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Basic bacteriology, Endotoxin, basic bacteriology, Bacterial structure,…
Basic bacteriology
Endotoxin
Corynebacterium diphtheriae
diphtheria toxin
inactivate EF-2
pharyngitis(咽頭炎), lymphadenopathy
Pseudomonas aeruginosa
Exotoxin Aª
inactivate EF-2
host cell death
Shigella spp.
Shiga toxin
inactivate 60S ribosome
GI damage→dysentery(赤痢), hemolytic uremic syndrome;HUS(溶血性尿毒症候群)
Enterohemorrhagic E.coli
Shiga-like toxin
inactivate 60S ribosome
HUS, does not invade host cell
Enterotoxigenic E.coli
heat-labile toxin(LT), heat-stable toxin(ST)
↑cAMP→↑CL⁻ in gut, ↑cGMP→↓resorption of NaCl and H₂O in gut
water diarrhea
Bacillus anthracis
Edema toxin
↑cAMP
black eschar(黒い焼傷)
Vibrio cholerae
cholera toxin
activate Gs→↑Cl⁻ secretion in gut
rice-water diarrhea
Bordetella pertussis(百日咳)
pertussis toxin
disabling Gi→↑cAMP
Whooping cough : child cougn
Clostridium tetani
tetanospasmin
protease that cleave SNARE, aset of protein required for neurotransmitter release via vesicular fusion(小胞融合)
prevent inhibitory neurotransmitter(GABA)→spastic paralysis(痙攣性まひ), risus sardonicus(痙笑), trismus(開口障害)
Clostridium botulinum
botulinum toxin
similar to tetanospasmin
prevent stimulatory signal at neuromuscular junction(ACh)→flaccid paralysis(弛緩性麻痺)
Clostridium perfringes(ウェルシュ菌)
alpha toxin
phospholipase degrade tissue and cell membrane
↓phospholipid→myonecrosis, hemolysis
Streptococcus pyogenes(化膿レンサ球菌)
streptolysin O
degrade cell membrane
β-hemolysis, ASO diagnose rheumatic fever (suggest streptococci infection, PSGN)
Staphylococcus aureus
toxic shock syndrome toxin(TSST-1)
release of cytokine→shock
Streptococcus pyogenes
erythrogenic exotoxin A
release of cytokine→shock
basic bacteriology
Encapsulated bacteria
capsule serve as antiphagocytic virulence factor
use as antigen in vaccines
eg. Pneumococcal, H.influenzae, Meningococcal
eg. P aeruginosa, S. pneumoniae, H influenzae, N.meningitis, E.coli, Salmonella, K.pneumoniae, groupB streptococcus
asplenics have ↓opsonization and ↑risk for severe infection
Pigment-producing
Actinomyces israelii(放線菌症) : yellow
S.aureus : yellow
P.aeruginosa : blue-green
Serratia marcescens : red
Catalase-positive
degrades H₂O₂ into H₂O and bubbles of O₂
CGD patient has reccurent infection
eg. Nocardia, Pseudomanas, Listeria, Aspergillus, Candida, E.coli, Staphylococci, Serratia, B.cepacia, H.pylori
virulence factor
ProteinA : bind Fc region of IgG, prevent opsonization and phagocytosis(eg. S.aureus)
IgA protease : cleave IgA (eg. S.pneumoniae, H.influenzae, Neisseria
M protein : help prevent phagocytosis (eg. group A streptococci)
anaerobes
eg. Clostridium, Bacteoides, Fusobacterium, Actinomyces
no catalase and/or superoxide dismutase
facultative anaerobes(通性嫌気性)
can use O₂ and use fermentation
eg. Streptococci, Staphylococci
intracellular bugs
obligate intracellular(偏性細胞内寄生体)
別の細胞内で増殖, rely on host ATP
eg. Rickettsia, Chlamydia, Coxiella
facultative intracellular
eg. Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
Urease-positive
urea to ammonia and CO₂→↑pH
eg. Proteus, Cryptococcus, H.pylori, Ureaplasma, Nocardia, Klebsiella, S.epidermidis(表皮ブドウ球菌), S.saprophyticus
aerobes
eg.Nocardia, P.aeruginosa, M.tuberculosis
biofilm-producing
S.epidermidis, S.mutans, S.sanguinis, P.aeruginosa, H.influenzae (unencapsulated)
type Ⅲ secretion system
"injectisome", needle-like protein appendage help delivery of toxin to host cell (eg. Pseudomonas, Salmonella, Shigella, E.coli)
Bacterial structure
stains
gram stain
thick peptidoglycan layer retain crystal violet dye (gram+), thin peptidoglycan layer turn red or pink (gram-)
not stained : Treponema, Leptospira, Mycobacteria, Mycoplasma, Ureaplasma, Legionella, Rickettsia, Chlamydia, Bartonella, Anaplasma, Ehrlichia
Giemsa staion
