infec in europe

Nutritionally fastidious anaerobe

Question 12

Zoonotic reservoir?

Answer 12

Transmission via lxodes spp. ticks
Ectoparasites of many vertebrate species; rodents, deer, birds
3 life-cycle stages;
- Fed once in each stage; 3-5 days per feed
Bac live and multiply in midgut of ticks
Transmitted via saliva after biting humans

Question 13

Stages of infec - acute of lyme disease?

Answer 13

Flu-like symptoms
Localised rash
Bulls-eye rash

Question 14

Stages of infec - later of lyme disease?

Answer 14

Seen from 1 week to 2 years post-infection:

• Neurologic: Meningitis, encephalitis, peripheral neuropathy, cranial-nerve (facial) palsies, vision impairment (chronic)
• Cardiac: myocarditis, blockages
• Athralgia and arthiritis- may persist for months or years - often debilitating- possible autoimmune component – reactivity to surface proteins (OspA)

Question 15

What causes the later symptoms?

Answer 15

When bac enter sites other than the bloodstream - neurons, joints

Question 16

Borrelia burgdoferi feautres?

Answer 16

Motility considered a major virulence factor
Invades epithelial cells
Capable of invading many tissue types
No LPS, but numerous Outer membrane lipoproteins OspA-D, expressed at different points in infection cycle. Vls proteins- variable suface proteins- antigenic shift
DbpA- Decorin binding protein, host mimicry?
Copes with low-iron levels by using Manganese instead of iron as an enzyme co-factor

Question 17

How to prevent lyme disease?

Answer 17

Antibiotics - doxycycline - chronic infecs hard to treat since bac metabolically inert and resides in sites refractory to treatment

Vaccine - to OspA only partly effective (OspA expressed in tick, not humans)

Prevention - avoid endemic areas, clothing, DEEP based repellants

Question 18

Relapsing fever?

Answer 18

Borrelia recurrentis
Transmitted via ticks and human body louse
Repeated febrile illness
Initial infection cleared, but antigenic variation by the bacterium starts a new set of symptoms
3-10 episodes
Can infect liver/ spleen

Question 19

How could it relapse?

Answer 19

Antigenic variation- surface protein OspC multiple copies- expressed variably in recurring infecitons

Question 20

How to prevent and control relapse?

Answer 20

CDC; check for mice/rodents

Question 21

Leptospirosis and Weils disease?

Answer 21

Caused by Leptospira interrogans
- Leptos (Gr) – ununusually thin spira (la) -   colied, spiral
Two terminal Periplasmic flagella
Present in stagnant water and rivers
Infects many mammals
Dogs and Rats most important zoonotic reservoir (urine)
Enter via broken skin
40- 60 cases/ year in England
Outbreaks in walkers, triathlon runners!

Question 22

Symptoms of leptospirosis (weils disease)?

Answer 22

1-2 week incubation in blood
Leptospirosis: Febrile, flu-like illness with muscle pain, reddening of eyes, and other symptoms such as diarhoea and in some cases meningitis and Hemorrhage in Aqueous humour of eye and CSF

Question 23

What does weil’s disease cause?

Answer 23

Kidney failure, jaundice and liver failure

Most symptoms due to BV damage

Question 24

How to prevent and treat leptospirosis?

Answer 24

Rodent controlled
Doxycline
Avoid swimming in infected rivers

Question 25

What spirohoates cause issues in the mouth? Treatment?

Answer 25

Treponema vincentii = acute necrotising ulcerative gingivitis
Treatment = metronidazole or H202 washes

Question 26

What organisms are commonly found in periodontal cases?

Answer 26

Treponema denticola
Red complex organisms - (Porphyromonas gingivalis
Tannerella forsythia, Treponema denticola)

Question 27

Treponema denticola: virulence?

Answer 27

Adherence to basement membrane proteins via 53 Kda Msp : fibronectin, laminin, fibrinogen, type IV collagen and gelatin

Proteases: in-keeping with other periodontal pathogens
CTLP- Chymotrypsin like Protease (Dentilisin), surface exposed in outer membrane: Cleaves transferrin, fibrinogen, fibronectin, IgA, IgG, gelatin
Sialidases:- cleaves surface sialic acid from human cells/ saliva- mutant reduced infection in mice
Motility: tissue invasion and disease progression
Co-adherence with other oral bacteria in mixed biofilm also important (i.e. Pg, Tf, and Fuso’s)

Question 28

Syphilis: Treponema pallidum treatment?

Answer 28

Treatment with mercury

Question 29

Name other treponemal diseases and their features

Answer 29

Yaws: T. pertenue 
- early skin lesions that clear
- later destructive lymph
- south america and central africa
Pinta: T. carateum 
- again early skin lesions
- these progress to chronic disfiguring lesions over time
- south and central america

Question 30

How are treponemal diseases spread?

Answer 30

Skin to skin transmission

Question 31

How to treat treponemal diseases?

Answer 31

Treatable with penicillin