Biology 431 Gram ( ) Cocci Chapters 22-24

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Biology 431Gram () CocciChapters 22-24
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StaphylococcusMajor groups - coagulase ()
aureus vs. (-) others.

• External Structures
• Capsule - polysaccharide, 11 serotypes,
  antiphagocytic
• Peptidoglycan endotoxin-like - fever, WBC,
  complement
• Teichoic acid binds host mucosal fibronectin
  receptors
• Protein A - binds IgG, prevents Ab clearance

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• Toxins - mostly aureus
• Cytotoxins (A, B, D, G) - hemolytic, mostly
  WBC/RBC
• Exfoliative - protease, target skin desmosomes
• causes SSSS/neonates impetigo/nosocomial, AIDS
• Enterotoxins (50) - 8 different,
  acid/heat-stable, Sag
• TSS (15) - tampon-associated, invasive and SAg

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• Flesh-Eating/Invasive Enzymes - most aureus
• Catalase neutralize H2O2, metabolic or
  phagocytic
• Hyaluronidase hydrolyze connective tissue,
  spread
• Lipase survival in sebaceous areas, invasion
• Fibrinolysin/Staphylokinase dissolve fibrin
  clots
• Penicillinase plasmid-passed antibiotic
  resistance
• Coagulase covered in lab

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• Other aureus Diseases - Most Hematogenous
• Enterocolitis - C. difficile-like, long-term
  antibiotics
• Bacteremia - bacteria in blood, 50 nosocomial
• Endocarditis - 50 fatal rapid deterioration
• Pneumonia - several, all associated with
  abscesses
• Osteomyelitis - bone infection, pain, high fever

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• Non-aureus Diseases
• UTI - mostly saprophyticus, lab
• Endocarditis - mostly epidermidis and
  lugdunensis
• Native heart valves - malformed, genetic, disease
• Nosocomial plastic devices, prosthetics - 1 year
  later

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StreptococcusHemolysis subgroups - lab

• External Structures - pyogenes
• Capsule - polysaccharide, Lancefield (surface
  A-G)
• pyogenes Group A - 10 weight, NAG/rhamnose
• M Protein - 100 types, antiphagocytic/opsonization
  
• Lipoteichoic acid binds host mucosal fibronectin

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• Other Virulence Factors - pyogenes
• Pyrogenic Exotoxins - SAg, toxic shock, rash,
  fever
• Streptolysin - hemolytic for RBC, WBC - more in
  lab
• Streptokinase - lysis of fibrin clots, disease
  spread
• DNAse - nucleases, target pus to reduce viscosity
• C5a Peptidase - destroys key complement protein
• Outcomes - pharyngitis, varying skin infections,
  Scarlet Rheumatic Fever/Arthritis,
  glomerulonephritis.

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• agalactiae - Group B, beta hemolytic
• Historically puerperal sepsis - childbirth, war
  wounds
• Currently - neonatal septicemia, pneumonia,
  meningitis
• Group B Carbohydrate - NAG/rhamnose/galactose
• Colonize lower GI GU, 10-30 pregnant women GU
• 60 infants colonized, increases with premature
  or prolonged delivery post-delivery infection
  possible.

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• pneumoniae - Nongroupable, alpha hemolytic
• Diseases pneumonia, sinusitis, otitis,
  meningitis
• Polysaccharide capsule - 90 types, antiphagocytic
• IgA protease - digests IgA, prevents binding
• Pneumolysin - digests cholesterol, pores
• Pneumococcal vaccine, anti-capsule for 23 strains
• Viridans group also nongroupable - cavities,
  endocarditis.

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Enterococcus Will not cover extensive list of
others, Table 24.1-2

• Enterococcus - Virulence, Disease, Treatment
• Surface adhesin protein - bind GI and vaginal
  mucosa
• Secrete - hemolysins, proteases, bacteriocins
• Inherently resist many antibiotics serious
  nosocomial...
• UTI, surgical (peritoneum/heart), blood
  (endocarditis)
• Careful antibiotic selection, use - new drug
  development
• gallinarum more prominent human GI flora
  faecalis more disease-associated.

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