Microm 442 Ch 1-4 Flashcards
Ch 1-4
Francis Bacon
observations power accurate conclusions
Hooke & van Leeuwenhoek
single-lensed microscopes
light microscope
0.2µm
electron micriscope
0.003µm and beyond
x-ray crystallography
0.0001µm
Edward Jenners
cowpox vaccination against smallpox
florence nightingale
hygiene = avoid infection
Pasteur & Koch
microbes as causative agents of disease
Hans Christian Gram
Gram stain (crystal violet used)
paul elrich
“606” salvarsan or sarsphenamine
alexander fleming
penicillin
ernst chain and howard florey
purification/production of penicillin
gerhard domagk
sulfonamides
avery, macleod, mccarty
dna is a transforming principle
sanger
protein sequencing
watson, crick, rosalind franklin
dna structure
rich roberts
restriction enzymes
herb boyer, stanley cohen
recombinant dna
kary mullis
PCR
prokaryotes have no
sterols
Gm- cell
LPS, outer membrane, thin layer of peptidoglycan, s-layer and cytoplasmic membrane
Gm+ cell
thick layer of peptidogylcan, cytoplasmic membrane and s-layer
spheres
0.2-2µm
rods
0.2-2µm wide by 1-10µm long
higher order arrangements
biofilms, microbiota (communities)
90% dry mass composed of macromolecules also found in eukaryotes
55% protein, 20% RNA, 3% DNA, 5% carbohydrate, 6% phosopolipid, the rest is UNIQUE
capsule/slime made of polysaccharide/polypeptide
GN, GP (also not found in some of either tho)
appendages, pilli (fimbriae), flagella
GN, GP (also not found in some of either tho)
outer membrane proteins, LPS, phospholipids
GN
peptidoglycan (murien, NAG, NAM, peptide side chains)
GN, GP
teichoic acids
GP
periplasm (proteins, oligosaccharides)
GN
cytoplasmic membrane
GN, GP, Mycoplasma
s-layer is in
some Gm+ but not all
lipid A of lPS
rapidly induces fever because recognized by the immune system
Gm+ do not have
potential space because no outer membrane(?)
transcriptional/translational coupling
can happen simultaneously because no true nucleus in bacteria
relationships with host
colonize, multiply, transmission
initially broader group narrowed by ability to maintain colonization; then same as age group of given environ
neonate
fetus is
micro-biologically sterile
important for keeping mutualistic bacteria in the right places and numbers for defense
normal functioning anatomy
staphlococcus epidermidis; other staphylococci; propionibacterium/cucibacterium; diphtheroids
skin
s.epidermidis; non-pathogenetic coynebacteria
conjunctiva
fibrial illness=
fever
streoptoccous mutains adhere to
teeth
10E08 orgs/mL
saliva
neisseria & moraxella
mouth
strict anaerobes and microaerophiliic organsisms associated with
gingival crevice
normally, small intestine and stomach
sparsely inhabited
bacterial enthodecrosis
bacteria from teeth to heart
90% anaerobes (bacteroides and fusobacterium)
10% facultative anaerobes (e.coli, enterobacteriaceae, enterococci, yeasts like candida)
colon
feces are about 25% bacteria by weight
colon
only recognizes human oligosaccharides -> co-evolution
bifidobacterium
helps reinforce barrier that maintains normal levels in GI tract
bifidobacterium
lacto-N-biosidase can degrade lacto-N-tetraose an abundant milk oligosaccharide (HMO)
LnbX
similar to skin, importantly includes staphylococcus aureus
nares
similar to mouth but 1. streptococcus pheumonia 2. Nisseria meningitidis 3. haemophilus influenzae
nasopharynx
protects larynx and below middle ear and sinuses
muociliary escalator
What external body part is part of the respiratory tract
ear
young children and people get more middle ear infections because
smaller
detection of sound
tympanic membrane
scanty microbiota from perineum in first 1 cm of urethra, sterile above this in health
urinary stract
before puberty/after menopause: mixed, non-specific from skin, colon, perineum
vagina
lactobacillius, anaerobic GNRs, GPC, Gardnerella, Mycoplasma, Ureaplama
child bearing years
Gardnerella, Mycoplasma, Ureaplama
can also be pathogenic in that space
is sterile but gets contaminated in bladder and onwards
urine
quantity, genetic attributes
opportunists
priming the immune system
beneficial effects
demonstrated by antibiotic treatment, contributes more to gene expression than you do
exclusionary effect
vitamin K (coagulation), digestion, malabsorption
nutritional
skin, cilia escalator, GI tract, etc.
barriers to infection
syn for diagnosis
Diacrisis
the determination of the nature of a disease
diagnosis
- history 2. physical exam 3. imaging 4. laboratory testing 5. treatment
diagnosis steps
apply specific interventions to a clearly define problem (best antibiotic usually the cheapest but can only use when certain)
tailor therapy
great imitators, inflammatory cell death by immune system looks like:
1. heart attack
2. stroke
3. cancer
4. ?
