Micro. Flashcards
peptidoglycan - 2 functions
1) gives rigid support
2) protects against osmotic pressure
cell wall function
major surface antigen - induces TNF and IL-1
outer membrane (gram -) functions
site of endotoxin (LPS), major surface antigen
Lipid A induces TNF and IL-1
O polysaccharide is the antigen
plasma membrane function
site of oxidative and transport enzymes
what ribosomes do bacteria have vs. eukaryotes
bacteria: 30S + 50S = 70S
eukaryotes: 40S + 60S = 80S
periplasm - location and what it stores
location: between outer membrane and cytoplasmic membrane in gram - bacteria
Stores: hydrolytic enzymes such as beta-lactamases
what are pilus and fimbrae made of
glycoprotein
what is a flagellum made out of
protein
spore - what is it resistant to, what is it made out of
resistant to: dehydration, heat, chemicals
made out of: keratin-like coat, dipicolinic acid, peptidoglycan
capsule - function
protects against phagocytosis
quellung reaction
used to see if a bacterium is encapsulated
glycocalyx function
mediates adherence to surfaces, especially foreign surfaces (indwelling catheter)
either a capsule or a biofilm/slime - difficult to remove from surfaces
enzyme that crosslinks the peptide side chains in peptidoglycans
transpeptidase
bugs that do not gram stain well + reason why
These Microbes May Lack Real Color
Treponema: too thin to be visualized
Mycobacteria: high lipid content
Mycoplasma: no cell wall
Legionella: intracellular - branched chain fatty acids in cell wall do not stain well
Rickettsia: intracellular parasite
Chlamydia: intracellular parasite - lacks classic peptidoglycan because of low muramic acid
How to visualize treponema?
dark field microscopy
How to visualize legionella?
silver stain
What bugs can you visualize with Giemsa?
Certain Bugs Really Try My PaSHience
C: chlamydia B: borrelia R: Rickettsia T: trypanosomes --> t. cruzi P: plasmodium H: histoplasma
PAS (periodic acid schiff) stains what and what organisms can be visualized?
stains: glycogen and mucopolysaccharides
diagnose: Whipple disease - tropheryma whipplei
Ziehl Neelsen (carbol fushsin) helps visualize what organisms
Acid fast bacteria: nocordia, mycobacteria, protozoa (cryptosporidium oocyts)
What is the alternative to Ziehl Neelsen and how does it compare?
Auramine/rhodamine stain for screening
inexpensive, more sensitive, less specific
India ink can be used to visualize which organisms?
cryptococcus neoformans
mucicarmine stain
stains red- really just used for cryptococcus neoformans or mucin (some cancers produce mucin)
Silver stain is used to visualize which organisms?
fungi (pneumocystis), legionella, helicobacter pylori
H. influenzae requires what culture
Chocolate agar
N. gonorrhea/meningitis requires what culture
Thayer martin
B. pertussis requires what cultures
Bordet Gengou
Regan Lowe
C. diphtheria requires what culture
Tellurite agar, Loffler medium
M. tuberculosis requires what culture
Lowenstein-Jensen
M. pneumoniae requires what culture
Eaton agar
Lactose-fermenting enterics require what culture
MacConkey agar
E. coli requires what culture:
Eosin-methylene blue (EMB) agar
Legionella requires what culture
Charcoal yeast extract agar buffered with cysteine and iron
Fungi require what culture
Sabouraud agar
Chocolate agar contains what
Factors V (NAD+) and X (hematin)
Thayer Martin contains what
Very Typically Cultures Neisseria
Vancomycin, Trimethoprim, Colistin, Nystatin
Colistin inhibits what?
inhibits gram - except Neisseria
Bordet-Gengou agar contains what
potatoe
Regan Lowe medium contains what?
Charcoal, blood, and antibiotic
Eaton agar requires what?
cholesterol
MacConkey agar turns what color and why?
Fermentation produces acid, which causes colonies to turn pink
What colors do EMB agar colonies turn?
colonies have a green metallic sheen
Chocolate agar cultures what organisms?
h. influenze
Thayer Martin agar cultures what organisms?
Neisseria gonorrhea/meningitidis
Bordet Gengau agar cultures what organisms?
B. pertussis
Regan-Lowe medium cultures what organisms?
B. pertussis
Tellurite agar, Loffler medium cultures what organisms?
C. diphtheriae
Lowenstein Jensen agar cultures what organisms?
M tubercululosis
Eaton agar cultures what organisms?
M. pneuoniae
MacConkey agar cultures what organisms?
