Streptococci Flashcards
What does STREPTOCOCCI look like on gram stain?
Gram +
Cocci
Chains
(Some diplo)
General Strep characteristics
Facultative anaerobes
Catalase NEGATIVE
Carb antigens
Describe the different zones of HEMOLYSIS
NO HEMOLYSIS (gamma)
ALPHA: cloudy green zone (green heme)
BETA: clear zone - lysis
How do scientists classify strep?
Lancefield classification
detects carb antigens
A-O (all beta hemo except D)
Where is Strep A found (And transmitted)?
sometimes skin and oropharynx
transmitted droplets
What toxins allow Strep A to be invasive?
STREPTOLYSINS: hemolytic -> lyse cells
- O: oxygen labile
- S: stable in Oxygen
STREPTOKINASE:
-anti-coagulant
DNAse
How does Strep A evade phagocytosis?
Hyaluronic acid capsule
M-proteins
- adherence
- resistance
What toxins cause disease symptoms in Strep A?
SpeA, SpeB, SpeC
-proteases
Rash of scarlet fever
Strep TSS
Tell me Scarlet about yo Fever
Happens sometimes with pharyngitis-tonsillitis
Cutaneous rash
Caused by SpeA/B/C
-superantigens
Tell me about some invasive Strep A syndromes?
PUERPERAL fever: infection of uterus after childbirth
Acute PHARYNGITIS:
- strep throat
- headache, fever, chills, malaise
IMPETIGO: superficial skin infection
NECROTIZING FASCIITIS: flesh eating
-highly invasive
What are the two sequel are of strep?
Rheumatic fever
Acute Glomerulonephritis
Hey Rheuma, tell me about yo feva
Post strep throat
Heart and skin lesions
Joint pain
CROSS-REACTION of antibodies against heart and joints
Type II Hypersensitivity
PREVENTION: treat pharyngitis with penicillin
What happens with acute Glomerulonephritis?
One week post skin (or throat) infection
Hematuria, edema, hypertension
Deposition of IMMUNE COMPLEXES
Type III Hypersensitivity
How does one diagnose the Strep A?
Stain and Culture
+ cocci in chains
Beta hemolysis on blood plates
Sensitive to Bacitracin
Rapid Strep test - beads with anti-group A ab
Is Strep A (pyogenes) sensitive to penicillin?
YES!!!!
ALL STREP A ARE sensitive TO PENICILLIN
How would you diagnose Strep B
Bacitracin Resistant
Beta hemolytic (but smaller than A)
+ cocci in chains
Hydrolyze hippurate
Where is Strep B found?
Vaginal and colonic flora
Major cause of neonatal infections
-septicemia, meningitis, pneumonia
What are the ways Strep B usually presents?
- EARLY ONSET
- w/in first week
- from vagina during birth
- prevent by treating mom early - LATE ONSET
- infant to infant spread
- GOTTA CONTAIN THOSE BABAYS
How would you treat Strep B?
PENAFRIKINCILLIN
Does Group D Strep even exist?
Why yes
Enterococcus
Faecalis and faecium
Commonly in GI tract
UTI,
Wound infections
Sepsis
What’s unique about Group D?
Can grow in high salt (6.5%)
Resistant to many antibiotics
USE VANCO
Interesting facts about Strep Viridans
ALPHA hemolytic
Normal in mouth, nose, pharynx
If Strep V. Is normally found in the mouth, what disease does it cause?
INFECTIVE ENDOCARDITIS
-first transient bacteremia
Adhere to preexisting lesions
-> VEGETATIONS
What does Streptococcus PNEUMONIAE look like?
+ DIPLOCOCCI
Lancet-shaped
-short ends stuck together
Any interesting facts about Strep Pneumonia?
No
Alpha hemolytic
OPTOCHIN SENSITIVE (Viridans is resistant)
BILE SOLUBLE (Viridans is not)
No animal reservoir
How does Strep Pneumonia cause disease?
Source is usually mouth culture
Aspiration + fail to cough up -> pneumonia
What are Strep Pneumonia’s secret weapons?
CAPSULE hinders phagocytosis
IgA PROTEASE degrades surface IgA
Tell me about pneumococci’s pneumonia
Most frequent bacterial pneumonia
Cough; fever; chills; pleuritic pain; rusty sputum
Who’s at risk for pneu’s pneu?
Use ab to fight off
-spleen also helps
Immunocompromised
Sickle cell anemia or splenectomy
How does the lab diagnose pneumonia?
Examen sputum
Blood culture
Any ways to prevent Strep Pneu?
- Pneumovax 23
- CAPSULAR POLYSACCHARIDE
- old people and kids
- T-cell INDEPENDENT - Prevnar 13
- CONJUGATED VACCINE with diptheria
- infants
- T-cell DEPENDENT
