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33 Cards in this Set
- Front
- Back
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general characteristics of staph and related organisms
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gram positive
aerobic or facultatively anaerobic found in soil, skin, water |
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staph aureus big differentiators
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catalase positive
coagulase positive protein A |
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s. aureus virulence factors
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Capsule—inhibits phagocytosis
Protein A—inhibits phagocytosis, binds antibody TSST-1—superantigen Exfoliative toxins—unknown mechanism (SSSS) Enterotoxins Cytotoxins Enzymatic Factors |
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s. aureus enzymatic factors
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Catalase—breaks down hydrogen peroxide
Coagulase—leads to clotting Fibrinolysin—dissolves clots Hyaluronidase—spreading factor; breaks down connective tissue Lipases—break down lipids Nucleases—break down nucleic acids Penicillinase—cleaves β-lactam rings |
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s. epidermidis can cause
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Bacteremia
Endocarditis Urinary tract infections (also common with S. saprophyticus) Wound infections Medical device related infections (catheters, shunts and implanted devices) |
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s. epidermidis is found where?
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abundant microflora of skin
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s. aureus causes:
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1. endocarditis
2. scalded skin syndrome 3. pneumonia 4. toxic shock syndrome 5. cutaneous skin infections: impetigo 6. septic arthritis |
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Lancefeld groupings of strep
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A: S. pyogenes
B: S. agalactiae D: Enterococci non groupable: S. pneumoniea and viridans |
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All strep test how for the catalase test
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negative
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all staph are catalase
all strep are catalase |
1. positive
2. negative |
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staph saprophyticus cause
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UTI
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strep pyogens tests
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catalse negative
beta hemolytic pyr positive bacitracin sensitive pyr-positive |
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s. pyogenes virulence factors
capsule lipoteichoic acid |
antiphagocytic
adherence |
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pyogenes virulence
m protein m like protein |
adhhesin/antiphagocytic
binds Ig |
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pyogenes virulence factors
f protien pyrogenic exotoxins streptolysin S Streptolysin O |
adherence
immune system effects non immunogenic cytolysin immunogenic cytolysin |
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pyogenes virulence factors
streptokinase DNase C5a peptidase |
lyses clots; facilitates spread
degrades dna degrades C5a, a complement protien, thus inhibiting phagocytosis |
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Antiseptics
Disinfectants— Sterilants Antibacterial Chemotherapeutic Agents— |
1. can be used on living tissue
2. used on inanimate objects 3. strong disinfectants that can be used to sterilize surfaces 4.used to inhibit growth inside the body |
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inhibitors of cell wall synthesis
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1. beta lactams
2. penicillins 3. cephalosporins 4. vancomycin |
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antibiotic spectrum
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range of species for which an antibiotic is effective
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bacteriocidal
bacteriostatic |
1. kills bacteria
2. inhibits growth |
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A positive PYR test produces what color
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Red
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What tests positive for PYR
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S. pyoggenes
Enterococci |
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M protein
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1. two alpha helical proteins
2. C terminous anchored in PM and highly conserved 3. N terminous highly variable and waves around 4. binds cell surfaces, 5. prevents phagocytosis, 6. degrades complement |
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Class I M proteins
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exposed C repeats
Mediate Rheumatic fever |
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Hippurate test is positive and produces what color
what organism is positive? |
Purple
S. agalactiae |
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IgA protease
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enhances colonization
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lactoferrin/transferrin
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keep Fe concentrations low
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lactoperoxidase
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bacteriostatic
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beta lysin
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released by platelets during coagulation: bacteriocidal
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properdin
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tissue inflamation; complement, phagocytosis
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defensins
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penetrate PM and form pores allowing eflux
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3 ways to inhibit phagocytosis
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1. inhibition of fusion of phagolysosome
2. resistant to lysosomal enzymes 3. adapt to cytoplasmic replication |
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5 endotoxic effects
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1. inflamation
2. coagulate blood 3. fibrinolysin 4. internal hemmorhaging 5. hypotension |
