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79 Cards in this Set
- Front
- Back
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General Characteristic Streptococci and Enterococci |
Gram-positive cocci Catalase negative Pairs or Chains Facultatively anaerobic |
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Cell wall structure |
thick peptidoglycan layer teichoic layer C=carbohydrate layer (except viridans) Capsule in S. pneumoniae |
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Beta hemolytic Strepts |
S. pyogenes, S. agalactiae |
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Alpha hemolytic strept |
S. pneumoniae |
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M protein |
essential for virulence 80 different types M protein is related to infection |
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Streptolysin O |
BAP "stabs" hemolysis on BAP Destroys WBCs, platelets, RBCs, and other tissue Antistreptolysin O test to check |
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Streptolysin S |
Oxygen stable: can lyse RBCs and WBCs |
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Streptokinase |
prevents clotting of the blood |
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DNases A-D |
destroy foreign DNA by excreting it into surrounding area |
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Hyaluronidase |
breakdown of connective tissue at cell-cell junction |
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Erythrogenic toxin (A,B, C, and D) |
SPE A and SPE C are encoded by lysogenic phages |
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Streptococcus pyogenes clinical infections |
Pharyngitis (Strept throat) Scarlet Fever (Produce Streptococcal pyogenic exotoxins) |
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S. pyogenes skin infections |
impetigo- in very young children erysipelas- skin infection with a red rash Cellulitis- deep invasion of GAS leading to necrosis and gangrene Sepsis |
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Necrotizing Fascitis |
Flesh eating bacteria from S. pyogenes, A. hydrophila, V. vulnificus |
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Rheumatic fever |
occurs after pharyngitis inflammation of the joints, heart, blood vessels, and subcutaneous tissues Causes serious damage to heart valves |
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Acute glomerulonephritis |
pharyngitis or cutaneous infection immunological mechanisms |
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Streptococcal toxic shock syndrome |
acts as a superantigen rare but results from the toxin associated with scarlet fever |
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Capsule |
preventing phagocytosis |
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Streptococcus agalactiae |
prenatal care of expectant mothers take swabs at 35-37 weeks Newborns: <7 days old Late onset: 7 days old and up |
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S. agalactiae adult infection |
mother after childbirth or abortion
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S. agalactiae elderly |
immunodeficiency |
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Antibiotics for S. agalactiae |
penicillin; clinical response is often poor |
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Group C and G streptococcal groups |
S. dysgalactiae (beta-hemolysis), S. anginosus, and S. milleri group (Alpha-hemolysis) |
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Capsular antigens in S. pneumoniae |
82 known, vaccine, major virulence determinant |
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Pneumonia |
S. pneumoniae- prevalent in the elderly or with other diseases as a secondary infection; toxins have no known role in the disease |
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Infections of S. pneumoniae |
Pneumonia, Sinusitis, Otitis media, bacteremia |
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Characteristics of S. pneumoniae/ lab diagnostic |
gram-positive "diplococci" Capsule stain optochin susceptibility Bile-solubility |
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Bile solubility test |
desoxycholate will lyse S. pneumoniae alpha-hemolytic streptococci are resistant |
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is lytA a virulent factor |
is a factor involved in autolysis; helps to release other virulent factors |
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Treatment of S. pneumoniae |
penicillin if resistant use: erythromycin or chloramphenicol vaccine against most common antigens |
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Viridans Streptococcis |
Normal flora of URT alpha hemolysis Some require CO2 |
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Anginosus |
dental caries skin and soft tissue caries endocarditis |
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Mitis |
caries gingivitis endocarditis |
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Mutan |
caries, gingivitis and endocarditis |
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Salivarius |
caries, gingivitis, endocarditis |
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Most common cause of subactue bacterial endocarditits |
Viridan stertococci an opportunistic pathogen |
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Treatment of viridan |
penicillin vancomycin resistant |
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Group D and Enterococcus |
