Micro J210 Streptococci

  1. Can strep like staph cause impetigo?
    • -Yes streptococcus pyogenes, post-infection complications
    • -Impetigo is highly communicable, most common in daycare centers
  2. What is the general biology of strep?
    • -Gram positive, catalase negative cocci.
    • -Grow on blood agar and usually facultative anerobes
    • -Many (30+) species that often grow in animals
  3. What is a C carbohydrate?
    -A surface carbohydrate used for grouping
  4. What are the different groups of Strep?
    -A, B, C, D,....V
  5. Who determined the groups?
    -Dr. Rebecca Lancefield (Lancefield grouping of strep)
  6. What does it matter which type of disease a patient has?
    -Different groups cause different diseases which requires differenet treatment
  7. How does the patient's anti-C carbohydrate Antibody help?
    -Antiboides are non portective but are helpful for typing the agent
  8. What are the different types of strep hemolysis?
    • -Alpha (a) incomplete hemolysis (greenish color
    • -Beta (B) complete hemolysis
    • -Gamma (y) no hemolysis
  9. How does the different types of strep hemolysis help us identify the species involved?
    1 out of 3: cuts odds down 3 times
  10. Why do C carbohydrates and hemolysis not give the same results when we identify species of Strep?
    • -Separate features produce different results. Not 100% reliable, use what we can
    • -pattern of hemolysis complements C carb grouping
  11. What are the classification of pathogenic Strep?
    • -S. pyogenes, group A, hemolysis B (strep throat)
    • -S. agalactiae, group B, mostly hemolysis B
    • -S. faecalis, group D, a or B hemolysis
    • -Viridans group, nongroupable, a or y hemolysis (dental cavities)
    • -S. pneumoniae, nongroupable, a hemolysis (Otis media, pnemonia, sinuitis)
  12. Is group C Strep a pathogen?
    -No, not pathogenic
  13. What are charactistics of Group A Strep?
    • aka GAS
    • -Gram +, catalase -, B cocci, which are bacitracin sensitive (Zone of inhibition)
  14. What is the structure of Group A?
    • -Cell membrane: Variety of functions
    • -Peptidoglycan layer of cell envelople: Strength, strucutre
    • -C group carboyhydrate: means of grouping
    • -Capsule: Hyaluronic acid which is an antiphagocytic
    • -M protein: most important virulence factor: attachment helper type 1, gets rid of anti-M protein

    Releases Extracellular toxins
  15. What are the virulence determinants of group A strep that protective the pathogen?
    • -Capusle: similar to host CT component no AB. Helps resist phagocytosis by PMNs
    • -Lipoteichoic acid: Mediates attachment to epithelial cells
    • -petidoglycan: is resistant to lysosomal enzymes
  16. What is an M-protein?
    • -Anti host
    • -GAS
    • -Most important virulence factor
    • -Adhesin: mediates attachment
    • -Inactivates c3B no opsonization
    • -Anti- M antibodies are protective (90+ types)
  17. What is the protein F of cell wall?
    • -Anti host
    • -GAS
    • -Imp in adherence to throat epithelial cells
  18. What is C5a peptidase?
    • -Anti host, GAS
    • -Decrease PMN recruitment to the site of infection by neutrializing signal for chemotaxis
  19. What is streptolysins (O and S)?
    • -Anti host, GAS
    • Responsible for beta hemolysis pattern
    • SLO: damage cell membrane and mitral heart valves
    • SLS: lyse bllod cells (RBC, WBC), toxic to liver and heart muscles
  20. What is hyaluronidase?
    • -Anti host, GAS
    • -Degrade connective tissue, including heart
    • -Expressed at stationary phase of the growth cycle
  21. What is streptococcal pyrogenic exotoxin A (spe A)?
    • -Anti host, GAS
    • Superantigen: cause massive activation of T cells nonspecifically
    • -Family of toxins produced by strains that cause scarlet fever or necrotizing fasciitis