Lactose fermenting enterics
EMB agar cultures what organisms?
E. coli
Charcoal yeast extract agar buffered with cysteine and iron cultures what organisms?
Legionella
Sabuouraud agar cultures what organisms?
fungi
aerobic organisms:
Nagging Pests MustBreathe
Nocardia
Pseudomonas aeruginosa
MycoBacterium tuberculosis
Anaerobic bacteria lack what enzyme(s)
Catalase and/or superoxide dismutase - makes them susceptible to oxidative damage
Three general features of anaerobic bacteria:
1) foul smelling (short chain fatty acids)
2) difficult to culture
3) produce gas in tissue (CO2 and H2)
Where are anaerobes normal flora in the body?
GI tract
What antibiotic is resistant to anaerobes and why?
Aminoglycosides because they require O2 to enter the bacterial cell
What bacteria are anaerobes?
Frankly Can’t Breathe Air
Fusobacterium
Clostridium
Bacteroides
Actinomyces
Obligate intracellular bugs:
[stay inside when it is] Really COld and CHilly
Rickettsia
COxiella
CHlamydia
Why are obligate intracellular bugs obligate intracellular?
rely on host ATP
Facultative intracellular bugs:
Some Nasty Bugs May Live FacultativeLY
Salmonella Neisseria Brucella Mycobacterium Listeria Francisella Legionella Yersinia Pestis
Encapsulated organisms:
SHiNE SKiS
Salmonella typhi
Haemophlius influenzae type B
Neisseria meningitidis
E. coli
Strep pneumoniae
Klebsiella pneumoniae
group B Strep (agalactiae)
Urease postive organisms:
CHunk PUNKSS
Cryptococcus H pylori Proteus Ureaplasma Nocardia Klebsiella Staph epidermidis Staph saprophyticus
Catalase positive organisms:
Cats Need PLACESS
```
Catalase
Nocardia
Psuedomonas
Listeria
Aspergillus
Candida
E. coli
Staphylococci
Serratia
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Actinomyces israelli color
yellow sulfur granules - composed of filaments of bacteria
S. aureus pigment
yellow pigment
Pseudomonas aeruginosa pigment
blue green pigment
Serratia marcescens pigment
red pigment
Corynebacterium diphtheria toxin and MOA
diphtheria toxin
Inactivates EF2 via ADP ribosylation
Pseudomonas aeruginosa toxin and MOA
Exotoxin A
Inactivates EF2 via ADP ribosylation
Shigella toxin and MOA
Shiga-toxin
Inactivates 60S ribosome by removing adenine from rRNA (inhibits protein synth)
EHEC toxin and MOA
Shiga-like toxin (SLT) - inactivates 60S ribosome by removing adenine from rRNA (inhibits protein synth)
ETEC toxin and MOA
Heat labile toxin & heat stable toxin
HLT: overactivates adenylate cyclase, increasing cAMP, increasing Cl- secretion in gut and water efflux
HST: overactivates guanylate cyclase, increasing cGMP, decreasing reabsoprtion of NACL and H20 in gut
Bacillus anthracis toxin and MOA
edema toxin
mimics adenylate cyclase enzyme, increasing cAMP
Vibrio cholera toxin and MOA
cholera toxin
Overactivates adenylate cyclase (increasing cAMP) by permanently activating Gs - increases Cl- secretion in gut and H20 efflux
Bordatella pertussis toxin and MOA
pertussis toxin
Overactivates adenylate cyclase (increasing cAMP) by disabling Gi = impairing phagocytosis to permit survival of microbe
clostridium tetani toxin and MOA
Tetanospasmin
Protease that cleaves SNARE - prevents release of inhibitory neurotransmitters (GABA and glycine) from Renshaw cells in spinal cord
clostridium botulinum toxin and MOA
botulinum toxin
protease that cleaves SNARE - prevents release of stimulatory Ach neurotransmitter that signals at NMJ
clostridium perfringens toxin and MOA
alpha toxin
phosphlipase (lecithinase) that degrades tissue and cell membranes
Strep pyogenes toxin and MOA
Streptolysin O
Protein that degrades cell membranes
staph aureus toxin and MOA
Toxic shock syndrome toxin 1
Binds to MHC II and TCR outsie of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN gamma, and TNF-alpha
strep pyogenes superantigen toxin and MOA
exotoxin A
Binds to MHC II and TCR outsie of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN gamma, and TNF-alpha
What do spores have in their core?
dipicolinic acid
How do you kill spores
must autoclave to potentially kills pores (steam at 121 degrees for 15 minutes)