S. gallolyticus |
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Group D infections manifest as |
endocarditis, UTIs, wound infection |
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Distinguish non-enterococcus and enterococcus |
Enterococcus is resistant to penicillin Group D is susceptible |
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Separating Group D and Enterococcus by PYR |
Enterococcus + (6.5% salt +) Group D - (6.5% salt -) both bile esculin positive (+) |
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Enterococci and Antimicrobial resistance |
resistant to several agents VRE |
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Streptococcus like organisms |
vancomycin resistant |
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Gemella |
gram-negative, cocci in pairs, tetrads, clusters or short chain |
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Aerococcus |
alpha hemolytic tetrads weak catalase growth in 6.5% salt |
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A. viridans |
BEA positive PYR positive |
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A. urinea |
BEA negative PYR negative |
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Lactococcus |
UTIs endocarditis |
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Leuconostoc |
coccoid morphology used in agriculture |
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Pediococcus |
tetrads, pairs, and clusters bacteremia, abscesses, meningitis resistant to vancomycin |
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Abiotrophia and Granulicatella |
Satellite colonies Nutritionally variant require sulfhydryl |
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Facklamia |
gram positive cocci short chains or diplococci reduced susceptibilities to beta lactams, erythromymcin, clindamycin Difficult to manage |
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PYR positive |
S. pyogenes |
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PYR negative |
S. dysgalactiae (C &D) S. anginosus group (A, C, F, G) |
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Susceptible to Bacitracin |
S. pyogenes |
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CAMP positive and hippurate hydrolysis positive |
S. agalactiae |
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VP negative |
S. dysgalactiae (C, G) |
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VP positive |
S. anginosus (A, C, F, G) |
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Optochin susceptible Bile solubile |
S. pneumonia |
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Optochin resistant not bile solubile |
Viridans group |
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Lancefield grouping |
differentiating Beta hemolysis Streptococci Cell wall carbohydrate |
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Bacitracin susceptibility (A disk) |
Identifies group A strepts other groups of beta hemolytic strept resistant |
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CAMP test |
detects the production of enhanced hemolysis Group B |
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Hippurate hydrolysis |
Differentiates group B Streptococci: hydrolysis sodium hippurate
Hippuricase hydrolyzes hippuric acid to glycine |
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PYR hydrolysis |
Hydrolyzed by group A streptococci and Enterococcus Group A and D (S. pyogenes and Enterococcus) |
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Leucine Aminopeptidase (LAP) |
hydrolyzed by the enzyme leucine aminopeptidase, produced by bacteria
Highly visible red Schiff base
S. pneumoniae, and S. pyogenes, Enterococcus |
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Voges-Proskauer (VP) Test |
Detect acetoin Red or Pink is positive Anginosus is positive |
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BGUR test |
enzyme found in gourp C and G |
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Bile Esculin Test |
ability to grow in 40% bile esculin streptococci group D antigens |
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Salt-Tolerance Test |
Differentiates group D from enterococci Enterococci grows |
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Optochin susceptibility |
ethylhydrocuprein hydrochloride greater than 14/16mm disk susceptible S. pneumoniae |
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Bile solubility |
amidase enzyme: under bile salt or detergent lyses cell wall S. pneumoniae
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Nucleic Acid Probes |
RT PCR DNA probe tests |
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Susceptibility testing S. pneumonia |
Penicillin Alternatives: Erythromycin |
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E test |
susceptibility of clindamycin or erythromycin MIC |
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Bacteria that causes necrotizing fascitis |
S. pyogenes A. hydrophilia V. vulnificus |
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Differentiate between Group A (S. pyogenes) and Group B (S. agalactiae/Beta-hemolysis) |
Group A susceptible Group B resistant |
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Pneumonia symptoms |
chills, cough, dyspnea leads to edema of the lungs complicated by pus build up and pleural fusion high mortality even with treatment (5-10%) |
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What cannot be differentiated by Lancefield grouping? |
S. pneumoniae |
