Microbiology Flashcards
chemoheteroptrophs are
bacteria who use glucose as their carbon source
all pathogenic bacteria are ________trophs
chemoheteroptrophs
catalase
degrades peroxides into water and oxcygen
peroxidase
degrades peroxide using a reducing agent
all pathogenic bacteria are _____philes
mesophiles - grow best in T 25-40
Mannitol salt agar
Used to isolate pathogenic staph
what does mannitol salt sugar contain (3 things)
NaCl to select for bacteria that tolerate high nacl [ ]
Mannitol: carbohydrate source –> when mannitol is fermented it makes acid, turns agar yellow
phenol red: red at neutral pH, yellow in acidic, pink in basic
MacConkey Agar is used to differentiate
Used to isolate and differentiate members of enterobacteriacae (selects for gram -)
what are the components of MacConey Agar (4)
Lactose - carbohydrate source.
fermentation results in acid production and absoprtion of red –> pink/red colonies
Bile salt - inhibit growth of gram + bacteria
Neutral Red - below 6.8 is red, above 6.8 is colorless
Crysal violet - inhibits game +
Blood agar is used to
determine the ability of bacteria to hemolyse RBCs
what is in blood agar
5% sheep blood provudes RBCs for hemolysis
green or red color around colonies in blood agar
alpha hemolysis aka partial hemolysis od RBCs
clearing of medium around colonies on blood agar
beta hemolysis complete destruction of RBCs
chocolate agar
used for cultivation of fastidious organisms
what factors are in chocolate agar (2)
Factor X - hemin and Factor V which are important growth factors
what occurs in group translocation
combines transport of a molecule with the modification of that molecule (such as being changed by phosphorylation) which traps it inside the cell and cannot be transported out
what is a siderophore
it is secreted by pathogenic bacteria that will uptake iron fromthe body. they bind Fe3+ and transfer it across the bacterial membrane
most baceria use what kind of metabolic process?
Glycolysis
what kind of bacteria usually utilize enter-doudoroff pathways
gram -
This is an alternative mechanism of breaking glucose into 2 pyruvates
phenols are effective against
gram + bacteria and enveoped viruses
phenols are not effective against
spores and non-enveloped viruses
anionic agents are effective against
gram + bacteira
what do phenolic compounds do?
these compounds are bactericidal (at low concentrations) by causing membrane leakage and irreversible inactivation of membrane functions (e.g. inactivating enzymes)
alcohol is not effective against
spores
how are heavy metals effective against bacteria?
altering the 3D-structure of bacterial proteins, which compromises protein function and survival of
how do orgnic solvent and detergents work
These agents disrupt the cell membranes by solubilizing the lipids
how do quats work
Binding of the positively-charged quat with the negatively-charged bacterial surface results in major membrane damage.
how do halogens work? (oxidizing agent)
oxidizing cellular molecules (e.g.enzymes), resulting in diminished function and survival
how does H202 work
xidizing bacterial enzymes, which interferes with bacterial metabolism and kills the bacteria.
how do alkylating agents work
attaching alkyl groups to bacterial proteins and DNA resulting in nonfunctional molecules and ultimate death of the bacteria.
nly cold chemical sterilizing agent recommended by the CDC for use on respiratory therapy equipment.
Glutaraldehyde
preferred method of heat sterilization
moist heat
The most efficient temperature/pressure to destroy microbes
121°C and 15 psi
Dry heat sterilizes by
denaturing bacterial proteins and exerting oxidative damage but takes longer to sterilize in comparison to moist heat
main method of dryheat
Oven sterilization
kills spores, and can sterilize surgical gowns and rubber catheters
gamma radiation
dry heat is best used for
powders and sharps
gamma radiaion works by
forming free radicals –> disrupt DNA bonds, –> inhibition of bacterial division –> cell death
dry heat is best used for
plastic ware
what is the definition of host nutritional immuniyy
its when a host becomes infected and tries to withold nutrients to prevent bacterial growth
the actue inflammatroy response is related to iron how?
IL6, part of the acute phase, will trigger release of hepcidin from the liver, which further sequesters Fe
what kind of toxin causes diarrhea?
enterotoxins
secretion systems are found in what kind of bacteria
gram negative
type III secretion systems
uses a flagella-like appendage as an injection needle
type Iv secretion system
injecting proteins using a pilus like appandage as injection needle
what does RecA do?
RecA assists in the recombination process of transformation where DNa is realeased into the environment by dead cells and it is taken up by a live cell and recombined into its genome
bacterial gene expression is most often regulated at the point of
transcription
what is generalized transduction
phage breaks apart all of the DNA and it gets mixed up and randomly put into phage capsules. Some of them will have bacterial DNA and some will have phage DNA
what is specialized transudction
it is when a phage itnegrates with a host and then when induces pops out to make phage. when it pops out it will take with it adjacent parts of the bacterial genome.
specialized transduction is the same as
lysogenic cycle
two important toxins that are on specialize dphage
diptheria and cholera
gyrase is inhibited by what type of antibiotics?
cipro / quinilone
what is nucelotide excision repair
how you repair thyamine dimers from UV damage
what drugs block gyrase?
quinilones
what are the most common spontaneous mutations from
the loss of the nucelobase aka depurination
ionizing radiation, including UV, causes ________ cross linking
pyrimidine
disease that is deficient in nucelotide excision repair?
Xeroderma Pigmentosa
what bacteria is found on every body site with normal microbiota
aerobic gram negativve cocci and aerobic diptheroids
staphylococci and dipheroids
what kind of bacteria colonizes the mouth
alphahemolytic streptococci and obligate anaerobes
are there normal microbiota in the trachea?
no
in the colon the type of bacteria is mostly
anaerobic
what can colonize the stomach
helicobacter pylori
why is the pH of the vagina low?
because of the matabolism of glycoen
WHAT DOES SOD DO
it converts superoxide to hydrogen peroxide
in what temps do mesophiles grow best in
temps from 25-40
I have a pthologic staph and want to grow it. What agar do I use?
Mannitol salt sugar
colors of phenol red in
neutral
basic
acidic
red in neutral
pink in basic
yellow in acidic
enter bacteriacidae ferment what
lactose
in the macConkey Agar, what color is produced with and without fermentation of lactose
with fermentation –> acid production –> absorption of neutral Red —> red/pink colonies
wihtout fermentation –> colorless
what factors select for gram negative bacteria in the MacConkey agar
the crystal biolet and bile salts
what is the reason that a baceria will use the glycoxylate cycle
to utilize fat and the products of the process can lead to glucose production and AA synstheiss
how do detergents work
they disrupt the cell membrne –> leakage
anionic agents
decrease the ability of bacteria to bind to a surface
anionic agents are used to clear
skin and clothing
Heavy metals are used to trat what isease
silver sulfadiazine is used to treat topical burns
how do halogens work?
they oxidize cellular molecules
how do alkylating agents work?
they alkylate things and make them non functional
use ___ to disinfect dialysis machines
formaldehyde
on respiratory therapy equiptment use
glutaraldehyde
specification son moist heat?
121 c 15 psi
can moist heat kill spores?
yes
descrieb the two component regulatory system of a pathogen
first only when a certain environmental factor serves as the first signal, like temp, etc, a sensor kinase is activated and will phospohorylate a resposne regulator which will activate transcription of a certain gene
bacerial gene epression is controlled at th point of
transcrption
