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59 Cards in this Set

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Characteristics of streptococcus
Morphology
Gram Stain
Oxygen
pairs/chains of cocci
Gram +
Facultative anaerobes
Examples of alpha hemolysis
viridans streptococci
Streptococcus pneumoniae
Examples of b hemolysis
Groups A, B, C and G streptococci
Streptococcus iniae
Examples of gamma hemolysis
Streptococcus gallolyticus
Enterococcus (sexually promiscuous)
Optochin disk diffusion test
to test for alpha hemolytic streptococci; S. pneumoniae is susceptible
Bile salt solubility test
to test for alpha hemolytic streptococci
S. pneumoniae is lysed by bile salts
Bacitracin test
tests for Beta hemolytic streptococci;
Only S. pyogenes is susceptible
Group D streptococci (S. gallolyticicus) is tested by
is either alpha or gamma hemolytic; ability to grow in presence of 40% bile, ability to hydrolyze esculin/optochin
very sensitive to penicillin
Enterococci resistant to
penicillin
Streptococcus pyogenes
Group A, Beta hemolytic streptococci; antigenic, antiphagocytic capsule, 60 dif M proteins, C carbohydrate, peptidoglycan; extracellular products
Peptidoglycan
made up of carbohydrate strands cross linked by oligopeptide;
functions as a phage receptor
endotoxin like activity
extracellular products produced by s. pyogenes
pyrogenic exotoxins A-J aka erythrogenic toxins AKA SPEA, SPEB, SPEC;
Streptococcal superantigen
streptococcal mitogenic Z
toxic strep syndrome caused by
superantigens - pyrogenic exotoxins; causes hypotension, multiple organ impairment
Scarlet fever rash
pyrogenic exotoxins A-J produced S. pyogenes
Pyrogenic exotoxin B
cysteine protease that degrades ECM proteins like fibronectin and vitronectin ; facilitates spread of infection
Streptolysin O
oxygen labile hemolysin neutralized by cholesterol in the skin
Antistreptolysin O titers (ASO)
used diagnostically for rheumatic fever
streptokinase
used by what bacteria?
treats what?
activates plasminogen to disrupt blood clots, produced by Group C streptococci , treats coronary occlusion
DNAse
antigenic; anti DNAse B titers used diagnostically and are more useful than ASO titers bc they are not neutralized by cholesterol during skin infections
examples of acute suppurative diseases
pharyngitis/tonsillitis; pyoderma (impetigo); cellulitis
Erysipelas
form of cellulitis; diffuse lymphangitis of skin
examples of toxin associated diseases
scarlet fever ; toxic strep syndrome "flesh eating bacteria"
post streptococcal sequelae
acute rheumatic fever (autoimmune disorder that usually follows strep throat); acute glomerulonephritis (immune complex deposition); caused by dif M types; guttate psoriasis
Treatment of group A streptococcal infections
penicillin and cephalosporin
alternatives to penicillin: macrolies (erythromycin, azithromycin, clarithromycin)
Example of Group B streptococci & patient/victim population
Streptococcus agalactiae, resistant to bacitracin

Occurs in neonates, postpartum women, and older individuals with other illnesses
Early onset neonatal infections
occur within 7 days of birth, presents with bacteremia, pneumonia, meningitis
Group B streptococci - less common illnesses are....
endocarditis, meningitis, osteomyelitis, peritonitis, pericarditis, endophthalmitis
Effect of penicillin on Group B streptococci
inhibits growth but does not kill it.
Example of Group D. streptococcus
S. gallolyticus which causes bacteremia, endocarditis, lesions of GI tract --> COLON CANCER!
Enterococcus
E. faecalis (80-90%), E. faecium (5-10%); occur in hospitalized patients; resistance to many antimicrobial agents, must combine gentamicin or streptomycin with these agents to achieve synergy
Examples of Group C organisms
S. dysgalactiae, S. zooepidemicus, S. equi
Examples of Group G
S. canis & S. anginosis; normal flora of pharynx, skin, intestinal tract, vagina
infection includes abscesses, purpural sepsis, pleuropulmonary, skin and soft tissue infections, endocarditis, bone and joint infections, bacteremia
Examples of viridans

