Save
Busy. Please wait.
Log in with Clever
or
show password
Forgot Password?
Don't have an account?  Sign up 
Sign up using Clever
or
Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account. Your email address is only used to allow you to reset your password. See our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
focusNode
Didn't know it?
click below
 
Knew it?
click below
Don't Know
Remaining cards (0)
Know
0:00
edit
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

β-Hemolytic Strept

Microbiology ppt 4 - β-Hemolytic Streptococci

QuestionAnswer
Bacterial genus's included in Streptococcaceae family Streptococcus spp. & Enterococcus spp
Streptococcus pyogenes (β-hemolytic) causes... Strep throat -May be carried in URT but always considered clinically relevant when isolated
Streptococcus pneumoniae (α-hemolytic) causes.. Leading cause of bacterial pneumonia and menigitis -NF in URT; pathogenic in LRT
Streptococcus colony morphology BA: small to medium, gray/gray-white, translucent colonies. May be hemolytic. Same on CHOC PEA or CNA: small gray or gray white. Faculative anaerobes but many grow best in CO2
Which strept falls under Lancefield Group A? Streptococcus pyogenes
How does Lancefield grouping work? Lancefield grouping is done by a latex bead test for agglutination. The beads are coated in ways that differentiate cell wall structures.
Two most clinically significant β-Hemolytic Streptococcus spp. S. pyogenes and S. agalactialactiae
Characteristics of Streptococcus pyogenes -Lancefield group A -Carried on nasal, pharyngeal and sometimes anal mucosa. -Not considered NF -Aggressive pathogen! Colony morphology: GP in chains
Streptococcus pyogenes spectrum of disease Localized infections: Acute pharyngitis, skin infections such as impetigo, erysipelas. Systematic infections: Necrotizing fasciitis, bacteremia, myositis Poststreptococcal diseases: results from hosts antibody response, ex- rheumatic fever
Virulence factors of S. pyogenes (Streptolysin S) Streptolysin S: responsible for most β-hemolysis -oxygen stable (lyses RBC's, WBC's and PLT's in presence of air) -Non-immunogenic: not able to produce an immune response/doesn't produce antibodies. -Inactivated by acid from fermentation of glucose.
Virulence factors of S. pyogenes (Streptolysin O) Streptolysin O: Oxygen labile -> hemolysis only in absence of air. Inactivated by oxygen. -Immunogenic, except it won't produce ab's with skin infection due to cholesterol on skin. -Lysis same cells as stretolysin S Mostly in Group A
ASO Antistreptolysin O - presence indicates infection within previous 2 months.
True or False: A small percentage of people with a complication related to a strep infection will not have an elevated ASO True! Especially true with glomerulonephritis
Virulence factors of S. pyogenes (SPEs) Streptococcal pyrogenic exotoxins (SPE) -Acts as superantigens which can put the body into shock by triggering a huge immune response. -Erythrogenic toxins - Causing redness of the skin by inducing inflammation with t-cells and inflammatory cytokines
Virulence factors of S. pyogenes (M Protein) -Only in group A strep -Rheumatic Fever: AB's produced against M protein can cross-react with human heart tissue, fever, polyarthrits etc. -Antiphagocytic -Acute glomerulonephritis
Virulence factors of S. pyogenes continued Protein F - Adherence to epithelial cells Enzymes and hemolysins - invasion or tissue destruction, stretolysins, streptokinase, DNase, hyaluronidase Hyaluronic acid capsule - Inhibits phagocytosis
Direct detection of S. pyogenes Antigen Detection: Commerical kits using latex agglut. or ELISA (collect 2 swabs) Molecular Testing for specific DNA, RNA or RNA sequences Gram stain: GPC, Pairs or chains, may be oval. May appear gram neg if culture is old or pt is on antibiotics
If a GPC is catalase negative... and is B-Hemolytic.. it is most likely... S. pyogenes or S. agalactiae
Latex agglutination testing detects ___ antigen in cell wall C
Test that confirms Group A strep is a S. pyogenes Using a PYR test, a positive bright red/pink indicates S. pyogenes or an Enterococcus
Is bacitracin sufficient for identifying S. pyogenes? No, as groups c and g are also susceptible, the test is no longer recommended as it isn't specific.
What tests are used to identify S. pyogenes? PYR + Hippurate - CAMP - Latex agglut- Group A
Antibodies produced in patients with disease caused by S. pyogenes -Anti-streptolysin O (ASO) -Anti-DNase B -Anti-streptokinase -Anti-hyaluronidase
Which beta-hemolytic strep falls under Lancefield group B S. agalactiae
S. agalactiae NF? Yes of the female genital tract and lower GIT
S. agalactiae related infections Infections are most often associated with neonates - fever, sepsis, meningitis, respiratory distress, lethargy, hypotension. Can be transferred to baby in utero or during birth.
S. agalactiae virulence factors -Capsule: Interferes with phagocytosis & activation of complement cascade.
Group B strept colony morphology Grows on BA, CHOC, PEA and CNA -Additional culture medium: Todd-Hewitt enrichment broth to detect genital carriage during pregnancy. -Colonies slightly bigger than group A with narrow zones of hemolysis and some are gamma hemolytic.
Direct detection of S. agalactiae Antigen detection: -Commerical kits using latex agglutination. -Quick tests for dx of neonatal sepsis and meningitis. -Developed for CSF, serum and urine. -Molecular Test: PCR for cfb gene (for CAMP factor)
ID of Group B Streptococcus Catalase - Neg Latex - Group B Hippurate pos CAMP pos
What are positive and negative examples on the Hippurate Test Pos is deep blue/purple and is S. agalactiae Neg is clear or slightly yellow and is S. pyogenes False pos if incubation time is exceeded and can't be used for non hemolytic streptocci.
CAMP test pos and neg result Pos = arrow head of hemolysis, S. agalactiae Neg = no arrow head, ex S. pyogenes
Beta Hemolytic group C strept associated health issues Pharyngitis and tonsillitis from pts with underlying diseases (COPD, Diabetes, Immuno-suppression and HIV) -NF -Occasionally associated with accute pharyngitis
Beta Hemolytic group F & G strept diseases Group F: cellulitis, deep tissue abscesses, bacteremia, osteomyelitis and endocarditis. Group G: often associated with malignancies and sometimes with pharyngitis.
Drug of choice for all infections caused by beta hemolytic streptococci? Penicillin
Created by: moreandmore
Popular Biology sets

 

 



Voices

Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!
"Know" box contains:
Time elapsed:
Retries:
restart all cards