    • -Spe A is phage encoded
  22. What is DNase (streptodornase)?
    • -Anti host, GAS
    • -Helps organism spread within the infected tissue
  23. What is streptokinase?
    • -Anti host, GAS
    • -Dissolves blood clot which helps bacteria spread within tissue
    • -Therapeutic use in stroke and heart attack patients
  24. What is fragments of PG persist after infection is resolved?
    • -Anti host, GAS
    • Post-infection sequelae- Virus, bacteria: signs and symptoms due to immuje system trying to get rid of teh remaining PG layer in the tissues
  25. Does Strep have catalase?
    • -NO, cannot survive in PMN
    • -Must be extracellular pathogens
    • -Capusle and M protein protect them
  26. What organims has M proteins?
    • Only Strep. pyogenese (GAS) has M-protein
    • -Role as adhesin
    • degrades c3b and prevent opsonization
  27. What is the carriage rate for GAS?
    -only 10%, 1 of 10 carry, but may not always get sick
  28. How do impetigo and erysipelas differ?
    Infections starting from superfical epidermis (impetigo) and go deeper within the dermis (erysipelas) and subdermal area (cellulitis) and all the way into fascia (necrotizing fasciitis) and muscle and fat (myositis)
  29. What is GAS erysipelas?
    • Superficial infeciton of the skin over the face
    • Not a necrotizing process
    • Occurs in very young children
    • Systemic signs (fever, chill, leukocytosis)
    • Usually resolves completely with treatment with penicillin.
    • Produces rash that is red, swollen, warm, tender, borders defined
    • Up neutrophils
  30. What is Pharyngitis?
    • GAS, acute pharyngitis or strep throat (GAS tonsillitis)
    • -Mostly occur in young boys 5-15
    • -Spread by respiratory droplets and fomites (school)
    • -Prime strep throat season is cold season
    • -Sore throat, fever, petechiae (Dark red spots)
    • -White exudate on surface of throat
    • -Must differentiate from viral pharyngitis (4 out of 5 are viral!)
  31. What are sings and symptoms of strep throat?
    • -Throat pain, difficult swallowing, red and swollen tonsils, white patches, swollen lymph nodes, fever, headache, stomachache.
    • -Similar to sore throat by viral tonsillitis. NO white patches with viral.
    • -Strep throat is not usually associated with a cough.
    • A throat swab or rapid antigen test can determine if viral or bacterial
  32. What is Scarlet fever?
    • -GAS
    • -Erythematous rash with a sore throat
    • -Exotoxin-mediated disease (SpeA)
    • -Occurs most often in association with sore throat as a result of strep infections (18th century)
    • -Symptoms: Red swollen throat with strawberry tongue,high fever over 101, erythematous rash
    • A person can get more than once because 3 different types of Erythrogenic Toxin (Spe A, B, and C)
  33. What is strep necrotizing fasciitis?
    • -GAS
    • -Flesh-eating bacteria
    • -High risk: Weak immune system, chronic health problems (diabetes, cancer, kidney/liver disease), cuts in the skin, recent chickenpox or other viral infections that cause a rash, elderly, surgery, use of steroids b/c they lower the body's resistance to infection
  34. What is toxic shock syndrome for Strep?
    • -Starts with a local infection at site of trauma, which spreads deep within the skin tissue and realse SpeA which gets in the blood
    • -SpeA cause systemic symptoms
    • -Toxin causes systemic shock
    • -Mortality rate is high, about 30% (bactermia)
    • -Patient dies of toxic shock
    • -Amputation (removal) of affected area saves life
  35. What are features important in recovery from strep throat?
    • -Anti M protein antibody is only protective antibody
    • -Opsonic: bridges pathogen and pagocye
    • -Fixes complement: calls phagocytes to the site
    • -There are more than 90 strains of M-proteins
  36. What are treatment and prevention of Strep Throat?
    • -Penicillin stills works
    • -Amoxicillin (pink medicine)
    • -No vaccine available
  37. When should you remove tonsils?
    • Children who come down with strep throat and still have their tonsils are more than 3x as likely to catch it again and again
    • Surroudns tissue may still get infected but less severe
  38. What is rheumatic fever?
    • -Post strep infection sequelae, GAS
    • -A serious inflammatory condition that can affect many parts of the body-heart, joins, nervous system and skin
    • -symptoms appear within 5 weeks after an untreated Strep throat infection.
    • -One cause is similarities between strep antigens and heart valve proteins and heart muscle cells
    • Secondly SLO: damage mitral heart valves
    • -Occurs in children b/w 6-15
    • -Major criteria is joint pain and swelling joint to joint (migrating polyarthritis) and inflammation of heart (pancarditiis)
  39. What is post streptococcal glomerulonephritis (PSGN)?
    • -Post strep infection sequelae, GAS
    • -Occurs 10-14 days following strep skin infection
    • -Acute, immune complex mediated inflammatory disorder of the glomeruli of kidneys.