And what they cause....
S. mitis
S. sanguis.
S. salivarius
S. mutans;

Responsible for dental caries and infective endocarditis
Microaerophilic streptococci
S. angionosus group AKA "milleri" group that includes
S. morbillorum
S. constellatus
S. intermedius ; normal constituents of bowel, pyogenic (pus-filled) foci, brain abscesses, hepatic abscesses, empyema, unusual cause of endocarditis
Streptococcus iniae
fish pathogen , causes subcutaneous abscesses; causes cellulitis within 12-24 hours
Anaerobic streptococci
Peptococcus, Peptostreptococcus
normal constituents of flora of GI and female GU tract; diabetic foot ulcers are more common in Peptococcus
Properties of Gram + bacteria
thick peptidoglycan, teichoic acid, lipoteichoic acid; cell wall has pentaglycine bridge to allow extensive cross linking in 3 d
Properties of Gram - bacteria
y thin peptidoglycan (PGN)

outer membrane (OM), made of lipopolysaccharide (LPS),

can only cross link directly;
can survive in our gut bc they are protected from bile acids

Periplasmic space - space that contains peptidoglycan layer, degradative enzymes (amylases, nucleases) and detoxifying enzymes (beta lactamase)
Beta lactam antibiotics block
peptidoglycan formation

ex. penicillin, cephalosporins
Gram neg bacteria that cannot survive in gut
Haemophilus, neisseria ; bc they have LOS instead of LPS
Lipopolysaccharide componenets
saturated lipid A fatty acids whose tight packing decrease membrane permeability; endotoxin

Core polysaccharide (KDO),

O antigen - hydrophilic polysaccharide chain, basis of serological differences ; protects against phagocytosis
features of cytoplasmic membrane
site of metabolic pathways
sensing the environment, nutrient transport, efflux (multidrug efflux and macromolecules)
Examples of obligate anaerobes (1), obligate aerobes (2), and facultative anaerobes (3)
1) clostridium perfringens, prevotella, bacteroides, fusobacterium
2)Mycobacterium tuberculosis
3) E. coli
genus characterized by sporulation
Clostridium, bacillus anthracis
Catalase present in....
staphylococcus is catalase +
Streptococcus is catalase -
Toxin production for SPEA and SPEC depends
infection of the bacteria by a phage
pyrogenic exotoxins A-J aka erythrogenic toxins aka
stroptococcal superantigen, streptococcal mitogenic exotoxin Z
Streptolysin S
extracellular product of streptococci, oxygen stable; causes surface hemolysis on blood agar plates
exSuperantigen
bind directly with Class II MHC molecules, binds only to the Vbeta variable elements of the TCR
Scarlet fever caused by:
clinical presentation:
caused s. pyogenes
strawberry tongue, sandpaper rash
Pyoderma (impetigo)
superficial skin infection due s. pyogenes and s. aureus,
think fomites
cellulitis
diffuse inflammation of both skin and subcutaneous tissues with red and tissue edema
Lymphangitis clinical manifestation
lymph node tenderness
soft tissue - streak that comes up their leg, groin hurts
Causes of cellulitis/erysipelas
coronary artery bypass (saphenous vein), axillary lymph node dissection, women with lymphedema
Toxic shock syndrome and clinical signs
From s. pyogenes; hypotension,renal impairment, coagulopathy, liver involvement, acute respiratory distress syndrome, erythematous rash, soft tissue necrosis etc....know that it is multiple organ involvement
Jones criteria for diagnosing acute rheumatic fever; major manifestations; most common feature
subcutaneous nodules, polyarthritis, erythema, carditis, chorea
most common feature: arthritis
post streptococcal glomerulonephritis manifestations
edema, hematuria, hypertension, decreased complement levels, abnormal urinary sediment, chronic renal disease
guttate psoriasis
increased frequency of Vbeta2 and involves streptococcal pyrogenic exotoxin C; keratinocyte proliferation
Enterococci resistant to
aminoglycoside, alters penicillin binding proteins, becta lactam resistance, produces beta lactamase (resistance to penicillin and ampicillin), resistant to vancomycin