Microbial pathogenesis Flashcards
Which type of bacteria have Fimbriae - type 1 pili?
Gram negatives
Which type of bacteria have CAPSULES?
Gram positives and gram negatives
What are 3 nonspecific host defenses that fight bacteria
- Physical barrier - deny access
- Complement system - attack and break down cell walls
- Phagocytes - remove debris and pathogens
How do bacteria survive complement?
- Surface proteins that inhibit or bind complement components
- Capsules and biofilms mask activating substances
How do bacteria survive phagocytosis?
- capsules and biofilms
- Exotoxins (leukocidins) - lyse WBCs
- Intracellular survival
Give examples of how bacteria survive intracellularly
- Inhibit fusion of the lysosome to the phagosome
- Escape into cytoplasm
- resist lysosomal enzymes
- inhibit oxidative pathway in once phagocytosed
Strep Pyogenes characteristics in terms of creating an immune system divergence
Has super antigens!
One of the mechanisms of evasion of proteolysis of and inactivation of secretory antibodies
expressin proteases
How does Protein A prevent opsonization?
Binds to Fc portion of IgG - e.g. in Staph Aureus
Group A strep pharyngitis can cause 2 automimmune conditions - ?
- rheumatic fever
2. Glomerulonephritis
LPS is considered what type of toxin
Endotoxin - part of the cell wall of gram negatives
Strep Pyogenes - e.g. of Exotoxin
Streprokinase + Hyauronidase + Hemolysins
Staph aureus exotoxins
Dnase + HYaluronidase + Leukocidins + Hemolysins
Tetanus toxin properties
- CNS effect
- uses retrograde transport - to spinal cord
- Inhibits release of inhibitory GABA - leads to constant contraction
- Ongoing positive extensor and flexor response
Tetanus causes - clinical manifestations
- Risus Sardonicus
2. Opisthotonus
Botulism toxin properties
- PNS effect - Peripheral!!!
- Exposure through contaminated foods
- Carried to NMJunctions
- OPPOSITE OF TETANUS - prevents PRESYNAPTIC release of Acetylcholine -
- leads to Descending Paralysis and Respiratory Arrest
- floppy baby syndrome
Molecularly what does Botulinim Neurotoxin do?
Cleaves SNARE proteins - prevents vesicle attachment and release of Ach
Consequences of low levels of Gram negative LPS
- results in fever and vasodilation
Consequences of HiGH levels of Gram negative LPS
- alarming cytokine response
- SEPTIC SHOCK
Intravascular Coagulation
An example of an opportunistic pathogen
Coag negative Staph
An example of a true pathogen
Shigella - 10 bacteria cause infection
Which bacteria are part of the skin normal flora?
- Staph (gram positive cocci)
- Corynebact (Gram + bacilli)
- Bacillus sp.. (Gram + bacilli)
Which bacteria are part of the normal orpharynx bacteria?
ALL AEROBES - dental or head and neck abscesses
- Streptococcus (gram positive aerobic cocci)
- Nisseria (gram negative aerobic cocci)
- Haemophilus ( (gram negative aerobic coccobacill))
- candida
Which bacteria are part of the normal intestinal flora
- Enterococcus sp (UTI) (Gram + aerobic cocci)
- Clostridium sp.
- Candida sp.
- Enteric bacilli, enterobacteriaceae (UTI)
- E coli, klebsiella - Bacteroides (think abscess)