    • -Signs of kidney damage: hypertension and edema, with severe progessive renal failure
    • -Uncommon sequela of acute infection
    • -Most often in childhood ages 2-6
  40. What are characteristics of Group B Strep?
    • -Causes problems in newborns
    • -Strep. agalactiae
    • -Positive CAMP test
    • -B-hemolytidc
    • -C carb of B kind on surface
  41. What is the pathology of the most common Group B strep?
    • -Normal flora of vaginal tract (10-30% of pregnant women)
    • -Group B is most common cause of sepsis (blood infection) and meningitis (#1) in newborns
    • -Group B strep is most common infectious cause of death of newborns in USA
    • -New born gets it during vaginal delivery from infected mother
  42. What is the second risk for group B strep?
    -Immunocompromised (40% of all septicemias
  43. What is the treatment of Strep Group B?
    • -Screen pregnant women and if positive, treat with antibiotics. IV antibiotics intrapartum (during labor)
    • -Vaccine is now being explored in the US
    • -Should give it to pregnant women who are positive, 6-8 before delivery
  44. what is Viridans Streptococci?
    • -Nongroupable mixed hemolyic pattern. Many species: strep mutans, strep salivarius (oral flora).
    • -Growth characteristics: Mostly a hemolytic and optochin-resistant
  45. What is Strep mutans?
    • -Viridans strep
    • -Pathogeneiss of dental caries
    • -Evolved receptors to help them stick to the tooth enamel and produce lactic acid as a byproduct of sugar
    • -Transmitted from mother to offspring
  46. What is the epidemiology of Viridan strep?
    -100% carriers, normal flora
  47. What is SSEC?
    • -Viridans
    • -Strep. Subacute endocarditis
    • -Opportunistic infeciton of the heart
    • -Lesions of mouth (dental work) allow bacteria to enter the blood
    • -Organism bind to damaged heart valves of people with Rheumatic fever
  48. What is the treament of SSEC?
    • -Dentists take medical history before dental work
    • -Patient with history of RF must recieve penicillian a week before the dental work
  49. What is the difference between the Group A Strep heart damage and Viridans?
    • -SSEC is slower than acute, the bacteria grow on already damaged heart valves and cause more damange
    • -GAS, the reason for heart damage is GAS toxins which reach the heart by way of blood as well as a person's immune system damage the healthy heart vavles
  50. What is Strep Faecalies?
    • -Group D Strep
    • -Poop
    • -Mixed hemolytic pattern: a or b
    • -Strep faecalies or entercoccus faecalis
  51. What is the epidemiology of Strep Faecalis?
    • - Normal flora of GI tract of human (10^7 per gram of feces) and animals
    • -E. faecalis is the 3rd leading cause of nosocomial infections (1-staph, 2-E. coli)
    • -Opportunitisic
  52. What is the pathology of Group D strep?
    • -Urinary tract infections (cath)
    • -Nosocomial cause of subacute endocarditis
    • -part of mixed microbial infecion following rupture of intestine
    • -Stab wound, gunshot, rupture of appendix
    • -Broad spectum
  53. What is Enterococcus Faecalis treatment concerns?
    • -Extremely hardy and can survive for weeks on environemental surfaces
    • -E. Faecalis has become one of the most troublesome hospital pathogens due to its intrinisic reistance to many antibiotics and a remarkable capacity for developing resistance to others.
    • -Vancomycin Resistant Entercocci (VRE) are one of most important nosocomial pathogens
    • -Quarter of enterococcus genome is made-up of mobile DNA and within these regions are genes for VRE and viruelence.
    • -Great concern for transferring it to other bacteria such as staph aureus
  54. What is compliance?
    • -Adherence, means the degree to which a patient correctly follows medical advice
    • -An estimated half of those for whom meds are prescribed do not take them correctly
    • -Lack of compliance results in: complications from chronic diseases, formation of resistant infections, untreated psychiatric illness
  55. Which hemolysis is optochin and bacitracin?
    • Optochin: hemolysis a
    • Bacitracin: B
Card Set
Micro J210 Streptococci
Micro J210 Streptococci