lesson one and two Flashcards
universal ancestor
bacteria: g- and g+
universal ancestor
fungi, animals and us, amoeba
sizes of organisms from smallest to largest
prion and virus (visible with electron microscope), bacteria and fungi (visible with light microscope), parasites and mammals (visible with naked eye)
how many bacteria do we have in our body?
10 trillion bacteria in the gut
E. coli genus name
Escherichia
E. coli species name
Escherichia coli
E. coli subspecies
EHEC, EPEC, ETEC
bacterial naming order
- family
- genus
- species
- subspecies
bacteria naming
Genus, species
Cocci bacteria
staphylo, strepto, diplo
bacilli bacteria
diplo, strpto, cocco
spiral bacteria
vibrio, spirillum, spirochaete
differential stains
gram stain: divides most bacteria into two groups
acid fast stain: used for mycobacterium
gram stain
based on cell wall structure: amount of peotidogylcan (structural mesh) in the bacterial cell wall
gram stain procedure steps
- fix specimen on slide using heat
- add crystal violet: penetrates into peptidoglycan
- add iodine: washes away extra CV and stains inside cells
- differentiation step: acetone or alcohol to rinse away colour
- add saffron: counter stains gram - bacteria
gram + colour
purple/blue
gram - colour
pink/red after safranin is added
bacteriology
study of bacteria
virology
study of viruses
mycology
study of fungi and yeasts
parasitology
study of protozoa and metazoa
immunology
study of immunity
prokaryote
bacteria, small, unicellular organisms, no nuclear membrane, divide by binary fission
eukaryote
fungi, plant cells, human cells- genetic material collected in a nucleus with a surrounding nuclear membrane, divide with mitosis
gram + cell
contains thick peptidoglycan mesh, teichoic and lipoteichoic acids connected to peptidoglycan project outwards (gives a charge), no outer membrane, high susceptibility to penicillin
gram - cells
thin peptidoglycan layer (leaky cell wall), no teichoic acid, endotoxins (lipopolysaccharide/lipo-oligosaccharide), outer membrane is hydrophobic, low susceptibility to penicillin due to membrane presence
exceptions of gram stains
- mycobacterium: waxy cell wall
- mycoplasma: can’t retain cell wall
- chlamydia: too small
- rickettsia: intracellular
- treponema pallium: too slender
acid fast stain steps (ziehl neelson)
- add carbolfuchsin to smear
- heated
- add acid alcohol
- methylene blue: counter stain
neisseria meningitidis
- one cause of meningitis and sepsis
- gram -
- over 12 serotypes based on capsule carbohydrates
- 6 subtypes responsible for most of epidemics
- serotype b most common in developed nations
- only affects humans
meningitis
- inflammation of meninges in brain and spinal cord
- caused by microbes infecting cerebral spinal fluid
neisseria meningitidis transmission
droplet: coughs, sneezes, saliva up to 1m
neisseria meningitidis virulence
- attaches to epithelial cells in the throat
- invades and can go to the bloodstream
- contains endotoxin anchored in cell wall
- bacteria evade phagocytosis due to presence of capsule
neisseria meningitidis endotoxin
LOS- has lipid A as part of the molecule
- activates blood clotting, leads to DIC, hemorrhage and shock
meningococcal meningitis
- inflammation/infection of the meninges
- increased pressure to brain, influx of inflammatory cells to CSF
- death if untreated- if treated early has very good prognosis
meningococcal sepsis
- replication of bacteria in the bloodstream
- disseminated infection, can occur quickly, gram - sepsis, intravascular clotting
- death if untreated or if treated too late
meningitis symptoms
- headache
- stiff neck
- photosensitivity
- nausea
- sore throat
- petichiae
- coma, death
sepsis symptoms
- fever
- petichae/purpura
- shock
- hemorrhage
- internal organ meltdown
- death
neisseria meningitidis diagnosis
- aspirate CSF and/ or blood
- gram stain CSF
- culture and/or EIA or PCR
- serogroup for epidemiology
- ascertain susceptibility to antibiotics
- administer antibiotics (empirical) directly after taking culture specimens
neisseria meningitidis vaccine
- polysaccharide: effective against 4/15 types, 90% protection for 2-5 years, over 2 years only
- conjucated: for children under 2 and immunocomprimised individuals
- Type B vaccine: based on proteins in the cell wall not the capsule, 50-60% effective
neisseria meningitidis public health issues
- rapid ID of disease
- rapid ID of contacts
- prophylactic antibiotics
- vaccination of susceptible individuals
- health prevention information
- reportable disease