STAPHYLOCOCCI

• Catalase


  Enzyme that can convert hydrogen peroxide to water and oxygen
• Staphylococci spp.


  Grow in aerobic or microearophilic conditions
• Antibiotic Resistance Mechanisms

  Beta-lactamase - Oxacillin, Nafcillin, and FLudoxacillin

  mecA gene - produces penicillin binding protein

  vanA gene - causes resistance to vancomycin
• Staphylococcus aureus


  Common bacterium that causes infection in most organ systems, whose primary colonization site is the nostrils
• Sepsis


  Decreases blood pressure, hypotension, low blood perfusion
• Biofilms


  Makes it harder for antibacterial agents to penetrate and kill bacteria
• Toxic Shock Syndrome Toxic 1 (TSST-1)


  Produces at the site of infection and can enter the bloodstream; can be found in vagina/surgical sites
• Panton-Valentine Leukocidin Toxin (PVL)


  Pore. forming toxin that affects leukocytes and results in the release of inflammatory mediators
• Hemolysin


  Pore forming toxin that affects erythrocytes to release Iron in the blood
• Hemolysins released by S. aureus

  Alpha - lysis of RBC by destroying their cell membrane

  Beta - ability to degrade to sphingomyelin

  Delta - ability to disrupt biologic membranes
• Exfoliatin


  Causes Bullous impetigo which could lead to Staphylococcal Scalded Skin Syndrome (SSSS) also known as “Ritter’s disease”
• Enterotoxin


  Released when S. aureus lands on food
• Methicillin-resistant S. aureus Infections


  Due to high usage of antibiotics
• Vancomycin-intermediate S. aureus (VISA)


  S. aureus could adapt easily
• Vancomycin-resistant S. aureus (VRSA)


  With complete resistance
• Staphylococcus epidermidis


  Most dominant bacteria on the human skin that produces adherent biofilms made up of exopolysaccharides
• Prosthetic Joint Infection


  Contamination at the time of surgery
• Staphylococcus saprophyticus


  2nd most common cause of UTI and usually presents as symptomatic cystitis
• Streptococcus spp.


  Gram (+) cocci, non-motile, non-spore forming, Catalase (-)
• Hemolysis

  Alpha - strep-viridans

  Beta - strep-pyogenes

  Gamma - enterococcus
• Lancefied Classification A-H and A-K. A,B,C,F,G


  Causes disease in humans
• Streptococcus pyogenes


  Group A Beta Hemolytic Strep and pus producing
• Streptococcus Fibrinogen Binding Protein


  Used to attach to host cells
• M Protein


  Penetrates and projects from the streptococcal cell wall
• Hyaluronidase


  Used for connective tissues in blood vessels
• Streptolysin O and S

  O - agar plates

  S - surface of blood agar plates
• Streptococcal pyrogenic exotoxins

  A & C are superantigens
• Streptococcal pharyngitis


  Fever, painful swallowing, red, swollen tonsilitis with pus
• Impetigo


  itchy honey-colored crusts on skin
• Erysipelas 


  warm, painful, raised lesions
• Necrotizing fasciitis


  Fever and purple discoloration with pain over infected area
• Scarlet Fever


  Bright red skin rash that feels like sand paper, flushed red face but pale around mouth
• Acute Rheumatic Fever


  Joint inflammation, heart damage, nodules, erythema marginatum
• Syndenham’s chorea 


  Rapid involuntary movement of the face and hands
• Streptococcus agalactiae

  • Group B, CAMP and Hippurate test (+), facultative member of the normal flora in vagina, and most common cause of neonatal meningitis
  • Hydrolyze sodium hippurate
• Chorioamnionitis


  Bacteria ascends from the vagina into the uterus
• Cystitis


  Bacteria infects the urethra
• Neonatal pneumonia


  Enters the respiratory tract during natural delivery
• Neonatal meningitis


  Passes through the Blood Brain Barrier
• Septic Arthritis


  Bacteria infects joints of the newborn