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Streptococci
Micro
| Question | Answer |
|---|---|
| Pyogenic cocci are (obligate intracellular, obligate extracellular, facultative intracellular) organisms? | Obligate extracellular (staph and strep cannot live in PMNs) |
| What are cocci pairs (lancet shaped) typical of? | Strep pneumo |
| Streptococci are catalase (positive or negative)? | Negative (distinguishes them from Staph) |
| What does staph aureus look like on blood agar? | Yellow ("gold"); with a clear zone around them (B-hemolytic) |
| Are polysaccharide antigens t-dependent or t-independent responses? What antibody is formed? | T-independent; Form IgM antibody |
| Can infants form an immune response to polysaccharide antigens (like those given in older Strep Pneumo vaccines)? | NO - cannot form T-independent immune response (need conjugate vaccines) |
| Streptococci pneumo is (non-hemolytic, Beta-hemolytic, Alpha hemolytic)? | Alpha hemolytic |
| What color will strep pneumo display if grown on blood agar? What causes this color? | Are very mucoid looking (glistening, goopy) and around the colonies look Green due to breakdown of hemoglobin by pneumolysin |
| What causes certain strains of bacteria which look glistening and goopy on agar? | polysaccharide (encapsulated organisms) |
| Streptoccoci pneumo is Bile (soluble or insoluble)? | Soluble (autolytic enzymes elicited when bile is added) |
| What other autolytic enzyme inducing compound (aside from bile) will result in lysis of a colony in streptococci pneumo? | Optochin |
| What are the different ways to detect polysaccharide capsules? | Quellung reaction; latex agglutination; co-agglutination |
| What is co-agglutination? | Killed staph aureas uses it's protein A to bind antibodies of polysaccharides |
| What are the surface adhesins for streptococcus pneumoniae? | PspA and Choline-binding proteins |
| What is a major viral predisposing factor for Streptococci pneumonia infection? | Influenza infection |
| What are the clinical manifestations of Pneumococcal pneumonia? | Usually Lobar; sudden onset chills, fever, pleuritic pain, rusty collered sputum (always take blood cultures) |
| What are some other Streptococcus pneumonia infections of the upper respiratory tract (aside pneumonia)? | otitis media, mastoditis, sinusitis |
| What are some extrapulmonary infections caused by S. pneumo (aside upper respiratory infections)? | meningitis (especially due to skull fracture); septic arthritis; endocarditis |
| What do you treat acute otitis media caused by S. pneumonia? | amoxicillin |
| What do you treat sinusitis caused by S. pneumonia in children and adults? | amoxicillin (both); quinolones (adults) |
| What do you treat pneumococcal pneumonia? | third generation cephalosporins |
| What do you treat meningitis caused by S. pneumo? | vancomycin plus B-lactam |
| What vaccine is currently recommended for children to prevent S. pneumo? | PCV13 - conjugated polysaccharides with 13 serotypes |
| What vaccine is recommended for adults , chronic and immunosuppresed patients (asthma and smokers) to prevent S. pneumo? | 23PS - non-conjugated vaccine (all polyvalent polysacharride with 23 serotypes) |
| What is group A strep also commonly called? | Streptococci pyogenes |
| This carbohydrate antigen is part of the cell wall of Strep pyogenes and often used in rapid detection tests? | Lancefield group A antigen |
| Group A strep is (alpha-hemolytic, beta-hemolytic, non-hemolytic)? | B-hemolytic (just like S. aureus) |
| Is group A strep sensitive to bacitracim? | Yes |
| Group A strep is catalase (negative/positve)? | Negative |
| Group A strep is PYR (positive or negative)? | Positive (pyrrolidonyl arylamidase) |
| Can vaccines against the capsule of Group A strep be made? | No; capsule has hyaluanic acids and thus it would react with human cells as well |
| What is the major virulence factor of strep pyogenes? | M protein (binds to epidermis; anti-phagocytic) |
| Why don't we use protein M to make a vaccine against strep pyogenes? | sequence homolgy between mammalian proteins (anti self) |
| What are some toxin mediated responses that S. pyogenes is capable of? | scarlet fever and toxic-shock like syndrome (due to exotoxins) |
| What are some extracellular virulence factors made by group A strep? | Pyrogenic exotoxins (superantigens); Streptolysin O; DNAase; Streptokinase; C5a peptidase |
| What does streptolysin O do and how is it clinically significant? | (produced by S. pyogenes); lyses red blood cells; antigenic (antibodies in throat infections made can be detected by anti-streptolysin ASO test |
| This virulence factor is made by group A strep and is used by surgeons during enzymatic debridement? | Streptokinase |
