basis of bacteriology part 1 Flashcards
what does the gram stain show with bacteria ?
gram positive bacteria are purple
gram negative bacteria are pink
what feature in bacteria allow for the absorbance of thee gram stain ?
peptidoglycan
gram positive have lots of peptidoglycan
gram negative dont
why doesn’t mycoplasma take up the gram stain ?
no cell wall
why doesn’t mycobacterium take up the gram stain ?
cell wall has mycolic aid and not peptidoglycans
why doesn’t chlamydia take up the gram stain ?
the cell wall has mycolic acid
what is the main trigger for the immune system in gram negative bacteria vs gram positive bacteria ?
gram negative have an outer polysaccharide layer called an LPS
gram positive have LTA
what are the different structures in LPS ?
polysaccharide
Lipid A
O Antigen Antibody
why is a patient with a gram negative bacterial infection so sick ?
due to the presence of lipid A
which is a type of LPS
what is the function of thee capsule ?
protects against phagocytosis and helps tttachh to host cells
what is the capsule usually made out of and what are the exceptions ?
usually made out of polysaccharides and water except
bacillus anthrax where thee capsule is made ot of a protein
what test can be used for the detection off encapsulated bacteria ?
quellung reaction
what is the immune response to encapsulated bacteria ?
1- no phagocytosis
so there is stimulation of B cells which secrete antibodies
2- activates thee complement pathway
formation of MAC and cell death
form of C3b
what condition is associated with higher risk of infection of encapsulated bacteria ?
asplenia
what are the conjugated vaccines ?
neisseria meningitides
strep pneumonia
H.influenza type B
what structure is similar to the capsule and what is its function ?
glycocalyx
creates a biofilm
sticks to catheters and associated with staph epidermis
what are the two different types of pilli ?
ordinary pilli - allow adherence to surface E.coli
sex pilli - neisseria gonorrhea
what is the dormant version of bacteria ?
spores
why are spores so resistant to treatment ?
has a coat - keratin like
cortex - peptidoglycan
dipicolonic acid - heat resistant
where do we find the b lactamase enzyme ?
in the periplasm
lipoteichoic acid is found in what type of bacteria ?
in gram positive