exclude non-infectious causes of symptoms
specimen collected thru a site containing normal microbiota
indirectly non-sterile
at a site with normal microbiota (nasalpharynx, oralpharynx)
non-sterile
will only find what you are looking for
have a great sample
gram stain, acid-fast stain
bright field
thin organisms (spirochetes) e.g. syphilis
dark field
very sensitive but artifacts can cause problems (antibody that recognizes pathogen unless pathogen is sticky)
fluorescence
uses excitation wavelength to refract light on organisms membrane, looking for specific structures
fluorescence
two types of fluorescent microscopy
direct, indirect
antigen fixed to slide + fluorescein-labeled antibody
direct fluorescence
antigen fixed to slide + fluorescein-labeled antiimmunoglobulin which creates an antigen-antiobdy complex
indirect fluorescence
some need high amount of nutrients to grow
nutrient media
want inhibition of certain pathogens
selective media
show physiological attributes of pathogen
indicator species
low oxygen
microaerophillic
- 9 log amplification: 1 bacteria forms a colony on a plate
- ability to isolate single cells on a plate: singly colony isolation
conventional identifications two tools
catalase: h2o2->o2 + h2o
urease: (nh2)2c=o -> nh3 + co2
coagulase: fibrinogen -> fibrin clot
biochemical characteristics
pathogen->catalse breaks down hydrogen peroxide->kills microbes->minor wound care
nucleic acid sequences/functional genomics
genes in chromosome let them cause disease
functional genomics
produce: catalase, coagulase, etc.
enzymatic function
- gross phenotype
- biochemical characteristics
- antigenic structures e.g. streptococcal polysaccharide
- toxin production
- nucleic acid sequences, functional genomics
- flow of information: dna, rna, enzymatic functions, structure
identifying pathogens
identification of host immunoglobulins specifically recognizing antigens from pathogenic organisms
serological detection of disease
i) measured by titer
ii) acute disease: antibody titer increases
iii) significance: acute disease vs convalescent, 4-fold increase in titer, igM/igG primary vs secondary
hummoral immune response in a immunocompetent host
IgM
primary infection
IgG
secondary infection
more IgG formed
secondary response/second exposure
good for pathogen difficult/impossible to cultivate
pathogen specific nucleic acid sequences
can a dead pathogen cause an infectious disease
disease yes, infectious disease no
-false-positive due to contamination
-contamination obscuring diagnosis
-limited ability to assess properties of pathogen
molecular detection drawbacks
get a predominant product (dye terminator sequencing)
sanger sequencing
-accuracy for ID-> taxonomy -> families similar in pathogenic traits
-phylogeny (divergence of genetics indicates relation, RNA used)
-accurate molecular chronometer or “evolutionary clock”
sequencing platform requirements
primers for variable regions
specific id
competent host
primary pathogen
compromised host
1. loss of specific defenses
2. loss on non-specific defenses
opportunistic pathogen
occurs after colonization when multiplication is sufficient to cause damage/alter host
infection
rubor, tumor, calor, dolor, loss of function
inflammation
red
rubor
warmth
calor
pain
dolor
how much pathogen needed to establish infection
infectious dose
proximity, time, presence/absence of barriers
exposure parameters
bacterial replication - bacterial death
net replication
replication>death
+
replication<death
-
response time faster, going negative is good
vaccinated individual
successful colonization without sufficient multiplication
carrier/latent
quantitative measure of pathogenticity or likelihood of causing disease
virulence
quantitative measure of pathogens ability to infect another susceptible host
infectivity
ppl infected/# susceptible and exposed
attack rate (infectivity)
- adherence -> pili e.g. E.coli
- motility -> flagella and chemotaxis e.g. enteric organisms
- survival of fitness in environment outside of host
colonization
- nutrition
- avoiding host immune sureveillance
multiply
-iron
-siderophores -> enteric organisms
-lactoferrin/transferrin receptors= N. gonnorrhoeae
nutrition
salmonella & MTB
modify phagoloysosome
toxoplasma
block phagolysosome fusion
listeria, shigella
leaving phagolysosome (into cytoplasm)
- inhibit phagocytosis
- block complement mediated lysis
- antigenic variation
extracellular
-capsules: s. pneumoniae
-IgA proteases: H. influenzae
-bind host proteins: fibirongen by M-protein of group A strep
inhibit phagocytosis
functions as dimer but cleaved by protease
IgA protease
s. typhimurium LPS -> decrease membrane potential by punching a hole in it
block complement mediated lysis
borrelia-> antigens on surface constantly changing
antigenic variation
pertussis toxin alters lymphocyte function
exotoxin
can overstimulate host regulating in DIC (disseminated intravascular coagulation)
endotoxin
polyclonal t-cell proliferation
superantigens
-classical A B subunit toxins e.g. PT, DT, CT
-A catalytic sub-unit; ADP ribosylates G-proteins
-B membrane-binding subunits
-B binds to A and lets A into cytoplasm
exotoxins
hemolysins, large number repeats looks like compliment structures
RTX (repeats in toxin)
-GN -> LPS
-GP -> lipoteichoic acids
-Both -> peptidoglycan
endotoxins (part of microbes)
only expressed in the host
expression of virulent determinants
i) diphtheria toxin (A+B subunit)
ii) plasmids -> yersinia adhesins, invasins, and effectors
iii) transposons -> drug resistance
mobile virulence determinants
diphtheria toxin
A+B subunit
-S: sensor of environmental stimuli
-R: response regulator, regulates protein fxn/gene expression
2 component regulatory system (R/S)
-temperature
-ionic conditions (iron, calcium)
-oxygen concentrations
-pH
altered expression of determinants in response
