Infectious Disease -- Streptococci Review Flashcards
Streptococcal patterns of disease?
Spreading of suppurative skin infections
Post-streptococcal hypersensitivity disease
Manifestations of Streptococcal spreading suppurative skin infections
Cullulitis
Erisypelas
GABHS
Impetigo
Manifestations of post-Streptococcal hypersensitivity disease?
Rheumatic Fever
Immune Complex Glomerulonephritis
Three groups of Streptococcal infections
Group A
Group B
Viridans
Whats Group A Strep all about…
S. pyogenes
beta hemolytic
Pharyngitis/post streptococcal disease
Whats Group B Strep all about…
Perinatal Sepsis/Newborns, UTIs
What is Strep viridans all about…
Grouped as alpha hemolytic
Major cause of subacute bacterial endocarditis
Why care about strep mutans?
Major cause of dental caries
Streptococcal virulence factors?
Call wall polysac./capsules (M Proteins)
Enzymes – streptokinase, streptolysin O, S
Erythrogenic toxins
Purpose of Cell Wall polysaccharides/capsules?
Prevention of phagocytosis
Significance of Streptococcal enzymes (streptokinase, streptolysin)
Contribute to ability to spread through tissues
What do Streptococcal erythrogenic toxins cause
Skin Rash
Initial presentations of Group A streptococcal disease
Acute Pharyngitis/URT
Scarlet Fever
Symptoms of Group A Streptococcal Acute Pharyngitis?
Reddness, Edema, Pain
Fever, Chills
Punctate abscess in tonsillar crypts
Peritonsillar, retropharyngeal abscess formation
What is Group A Streptococcal Scarlet Fever
Severe, prolonged group A pharyngitis
Symptoms of Group A Scarlet Fever
Febrile Exanthematous Disorder
Erythrogenic toxin (causes violaceous red rash on trunk)
Strawberry tongue
Desquamination of Skin
What does Febrile Exanthematous Disorder look like
Unraised blotches all over body
Describe presentation of post-streptococcal glomerulonephritis
1-2 weeks after strep throat
Immune-complex mediated
Can cause renal failure
Describe presentation of rheumatic fever
Weeks-months+ after infection
Fever, Joint Disease, Myocardial/Valvular disease
Eventually, long standing damage to mitral/aortic valves
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
What to Streptococcal skin infections look like?
Cellulitis, pyoderma
Extensive spreading reddness, swelling, pain
Rare complications of Streptococcal skin infection
Abscess, Pustule
Necrotizing fasciitis
Describe impetigo
Contagious skin infection in kids involving horny (superficial) skin layers
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
- Cell wall PS/Capsules (M Proteins)
- Streptokinase, Streptolysin O, S
- Erythrogenic Toxin
Antibodies to Group ____ Streptococcal antigens may cross react with human tissue and cause rheumatic fever
A
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
