Histophilus somni Flashcards
what speceis does it include
haemophilus somnus
H agni
histophilus ovis
what animals is it specific for
specific for bovine and sheep
what does it require to grow
blood and CO2
what blood factors does it require
does not require X nor V factor
color
most have yellow pigment
hemolysis?
weakly hemolytic or non hemolytic
location
ruminant genital and respiratory tracts
why dissemination (spreading)
due to inflammation of endothelium
hat is the hallmark of this pathogen
vasculitis
what is required for disease to develop
stress and viral infection
feedlot disease
diseases
thrombotic meningoencephalitis (TME)
pneumonia (BRDC, shipping fever)
myocarditis (biofilm formation)
reproductive failure (abortion, infertility)
arthritis
bacteremia
what does biofilm formation do
bacteria are more resistant to antibiotics and host defenses
induce less inflammation
virulence
endotoxin (LPS) – take up celiac acid
IgG Fc receptors (IbpA) – protect from host defenses
inhibit phagosome-lysosome fusion – survives in phagocytic cell
cytotoxin as part of motif of IgG binding to protein A – toxic to bovine endothelial cells and macrophages
compromising factors
virulent infection
stress
previous infection
disease due to host inflammation
immunity
virulence largely due to avoiding host immune system
antibodies normally present should be protective, but no evidence of this
vaccination
bacterins limited in effectiveness
effective vaccines not developed
do vaccines protect against respiratory disease
no
why are vaccines not effective
organisms grown in lab differ from those in hose due to biofilm
what is host specificity mediated by
adherence and iron acquisition (trasnferrin)
culture and media
need sterile site or pure culture
chocolate agar
what do some species require to grow
CO2
is serology used, what is most common
not usually used
CTF most common
ELISA
treatment
antibiotics
AMR can occur (susceptibility testing)
