L1. Classification by structure, replication, metabolism Flashcards
What are bacterial fimbriae used for?
adhesion
what are mesosomes used for?
areas in the cell membrane of bacteria that fold inward - play an important role in cellular respiration
Which bacterial species does not have a cell wall as the outermost layer?
mycoplasma (b/w capsule and cytoplasmic membrane)
what are other names for peptidoglycan? (2)
murein or mucopeptide
what are the components of the bacterial peptidoglycan layer? (5)
diaminopimelic acid
muramic acid (ex NAM)
techoic acid
pentaglycine crossbridge
tetrapeptide sidechain
what is the function of diaminopimelic acid?
forms peptide linkages in bacterial peptidoglycan
what is the function of muramic acid?
structural component of peptidoglycan (NAM and NAG)
what is the function of techoic acid?
to provide rigidity to the cell-wall by attracting cations such as magnesium and sodium
go through PG (perpendicular to it)
what is the function of the pentaglycine crossbridge?
structural component that “cross” with muramic acid (NAM and NAG)
this is the component inhibited by beta lactam antibiotics!
what is the function of tetrapeptide sidechain?
contains: L alanine D glutamic acid L lysine D alanine helps add layers within PG (how i see it)
where does lysozyme act on peptidoglycan?
beta 1 - 4 linkages b/w NAG and NAM
what are the stain colours for gram pos/neg
pos - purple
neg - pink
does the cytoplasmic membrane of bacteria contain cholesterol? :)
no :( relax
what are the major differences b/w gram pos and gram neg cell wall?
gram negative has unique outer cell membrane
peptidoglycan is thin and within “periplasmic space”
instead of techoic acid, has murein lipoprotein (extends from PG to outer cell membrane)
whats unique about the outermost cell layer of gram neg cell wall?
its existence
outermost portion contains LPS!
Whats the structure of LPS?
O polysacc: outer carbohydrate chain (vary 1 - 50)
core polysacc: centre part
Lipid A: phosphorylated glucosamine disacc
whats the most toxic part of LPS?
Lipid A aka the gram negative endotoxin
what is the function of LPS?
blocks passage of substances to peptidoglycan layer
in humans can cause septic shock
what does pleomorphic mean?
bacteria lacking a distinct shape
how do bacteria cells reproduce?
binary fission (literally divide into two)
what are endospores?
dormant, tough, non reproductive structure produced by a small number of bacteria
what is sporulation?
process of forming an endospore
occurs when environment is unfavourable
what are the two most important bacteria that form endospores? why?
bacillus and clostridium
why? because important PATHOGENS
what are the stages of endospore germination?
- activation: can only be activated a few days after being formed
- initiation: autolysin degrades cortex peptidoglycan; calcium dipicolinate is released
- outgrowth: emergence of new vegetative cell consisting of spore protoplast w/ surrounding wall
what is calcium dipicolinate (2)?
protects DNA of spore from heat denaturation (inserts itself in b/w DNA bases)
dehydrates the spore
What are the seven spore forming bacteria?
Bacillus anthracis and cereus
Clostridium botulinum, perfringens, difficile and tetani
what does bacillus cereus cause?
food poisoning
How do you stain for an endospore to be visible (2)?
Schaeffer - Fulton method:
- malachite green (primary stain - endospores)
- safranin
(counter stain - vegetative)
what is the only bacteria with a capsule made of protein?
bacillus anthracis
How do you stain for a capsule?
negative staining: stains the background
what is the quelling reaction?
antibody reaction w/ capsule - capsule swells
What are the nine encapsulated bacteria?
Yes Even Some Pretty Nasty Killers Have Shiny Bodies
yersinia pestis E coli strep pneumonia pseudomonas aeruginosa Neisseria meningitides Klebseilla pneumonia H. influenza Salmonella typhi Bacillus anthracic
What are the different types of flagella (4)?
Monotrichous: single polar flagellum
lophotrichous: 2 or more flagella at one end
amphitrichous: 1 or more flagella on both ends
peritrichous: flagella all over
How is flagella stained (2)?
first apply a mordant (tannic acid or potassium alum)
then stained w/ pararosaniline or basic fuschin
Which class of bacteria are mesosomes more prominent in?
gram positive bacteria
fimbriae vs pilli
pilli are usually longer and are also involved in transfer of dna during conjugation
endotoxins vs exotoxins
endotoxins - usually by gram negative bacteria; structural components
exotoxins: usually by gram positive bacteria, proteins
What are the 7 classic gram positive bugs that cause disease in humans?
cocci:
strep
entero
staph
bacilli: bacillus clostridum corynebacterium listeria
what are the 2 groups of gram negative cocci?
diplococci:
neisseria and moraxella
What is an oxidase test used for?
blue - positive
yellow - negative
detects the presence of cytochrome oxidase -> used in ETC!
which gram positive bacteria is identified with acid fast stain?
mycobacteria
what is the first line lab test used to identify bacteria?
gram stain
what are the 11 bacteria that are not stained well by gram stain?