| What are the two general classes of diseases caused by group A strep? | suppurative vs non-suppurative |
| What are the 2 non-suppurative diseases caused by group A strep? | Rheumatic fever and Acute glomerulonephritis |
| What is a way to detect wether or not a person had a strep A infection who now presents with rheumatic fever /glomerulonephritis? | Antibody titer to Streptolysin O or DNAases |
| What does the throat look like in Streptococcal pharyngitis? | inflamamtion with petechia or small red spots on the soft palate |
| Strawberry tongue, circumoral pallor, desquamation. What bacteria cause the symptoms due to a toxin? | Streptococal pyogenes (group A strep) |
| What do you use to treat streptococcal pharyngitis? | penicillin |
| What type of pyodermas can S. pyogenes produce? | impetigo, erysipelas, cellulitis, and necrotizing fasciitis |
| What is the differnce between toxic shock caused by Staph and Strep A? | Strep A and toxin are in the blood (bacterimia) vs Staph where the bug is localized and making the toxin. (also necrotizing fasciitis present with group A strep) |
| What must patients with rheumatic fever be placed on for the rest of their lives? | penicillin (prevent further antibody response to protein M and acute heart damage) |
| What neurological abnormalities, which is abrupt in onset, and episodic, is associated with group A strep infection? | PANDAS syndrome (pediatric autoimmune neuropsychiatric disorder associated with group A strep) |
| What treatment is given for group A strep infecitons? | Penicillin G |
| What is the current most common cause of neonatal meningitis? | Group B strep infections |
| Group B strep is catalase (positive or negative)? | Negative |
| Group B strep is (alpha hemolytic; B hemolytic; non-hemolytic)? | Beta hemolytic |
| Group B strep is bacitracin (insensitive or sensitive)? | Insensitive |
| Group B strep will test positive or negative for CAMP? | Positive (extracellular protein produced by group B that will react with a B lysin of S. aureus) |
| What is the treatment for group B strep? | Penicillin G and aminoglycoside |
| What is given to a pregnant women with a history of a baby born with group B strep? | Penicillin G |
| A baby is born with meningitis and you as a physician would like to rule out group A strep (you think its group B strep)? What test could you give? | Bacitracin (group B will culture and grow because its resistant); CAMP (Broup B will be positive) |
| This organism is part of the normal flora of the gut, and a leading cause of hospital aquired secondary infection (due to catheters, etc)? | Enterococci (facalis and faecium) |
| enterococci are (beta hemolytic; alpha hemolytic; non-hemolytic)? | Alpha and NON (rarely beta) |
| Enterococci are catalase (negative or positive)? | Negative (all strep) |
| What Streptococci is th eonly one to be able to survive Bile and Sodium chloride? | Enterococci |
| Enterococci are PYR (negative/positive)? | Positive |
| These two streptococci produce PYR. What is a lab test to separate the two? | Enterococci and group A strep; (either Bile or hemolysis - group A is B hemolytic and degrades on bile) |
| What clinical syndromes are caused by enterococci? | UTI, bacteremia, subacute endocarditis, and Wound and tissue infections |
| Viridans streptococci is (alpha hemolytic, beta hemolytic, non-hemolytic)? | Alpha |
| Viridans streptococci is optochin (sensitive, resistant)? | Resistant |
| Viridan streptococci is bile (sensitive, resistant)? | resistant |
| Viridans streptococci is PYR (positive/negative)? | Negative |
| What gram positive, catalase negative, alpha hemolytic organism is responsible for dentists to ask if you had previous heart disease, which, if you had a damaged heart valve would predispose you to one of the effects of this organism? | Viridans streptococci |
| Which is part of the normal flora of the skin and nares (S. aureus, S. pyogenes, Both)? | S. Aureus |
| Which causes Bullous impetigo (S. aureus, S. Pyogenes, Both)? | S. Aurues |
| Which one causes food poisoning (S. aureus, S. pyogenes, Both)? | S. aureus |
| Which one causes pharyngitis (S. aureus, S. pyogenes, Both)? | S. pyogenes |
| Which one causes necrotizing fascitis (S. aurues, S. pyogenes, Both)? | S. pyogenes |
| Which one is B hemolytic (S. aureus, S. pyogenes, Both)? | BOTH |
| Which one is catalase negative (S. aureus, S. pyogenes, both)? | S. pyogenes |
| Which one is a pus former (S. aureus, S. pyogenes, Both)? | BOTH |
| Which one causes Impetigo (S. aureus, S. pyogenes, BOTH)? | BOTH (S. aureus causes Bullous impetigo) |
| Which one causes toxic shock syndrome and associated bacteremia (S. aureus, S. pyogenes, BOTH)? | S. pyogenes (S. aureus is localized and secreting the toxin) |
Created by:
lamsonma
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