Rickettia, Chlamydia, Trypanosomes, Plasmodium, Borrelia
PAS stain
stain glycogen (Whipple disease; Tropheryma whipplei)
Ziehl-Neelsen stain
acid-fast bacteria (eg. Mycobacteria, Nocardia), protozoa
India ink stain(墨汁染色)
Cryptococcus neoformans
silver stain
fungi, Legionella, H.pylori
fluorescent antibody stain
identify many bacteria and viruses (eg. syphilis)
cell envelope
capsule : organized, discrete polysaccharide layer, protect
glycocalyx : loose network of polysaccharide : mediate adherence to surface
outer membrane(外膜)
outer leaflet : contain endotoxin(LPS/LOS)(lipidA: induce TNF and IL-1, antigenic O polysaccharide component)
embedded protein: porins and other outer membrane proteins(OMPs)
inner leaflet : phospholipids
gram- only
periplasm : between cytoplasmic membrane and outer membrane in gram- bacteria : including hydrolytic enzyme
cell wall : peptidoglycan is a sugar backbone with peptide side chain cross-linked by transpeptidase : net-like structure
cytoplasmic membrane : phospholipid bilayer sac with embedded protein and other enzyme, lipoteichoic acid extend from membrane to exterior (gram+) : PBPs involved in cell wall synthesis
taxonomy
Spherical(coccus)
Rod(bacillus)
Branching filamentous(糸状菌): eg. actinomyces, nocardia
pleomorphic(多形菌) : no cell wall
spiral
growth media
selective media: growth of particular organism
indicator media: color change in response to metabolism of organism
special culture
H.influenzae : chocolate agar
Neisseria : Thayer-Martin agar(Vancomycin, Trimethoprim, Colistin, Nystain)
B.pertussis(百日咳) : Bordet-Gengou agar, Regan-Lowe agar
C.diphtheriae : Tellurite agar, Loffler medium
M.tuberculosis : Lowenstein-Jensen agar
M.pneumoniae : Eaton agar
Lactose-fermenting enterics(乳頭発酵性腸内細菌) : MacConkey agar
E.coli : Eosin-methylene blue agar
Legionella : charcoal yeast extract agar
Fungi : Sabouraud agar
sppendages(付属器)
flagellum : protein, motility
pilus/fimbria : glycoprotein, adherence, sex pilus
specialized structure
spore : keratin-like coat; peptidoglycan, DNA, Gram+ only, resist dehydration, heat, chemical
Endotoxin
macrophage activation
TNF-α
fever and hypotension
nitric oxide
hypotension
IL-1, IL-6
fever
complement
C3a
histamin release
hypotension and edema
C5a
neutrophil chemotaxis
tissue factor activation
coagulation cascade
DIC
outer membrane of gram - cell
O antigen + core polysaccharide + lipidA
macrophage activation, complement activation, tissue factor activation
Bacterial genetics
Transformation
competent bacteria can import naked DNA
eg. S. pneumoniae, H.influenzae, Neisseria
deoxyribonuclease degrades naked DNA
Conjugation
F⁺×F⁻
F⁺ have plasmid and sex pilus, F⁻ don't have
across the conjugal bridge
Hfr×F⁻
plasmid is incorporated into bacterial chromosomal DNA
then, transfer
high frequency recombination (Hfr) cell
transduction
Generalized
packaging error
DNA cleavage and form phage capsid→release→transfer gene via phage
lytic phage(溶菌ファージ)
Specialized
excision event
viral DNA incorporate in bacterial DNA via lysogenic phage→form phage→release→to other host cell via phage
lysogenic phage(溶原性ファージ)
eg. A strep erythrogenic toxin(発赤毒素), botulinum toxin, cholera toxin, diphtheria toxin, shiga toxin
Transposition
can jump (transfer gene from plasmid to chromosome and vice versa)
importent for antibiotic resistant bacteria
basic bacteriology
Spore-forming
highly resistant to heat and chemicals
core contains dipicolinic acid
must autoclave to kill
eg. Bacillus, Clostridium
Exotoxin vs Endotoxin
Exotoxin
secreted from cell
polypeptide
high adverse effect
toxoid use as vaccine
heat unstable (except for heat stable toxin from E.coli)
eg. tetanus, botulism, diphtheria
endotoxin
outer cell membrane of gram - cell
lipid A of LPS
low effect
fever, shock, DIC
induce TNF, IL-1, IL-6
stable at 100℃ for 1 hr
sepsis