ICS - microbiolgy Flashcards
define pathogen
Pathogen
Organism that causes or is capable of causing disease
Define Commensal
Commensal
Organism which colonises the host but causes no disease in normal circumstances
Define Opportunist Pathogen
Opportunist Pathogen
Microbe that only causes disease if host defences are compromised
Define Virulence/Pathogenicity
Virulence/Pathogenicity
The degree to which a given organism is pathogenic
Define Asymptomatic carriage
Asymptomatic carriage
When a pathogen is carried harmlessly at a tissue site where it causes no disease
what areas are open to bacterial colonistation
muscoal surfaces
The GI tract, lungs, bladder, kidnyes, urter, urethrer, gallbladder
out of thses, teh lungs and bladder should try and be bacterial free
what dhape is a cocus
spherical
what shap is a bacillus
rod
what colour is gram positive
purple
what color is gram negaitve
pink
what is a curved rod shaped bacteria
vibrio
what is teh name for spiral rod
spirochaete (sounds like a type of pasta)
what stain is for microbactrium
ziehl-neelsen stain (acid fast stain)
what are the differences between gram positive and gram negative bacteria
gram posiitve bacteria have a thick peptidoglygan layer and gram negative dont, they have a large lipoplysachoride (also known as endotoxin) layer instead
what are the two types of bacterial toxins
ENDOTOXIN
Component of the outer membrane of bacteria, eg lipopolysaccharide in Gram negative bacteria
EXOTOXIN
Secreted proteins of Gram positive and Gram negative bacteria
what is a toxoid
Toxoid is a toxin treated (usually with formaldehyde) so that it loses its toxicity but retains its antigenicity
what are teh features of an exotoxin
protien, specific action, strong antingencity, produced by gram + and - bacteria, and convertable into a toxoid
what are teh features of endotoxins
liposaccoride, non specific, produced only by gram negative, not convertable to a toxoid
in what 3 modes can bacteria gain new genetic information
conjugation - via a sex pilus
transformation - sent over in a plasmid
transduction - via phage (infected by a virus)
what are the three ways a bacterias DNAs can change
base substitution, deletion, insertation
what is obligate intracellular bacteria
bacteria that cannot be grown on an artifical media, only in human cells and tissues
what are the three tpes of obligate intracellular bacteria
rickettsia, chlamydia, coxiella
what are teh cypes of bacteria that can grwo on an artifical media and have no cell wall
mollicutes
what are the cocci, gram negative, anaerobic bacteria
veillonella