Gram Positive Bacteria + Flashcards
Staphylococcal characteristics
Aerobic cocci, catalase positive violent prolific toxins
What does it mean to be catalase positive? Catalase negative?
Catalase positive - bubbling with H2O2
Catalase negative - no bubbling with H2O2
What test determines Staph aureus? And how?
Coagulate test. Staph aureus is coagulate positive. This means there is clumping when mixed with plasma
Infections/Syndromes caused by Staph aureus (3)
Soft tissue infections
Toxic Shock Syndrome (TSST)
Staph Scalded Skin Syndrome (SSSST)
What type of toxin is SSSST and what does it cause?
Exfoliative toxin
Generalized peeling of the skin
What is the toxin of Staph aureus that is a super antigen? And what does it cause?
Enterotoxin
Causes quick onset food poisoning
What is MRSA and why is it bad?
Methicillin Resistant Staph aureus
It is penicillin resistant - produces beta lactamase which breaks up penicillin
Resist phagocytes, hard
Capsules
Attaches to fibrinogen, plastic devices, fibrin; can choke a pathway
Clumping factor
Coagulase
Produces clots in capillaries; clots fibrinogen
Enterotoxin
Superantigens causing food poisoning if ingested
exfoliatoxin
Separates layer of epidermis
Fibronectin binding protein
Attached to acceptors tissue substances
Breaks down hyaluronic acid component of tissues
Hyaluronidase
Kills neutrophils or causes them to release their enzymes
P-V Leucoidin
Breaks down fats; can break down the whole body if overreacted
Lipase
Degrade collagen and other tissue proteins
Proteases and nucleases
Makes holes in host cell membranes; unnecessary substances in, necessary out (messes up homeostasis)
Alpha toxin, beta toxin and delta toxin
Immunoglobulin binding protein
Protein A
Causes rash, diarrhea and shock
Toxic shock syndrome toxin
Converts plasminogen to fibriolytic plasma
Staphylokinase
Streptococci characteristics
Gram positive, catalase negative, aerobic, M proteins and thick cell wall
What does being catalase negative mean?
Forms in chains
What are the most common and most devastating groups of strep? (2)
Group A and Group B
C5a peptidase
Inhibits attraction of phagocytes by destroying C5a
strep virulence factor
Inhibits phagocytosis; aids in penetration of epithelium
Hyaluronic acid capsule
M protein
Interferes with phagocytosis by breakdown of C3b opsonin
strep virulence factor
Protein F
Helps with attachment to host cells
Interferes with phagocytosis by binding Fc segment of Ig
Protein G
Superantigen responsible for scarlet fever and flesh eating fasciitis
Strep pyrogenic exotoxins
Streptolysin O and S
Lyse leukocytes and erythrocytes -> cause infection
Enhance spread of bacteria by breaking down DNA, proteins, blood clots, tissue, hyaluronic acid
Tissue degrading enzymes
What is alpha hemolysis?
Partial RBC hemolysis by alpha hemolysin
What are the 2 bacteria that are alpha hemolytic? How do you tell them apart?
S. pneumoniae and S. Viridans
Optochin test
What are the results of the optichin test?
S. Pneumoniae - sensitive
S. Viridans - resistant