Infectious Disease -- Streptococci Review Flashcards by Bryan Edwards

Streptococcal patterns of disease?

Spreading of suppurative skin infections

Post-streptococcal hypersensitivity disease

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Manifestations of Streptococcal spreading suppurative skin infections

Cullulitis
Erisypelas
GABHS
Impetigo

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Manifestations of post-Streptococcal hypersensitivity disease?

Rheumatic Fever

Immune Complex Glomerulonephritis

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Three groups of Streptococcal infections

Group A
Group B
Viridans

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Whats Group A Strep all about…

S. pyogenes
beta hemolytic
Pharyngitis/post streptococcal disease

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Whats Group B Strep all about…

Perinatal Sepsis/Newborns, UTIs

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What is Strep viridans all about…

Grouped as alpha hemolytic

Major cause of subacute bacterial endocarditis

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Why care about strep mutans?

Major cause of dental caries

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Streptococcal virulence factors?

Call wall polysac./capsules (M Proteins)
Enzymes – streptokinase, streptolysin O, S
Erythrogenic toxins

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Purpose of Cell Wall polysaccharides/capsules?

Prevention of phagocytosis

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Significance of Streptococcal enzymes (streptokinase, streptolysin)

Contribute to ability to spread through tissues

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What do Streptococcal erythrogenic toxins cause

Skin Rash

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Initial presentations of Group A streptococcal disease

Acute Pharyngitis/URT

Scarlet Fever

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Symptoms of Group A Streptococcal Acute Pharyngitis?

Reddness, Edema, Pain
Fever, Chills
Punctate abscess in tonsillar crypts
Peritonsillar, retropharyngeal abscess formation

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What is Group A Streptococcal Scarlet Fever

Severe, prolonged group A pharyngitis

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Symptoms of Group A Scarlet Fever

Febrile Exanthematous Disorder
Erythrogenic toxin (causes violaceous red rash on trunk)
Strawberry tongue
Desquamination of Skin

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What does Febrile Exanthematous Disorder look like

Unraised blotches all over body

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Describe presentation of post-streptococcal glomerulonephritis

1-2 weeks after strep throat
Immune-complex mediated
Can cause renal failure

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Describe presentation of rheumatic fever

Weeks-months+ after infection
Fever, Joint Disease, Myocardial/Valvular disease
Eventually, long standing damage to mitral/aortic valves

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How does acute rheumatic fever happen?

Autoimmune reaction that is caused by a cross reaction with M antigens.
Strength of response corresponds to streptolysin O titers in the blood
Abs can cause damage/thickening of valves

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What to Streptococcal skin infections look like?

Cellulitis, pyoderma

Extensive spreading reddness, swelling, pain

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Rare complications of Streptococcal skin infection

Abscess, Pustule

Necrotizing fasciitis

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Describe impetigo

Contagious skin infection in kids involving horny (superficial) skin layers

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Who gets erysipelas?

Middle aged persons, esp in the Tropics

Describe the presentation of an erysipelas patient

Superficial infection Breaks, erythema seeps through and crusts No suppuration

Presentation of necrotizing fasciitis

Soft tissue gangrene | Fournier's gangrene

necrotizing fasciitis usually only happens in which patients

Diabetics, pre existing immunodeficiency

Describe what actually happens to a person's body in necrotizing fasciitis.

The streptococcal infection kills off blood vessels in the tissues, allowing a hypoxic region to develop. At this point , the wound is taken over by anerobes that have to get cut out.

Subacute bacterial endocarditis is caused by...

S. viridans transient bacteremia following dental work why heart damages patients have prophylactic antibiotics

Puerperal sepsis is caused by

Group B

How to diagnose Strep Throat

Rapid Strep Test -- Group A Strep Carbohydrate antigen | Confirm culture in 12-48 hours

How to diagnose Rheumatic Fever

Anti-streptolysin O Ab | Even through cross reacting Abs are actually specific for M protein

Streptococcal infections are grouped by _____ antigens

Lancefield

Streptococcal infections are typed by ______

ability to hemolyse blood agar

Common symptoms of Streptococcal skin infection

Cellulitis, Impetigo, Erysipelas

Members and important details for Streptococcal Group A.

GABHS S. pyogenes Pharyngitis/post-streptococcal disease

Members and important details for Streptococcal Group B

S. agalactiae Perinatal Sepsis/Newborns UTIs

Members and important details for Streptococcal Group D

Anaerobic S. faecalis and enterococcus

Members and important details for Strep Viridans

Alpha hemolytic Major cause of subacure bacterial endocarditis Access to blood stream from mouth colonization with dental work

Streptococcal Virulence Factors

1. Cell wall PS/Capsules (M Proteins) 2. Streptokinase, Streptolysin O, S 3. Erythrogenic Toxin

Antibodies to Group ____ Streptococcal antigens may cross react with human tissue and cause rheumatic fever

Contagious Bacterial Streptococcal pharyngitis is caused by...

GABHS | Pyogenes

Acute Rheumatic Fever is caused by antibodies to ___, which correlates with ______ titers in the blood

M proteins | Anti-streptolysin O

Causes of Post-streptococcal glomerulonephritis | Why?

Impetigo, Severe Pharyngitis These are the forms of Streptococcal infection that last for long enough to still have antigen present when the antibodies specific to them are generated.

Name the scrotal/perineal form of necrotizing fasciitis

Fournier Gangrene

Two groups more likely to develop Necrotizing fasciitis

Immunodeficient | Diabetics

What to look for in an X ray of a patient with a subcutaneous strep infection with necrosis that is overtaken by anerobes

Gas formation

Subacute bacterial endocarditis

Assoc. with S. viridans (transient following dental work) | left sided valvular endocarditis

Pathologic features of skin in Streptococcal infection

Cellulitis, Characteristic Reddness + Pain

Symptoms of strep throat

Erythematous, Painful | Collections of pus

Superficial, crusting lesions in kids | Name the symptom. Staph or Strep?

Impetigo | Either

Middle-aged, warm climates; exotoxins; erythematous swelling with well-demarcated, sepiginous boarder. Name the symptom. Staph or Strep?

Erysipelas | Strep

Chronic abscesses of the palmar surface of the finger tips | Name the symptom. Staph or Strep?

Paronychia | Staph

Exfoliative toxins A and B; accompany staph infections of the nasopharynx in kids. Sunburn like rash with exfoliation. Name the symptom. Staph or Strep?

Scalded Skin Syndrome/Ritter Disease | Staph

Superantigens, systemic toxins produced by growth of bacteria; hypotension, renal failure, coagulopathy, liver disease, respiratory distress, erythematous rash, soft tissue necrosis Name the symptom. Staph or Strep?

Toxic Shock Syndrome | S. aureus and S. pyogenes

Infection of the skin below the epidermisl strep more commonly causes spreading lesions due to VF. Name the symptom. Staph or Strep?

Cellulitis | Both

Subcutaneous, deep tissue facial necrosis; GABHS; other bacteria and strep serotypes; M-1 and M-3 antiphagocytic proteins Name the symptom. Staph or Strep?

Necrotizing Fasciitis | Strep pyogenes and anerobes

Superantigens released into contaminated food on warming (potato salad at a family picnic); nausea and vomiting immediately following consumption, no real infection Name the symptom. Staph or Strep?

Food Poisoning | S. aureus