Review Lesson 9: Streptococcus pyogenes Flashcards
1. Know the following characteristics about each disease studied: Genus and species name Gram reaction Cell shape Disease name Transmission Virulence factors Clinical symptoms of disease Treatment
Genus name: Streptococcus species name: pyogenes Gram reaction: + Cell shape: coccus Disease name: Transmission: Virulence factors: Clinical symptoms of disease: Treatment:
- Be able to translate the organism’s genus and species name into the English language as given in class.
Chain former, pus generating
- What are the three hemolytic reactions for classifying Strep bacteria?
Strep Classification by Hemolytic Reaction
Alpha(α) – hemolysis: partial destruction of RBC; greenish color on blood agar
Beta(β) – hemolysis: complete destruction of RBC; clear zone around bacteria
Gamma(γ) – hemolysis: no reaction with RBC
- What is the hemolytic reaction for: S.aureus and S.pyogenes?
Beta hemolytic
- On what characteristic of the bacteria cell is Rebecca Lansfield’s system of classifying Strep bacteria based?
Rebecca Lansefield Classification of Strep
Based on distinct cell wall Ags
Each Ag is designated with a letter (A – O)
(Lansefield devoted much of her life research to studying Strep bacteria)
- The M protein protects S.pyogenes from what host resistant mechanism?
M protein:
located in cell wall
interferes with phagocytosis
- What is Hyaluronidase?
Hyaluronidase: destroys hyaluronic acid; leads to tissue penetration
- What is Otitis Media?
Middle ear infection
- What is the source of the erythrogenic toxin of Scarlet fever?
Source: Prophage(virus) genome integrated into bacterial chromosome
- What category of virulence factors does erythrogenic toxin belong?
Exotoxins
- After recovery of Scarlet fever, does permanent immunity occur (listen to the audio lecture)?
Complete immunity for life
- What is a prophage?
Virus
- Why is a prophage involved in the symptoms of Scarlet fever?
Refer to handout
- If the prophage is removed from S. pyogenes, does the bacteria still cuase disease? If so, what disease?
Yes, strep throat
- What are the two late sequelae of Streptococcal pharyngitis?
Rheumatic Heart Disease, Acute Glomerulonephritis
- Is Scarlet fever a late sequelae? Why or why not?
No it’s not. It happens at the same time.
- Why has there been a dramatic decline in Rheumatic Heart Disease cases in the USA?
Early detection, antibiotics available,
- Why is Rheumatic Heart Disease described as an Autoimmune disorder?
Antibodies will attack heart valves along with S. pyrogens
- Is Rheumatic Heart disease caused by a bacteria infection to the heart?
Complications of a Strep throat infection
- What valve of the heart is damaged the most in rheumatic heart disease by antibody attack?
Mitral valve
- What percentage of patients have Carditis from Rheumatic Heart Disease?
50%
- Between what 2 chambers of the heart is the Mitral valve located?
Left atrium and left ventricle
- Can antibiotics be used to treat the symptoms of Rheumatic Heart disease? Why or why not?
Yes
- Is Rheumatic Heart disease contagious?
No it’s not contagious
- Why do patients recovering from Rheumatic Heart disease need to be on long term antibiotics if the disease is not caused by a bacteria infection?
They are more susceptible to getting and if they get it, it can mutate and be harder to treat.
- Is Acute glomerulonephritis a common or rare disease?
Rare
- What causes damage or even complete destruction to the glomerulus of the nephron kidney unit?
Complete stoppage like drain, due to immune complex disease
- What is edema?
Swelling
- Would you expect the blood pressure to initially increase or decrease because of a failure of the kidney nephron system in acute glomerulonephritis?
Increase due to all the pressure
- Is Acute glomerulonephritis contagious? Why or why not?
No
- Is Acute glomerulonephritis more common in males or females?
Male
- What is hematuria?
Blood in urine
- What is the best prevention to decrease chances of a late sequelae developing from a Strep throat infection?
Early detection, complete antibiotic treatment
- Define necrotizing.
Dead tissue
No blood supply
Anaerobic
- Define fasciitis.
White/ gray, connective tissue, thick or thin
Inflammation of
- What are the 2 virulence factors involved in the aggressive tissue damage associated with necrotizing fasciitis?
Pyrogenic exotoxin A
Exotoxin B
- What is a super antigen?
Bacteria exotoxin
Not processed intracellular by MØ for presentation to T-cells
Bind directly to T-cells without specificity
Effects 2 – 20% of T-cell population
Many T-cells die from excessive stimulation
- Why are antibiotics not very effective in treating necrotizing fasciitis?
Drug therapy: Penicillin (early) but no effect on toxins or on bacteria in necrotic tissue
- Is there a blood supply to necrotic tissue?
No
- If a surgeon debrides away necrotic tissue, what is he/she doing?
Remove dead tissue until they get to healthy pink. That way antibiotic can help treat
- What would be the reason behind removal of necrotic tissue to effect a cure?
Relieve pressure of swollen tissue
Amputation may be necessary
- Which S.pyogenes infection did we study that doesn’t involve strep throat as a primary infection?
Necrotizing Fasciitis
