Streptococcus

Necrotising fasciitis

Flesh-eating disease caused by bacteria such as Strep. pyogenes, characterised by - infections of the deep layers of skin and subcutaneous tissue - bateria penetrate the skin and develop in lesions causing tissue necrosis - most common in immunocompromised, older and younger patients and in relation to chickenpox

Infections of the upper respirator tract are often caused by GAS bacteria. What is meant by GAS?

Group A Streptococci

Which group of bacteria is the causative agent of "Strep Throat"?

Group A Streptococci, such as Streptococcus pyogenes

Activate 1 in 5 T Cells (normal Ag 1:10,000) and infuse a massive release of cytokines & an inappropriate immune response

Superantigens, such as Toxic Shock Syndrome Toxin 1 (TSST-1)

A sore throat can by caused by a virus or a bacteria. In %, what is the colonisation rate for the two different causative agents, and what bacteria causes "Strep Throat" (Strep. Pharyngitis)?

- Cold virus causing sore throat - 70% - Beta-haemolytic Streptococcus pyogenes causing strep throat - 15 %

What are the symptoms of a sore throat caused by a virus? Compare these to Strep Throat (Strep. pharyngitis)

1. Absence of fever (present in Strep Throat) 2. Conjunctivitis 3. Coryza (inflammation of nasal mucous membranes) 4. Cough (uncommon in Strep Throat) 5. Diarrhoea

Early symptoms of Scarlet Fever

1. Flushed red face 2. Red rash that feels like sandpaper (typically 2 days after illness) 3. Red skin under arms (axilla), elbows, groin 4. Coated tongue (white) 5. Swollen tonsils

Skin diseased caused by Group A Streptococci

1. Impetigo 2. Cellulitis (multiplication and lateral spread of S. pyogenes in deer layer of the skin - dermis)

Late symptoms of scarlet fever

1. Red raw tongue (strawberry-like appearance) 2. Prominent papillae

Nine Diseases/infections caused by Strep. pyogenes

1. Streptococcal pharyngitis ("Strep Throat") 2. Scarlet Fever 3. Impetigo 4. Cellulitis 5. Necrotising fasciitis 6. Toxic Shock Like Syndrome (TSLS) 7. Acute streptococcal gingivitis 8. Rheumatic Fever 9. Post Streptococcal GlomeruloNephritis (PSGN)

Five symptoms of Streptococcal Pharyngitis

1. Sudden onset (1-5 days post exposure) 2. Sore throat causing pain on swallowing 3. Fever 4. Tiny red spots present on palate (hard and soft) 5. Enlarged and tender to touch anterior cervical lymph nodes

Strep. pyogenes is the causative agent of "Strep Throat" (Streptococcal Pharyngitis). What complications may follow after a Strep Throat infection?

Autoimmune complications including: 1. Acute Rheumatic Fever 2. Post Streptococcal GlomeruloNephritis (PSGN)

What causes Scarlet Fever?

Caused by pyrogenic/erythrogenic toxin - a substance/virulence factor produced by Strep. pyogenes when it is infected by a certain bacteriophage

Acute Streptococcal Gingivitis

Infection of the gingivae caused by Strep. pyogenes, characterised by - red gingivae - swollen gingivae - build up of fluid (oedema) in tissue - often follows sore throat

What is the cause of Necrotising fasciitis?

Invasive Streptococcus A strains that penetrate the mucous membrane and develop in a lesion

What is Scarlet Fever?

Scarlet Fever is a severe form of strep throat, associated with a red rash and a strawberry-like tongue

Severe form of strep throat associated with a red rash

Scarlet fever

Cellulitis

Skin infection caused by Strep. pyogenes, characterised by - areas of redness increasing in size over a couple of days - affects dermis and subcutaneous fat

Impetigo

Skin infection caused by Strep. pyogenes, characterised by - red sores, usually present on face - discharge from sores - highly contagious through contact - infection sits immediately below the skin

Streptococcus pyogenes is a bacteria that is part of the Group A Streptococci (GAS). What does this mean?

This is a serotype classification (Lancefield grouping), describing specific carbohydrates present on the bacterial cell wall (Streptococcal group A antigen)

What other part of the oropharynx may get infected through spread of Group A Streptococci?

Tonsils, leading to tonsillitis (Pharyngitis --> tonsillitis)

TSLS

Toxic Shock Like Syndrome, characterised by - disease similar to TSS, caused by Strep. pyogenes (Pyogenic exotoxins) - Complication of invasive infections - 30% mortality rate - Symptoms include hypotension and organ failure