Host damage, Opportunistic and Nosocomial Infec (Gram - aerobes) Flashcards
membrane active exotoxins
- S. aureus hemolysin (pore former, lyses rbc)
- alpha toxin (C. perfiringens)
- listeriolysin (destroyed phagocyte membrane)
MOA of botulinum/tetanus neurotoxins
protease
MOA of shiga/shiga-like toxins
endonuclease
MOA of cholera, pertussis, diptheria toxins
ADP-ribosyltransferase
MOA of c. diff toxins A/B
glucosyltransferase
staph features allowing long survival
desiccation tolerant
heat tolerant
high salt tolerant
inhibitors of phagocytosis
- protein A
- polysaccharide capsule
- coagulase
S. epidermidis Adhesins
fimbriae (pili)
AtlE
capsular polysaccharide
tx for S. saphrophyticus UTI
same as other UTIs (Tmp-SMX)
lancefield is based on
cell wall carbohydrate antigens
erysipelas
infection of upper levels of dermis
red rash, slighty swollen with well-defined borders, warm and tender to touch
seen in GAS (pyogenes)
GAS strep symptomatology can mimic
EBV or CMV
major GAS virulence factor
M factor
- attachment
- resists phagocytosis
- resists complement
GAS exotoxins in nec fasc
streptomycin O/S (beta-hemolysis)
streptokinase (activates plasminogen)
DNAse B
strep bovis is common in bowel flora, but when in bloodstream correlates ~50% with
colon cancer
subacute endocarditis
viridians
encounter - pneumococcus
aerosols, mucus exchange, fomites?
virulence fx pneumococcus
IgA protease
phosphoryl choline
pneumolycin (pre-forming toxin)
polysaccharide capsule
pneumococcal vaccine
children/elderly –> conjugated vaccine (promotes T cell response)
or
non-conjugated (splenectomy pts, preexisting lung cond.)
superantigen MOA
Superantigens couple the T cell receptor to MHC class II molecules on macrophages without a specific ligand in the T cell receptor.
This inappropriate coupling leads to a massive pro-inflammatory responses, due to elevated levels of TNFα, IFN-γ, etc and results in toxic shock.
opportunistic infections
organisms multiply/spread when immune system is compromised
*pseudomonas aeroginosa is prototypic opportunistic pathogen
pseudomonas pathogenicity factors
- pili/adhesions
- LPS, capsule, biofilm
- LPS, toxins, motility, chemotaxis
- sigma factors, two-component regulatory systems, quorum sensing
pseudomonas colonies
mucoid
blue-green
fruity
pseudomonas tx
b-lactams, fluroquinolones, aminoglycosides
K. oxytoca
neonatal bacteremia
EtOH, DM, chronic lung disease
susceptible to klebsiella
currant jelly
klebsiella pneumoniae
klebsiella pneumoniae resistance
ESBL
carbapenem resistant strains
