Control of Microbial Population Flashcards
What is Ebers Papyrus
ancient document showing that people of ancient times were interested in how to treat diseases
document had tx for everything under the sun
Who is Paul Ehrlich
popularized the concept of magic bullet and also invented first tx for syphilis thereby initiating and naming the concept of chemotherapy
Who is Alexander Fleming
rediscovered penicillin
left petri dishes over night and noticed where fungi was growing, there was no bacteria
Who is Gerhard Domagk
red azo dyes –> compound will kill bacteria
prontonsil –> first antibiotic
what are the two methods of microbial control
physical and chemical
difference between physical and chemical methods for microbial control
physical: high temp (moist heat, pasteurization, dry heat), low temp, radiation, filtration, ethylene oxide gas
chemical: food preservatives, disinfectants, antiseptics, antibiotics, antifungals, antivirals
what roadmap does one use to go about deciding how to control microbes
what is it?
where is it?
what do you need to achieve?
Given streptococcus pyogenes as an example, use the roadmap to decide how you would go about controlling it
what is it? - streptococcus pyogenes
where is it? - living tissue (soft tissues of arms)
what do you need to achieve? - inhibition of growth
what microbe is most resistant to disinfectant and antiseptic agents
bacterial spores
what agent is successful at killing all the microbes which includes bacteria, virus, fungus, bacterial endospores, mycobacteria
formaldehyde and glutaraldehyde
difference between disinfectants and antiseptics
disinfectants tends to be used on hard surfaces while antiseptics can be used on living tissue like our skin and such
what agent can be used as both a disinfectant and an antiseptic
iodophors and alcohol
hence these two can be used on hard surfaces and living tissue
what microorganism is resistant to a lot of antiseptics and disinfectants
bacterial spores
what does it mean that bacterial spores have inherent resistance
endospore formation of a biofilm or a structural component of cell such as a waxy coating or outer membrane is where these microorganisms get their resistance from (AKA their resistance is not acquire rather it is innate)
what is meant by acquired resistance
microorganism building a resistance to an antiseptic or disinfectant agent due to multiple exposure (AKA it is not innate)
most resistant microorganisms
prions –> endospores –> mycobacteria
most susceptible microorganisms
enveloped virus –> gram pos bacteria —>large non enveloped viruses
NOT SURE HOW IMPO THIS IS but list the organisms from most resistant to most susceptible
prion –> endospores –> mycobacteria –> small non enveloped viruses –> fungal spores –> gram neg viruses –> vegetative fungi –> large non enveloped viruses –> gram pos bacteria –> enveloped viruses
PEMS-FGV-LGE
what does the number of microorganisms influence
tx type, duration, conc etc
what is the difference in time of inactivation in a bacteria vs. a bacterial endospore
it takes longer to kill those with an endospore and might take a higher conc of tx and even possibly a diff tx
give an example of a gram neg and a gram pos bacteria
gram neg - E. coli
gram pos - S. aureus
how does the MIC (minimum inhibitory concentration) differ in E. coli vs. S. aureus?
since E. coli is a gram neg bacteria, it takes higher MIC to inhibit its growth
what are some goals to achieve when it comes to microbes
- reducing microbial numbers to sanitary/acceptable levels
- slow down or inhibit microbial growth
- kill microorganism
- prevention vs. treatment
what is used to reduce microbial numbers to sanitary/acceptable levels
disinfectants
what is the process called when killing microorganisms
sterilization
what is difference in prevention vs. treatment
in prevention, antiseptics and disinfectants are used
in tx, therapeutic antibiotics are used
most effective liquid sterilant available
peracetic acid
why is peracetic acid considered so effective
kills endospores and viruses in 30 mins
kills bacteria and fungi in less than 5 mins
kills most microorganisms
what are some advantages of peracetic acid
no toxic residue
minimally affected by organic matter
what is peracetic acid actually used for
high level disinfection for eg heat or steam sensitive instruments for invasive procedures
what is the difference between an addition of a static and cidal compound during the log phase
static - keeps the microbes constant and they cannot replicate anymore
cidal - actually kills the microorganisms
difference in bacteriostatic and bacteriocidal in term of onset, requiring functional immune system, used in immunocompromised pt, used in life threatening situations respectively
bacteriostatic - slower, Yes, not advised, not advised
bacteriocidal - faster, no, yes, yes
why do bacteriostatic compounds require a functioning immune system
bacteriostatic compounds keep microbes constant so they can’t replicate so they need the immune system to step in and finish the job
what is more than 80% of the antibiotics we make used for?
to feed animals to treat food and not for actual tx of disease
what differentiates between therapeutic and preventive antimicrobials
the specificity of the target – therapeutic is more specific –> they target structures and physiological function
can some compounds be both bacteriostatic and bacteriocidal
yes they can – they can be bacteriostatic at some concentrations and then bacteriocidal at another concentration
what can happen with the addition of two compounds aimed at killing microbes
- they can be indifferent (no change)
- can be synergistic: work cooperatively together to kill microbes a lot quicker
- can be antagonistic: can antagonize each other hence getting worse results
what is selective toxicity
compounds with minimal or no effect on host cells but maximum effect against the infecting microorganism
what are some examples of ideal targets unique to infecting microorganisms
peptidoglycan (antibacterial) ergosterol (antifungal) reverse transcriptase (antivirals)
what are some alternative targets for infecting microorganisms
targets that are suitably different from that of the host cell equivalent
which microbial groups are harder to achieve with?
eukaryotes because we as humans are also eukaryotes so they are lots of similarities so must be really specific/unique with the target
why do some compounds only have an application in prevention and what is an example?
an example would be disinfectants – they only have a target in prevention because their general mechanism of action means they will be harmful to living tissue
what is the importance of penicillin generations
they are some chemical changes between each that help improve half life and other pharmacological aspects
what are natural sources of antibiotics
actinomycetes
filamentous fungi
bacteria especially streptomyces
where is penicillin originally from
penicillium chrysogenum though it is now produced semi synthetically
other sources of antibiotics
end products (secondary metabolites) of fermentation pathway
synthetic: quinolones (by product of antimalarial drugs)
analogs of nalidixic acid, quinolone, or derived ring (fluoroquinolone)