These Little Microbes May Unfortunately Lack Real Colour But Are Everywhere
Treponema, Leptospira (too thin to be seen)
Mycobacteria (high lipid content in cell wall)
Ureaplasma, Mycoplasma (no cell wall)
Legionella, Rickettsia, Chlamydia, Bartonella, Anaplasma, Ehrlichia
why is chlamydia known to be lacking “classic peptidoglycan”?
when it is intracellular, muramic acid is reduced
what are some of the other stains available?
india ink
fluorescent antibody
silver stain
albert stain
what is silver stain used for?
Fun legions are hyped
Fungi, Legionella, and H. pylori
what is albert stain used for?
granules - red to violet
rest of bacteria - blue/green
stains “volutin” granules in C diphtheria
What is india ink used to identify?
cryptococcus neoformans
What is a common acid fast stain?
zeihl neelsen stain
carbol fuschin - primary stain
methylene blue - secondary stain (for non acid fast bacteria)
what are the four acid fast bacteria?
mycobacterium tuberculosis
mycobacterium leprae
nocardia asteroids
actinomycetes
what are voluntin granules?
food stores found in bacteria
what is albert stain made of (2) ?
toluidine blue and malachite green
what is thayer martin agar used for?
selective growth of Neisseria (gonnorhoeae and meningitides)
what is colistin used for?
inhibits most gram neg bacteria other than Neisseria
What is vancomycin used for?
selective media tha inhibits most gram pos bacteria
what is nystatin used for?
inhibits yeast
what is modiefied thayer martin agar used for?
contains added trimethoprim to inhibit proteus!
What is McConkey agar used for?
to differentiate between lactose and non lactose fermenters
lactose fermenter - turns pink
what is CHROMagar used for?
to identify enterococcus faecalis (turns green)
what is E coli grown on?
blood agar
what is serratia grown on?
chocolate agar
What is chocolate agar used for (5)?
to grow h. influenza, serratia, neisseria species (g and m) and haemophillus
What is regan lowe medium used for?
to grow pertussis
contains charcoal, blood and antibiotic + potato extract
What is eaton agar used for?
Mycoplasma pneumoniae
gram neg
What is EMB (eosin methylene blue) agar used for?
E coli!
produces “metallic sheen” colour
What is bordet gengou agar used for?
pertusis
what is sabouraud agar used for (2)? what does it contain?
fungi filamentous bacteria like nocardia!
contains peptones!
what is tellurite agar used for?
Diptheria
what is mannitol salt agar used for (2)?
used to isolate Staph Aureus
(yellow)
serratia would be red
what is charcoal yeast extract buffered w/ cysteine and iron used for (4)?
Bruce Francis and the Legion of Pastors
Brucella, francisella, legionella, pasteurella
what are the 4 aerobic bacteria?
Nagging Pests Must Breathe
Nocardia, pseudomonas, mycobacterium TB, bordetella pertussis
what are the 4 obligate anaerobes?
clostridium, bacteriodes, fusobacterium and actinomyces israelii
why can obligate anaerobes not survive in the presence of O2 (3)?
lack catalase
susceptible to oxidative damage
foul smelling and produce gas (CO2 and H2)
What are the 4 facultative anaerobes?
strep, staph and enteric gram positive bacteria as well as E coli
what are the urease positive organisms (5 + 3)?
PUNCH
proteus, ureaplasma urealyticum, Nocardi, cryptococcus, H. pylori
KISS
klebsiella, S saprophyticus and S epidermidis
how does a urea breath test work?
patients ingest labelled urea
if urease positive organisms are present, labelled CO2 will be detected (scintillation counter or special spectrometer)
what are the 3 obligate intracellular bacteria?
Really Chilly and Cold
Rickettsia, Chlamydia and Coxiella
what are the 4 biofilm producing bacteria?
Epic Virus Pink Homo
S. epidermidis, Viridans, Pseudomonas aeruginosa and H. influenza
where does S. epidermidis form biofilms (2)?
catheter and prosthetic devices
Where do viridans form biofilms?
dental plaques
Where does Pseudomonas form biofilms (2)?
respiratory infections and keratitis (contact lens associated)
Where does H. influenza form biofilms?
Otitis media (ear)
what is the temperature most pathogenic bacteria grow at?
37 deg
what bacteria grows well at 42 deg?
campylobacter
what bacteria grows at low temperatures (0 - 4 deg)?
listeria monocytogenes
food poisoning
what pathogenic protein is NOT destroyed by autoclave?
prion proteins
what can ethylene oxide not work against?
spores
what is hydrogen peroxide effective against?
all microorganisms including spores!
what is pasteurization NOT effective against?
heat resistant spores
did not include infection control!
x
