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OCTC-Micro-Chapter 10
OCTC-McElroy's class Summer 2013
61
Microbiology
Undergraduate 1
06/08/2013

Additional Microbiology Flashcards

 


 

Cards

Term
Antiviral drugs work by being...
Definition
analogs of components of viral DNA or RNA
Term
Acyclovir and AZT (azidothymidine) are nucleotide analogs in treatment of
Definition
HIV
Acyclovir treats Herpes virus
Term
When nucleotide analogs become incorporated into the pathogen’s DNA:
Definition
Distorts the shape of pathogen’s DNA and RNA
Which prevents replication, transcription, or translation
Term
Nucleotide analogs make potent antiviral and anticancer drugs because…
Definition
Viruses and cancer cells typically replicate faster than normal cells.
Term
Viruses are _______ more likely to incorporate an analog into the viral DNA or viral RNA than host the cell.
Definition
100X
Term
Spectrum of action
Definition
The number of different kinds of pathogens a drug acts against
Term
Diffusion susceptibility test AKA...
Definition
Kirby-Bauer test
Term
Diffusion susceptibility test procedure
Definition
1. Uniformly inoculate Petri plate w/pathogen
2. Small disks of drugs are firmly arranged on the plate
3. Plate is incubated for _____ hours and examined
4. Plates are examined for zones of inhibition
5. Larger the zone of inhibition = more effective drug
Term
Researchers classify drugs as:
Definition
Susceptible, Intermediate, Resistant to each drug
Term
Diffusion Susceptibility Test tells us:
Definition
1. Which drug is the drug of choice.
2. Which drug is the microbe most susceptible to.
Term
MIC test:
Definition
lowest dosage of that the drug of choice will most be effective
Term
MIC test procedure:
Definition
Series of dilutions of the drug of choice is place in nutrient broth
Standard amount of bacteria is added to each broth tube.
After incubation, clear broth indicates that bacteria were either inhibited or killed
Term
MIC is:
Definition
bacteriostatic
Term
MBC test:
Definition
determines the dosage of the drug to be an effective bacteriocidal.
Term
MBC Samples are taken from and transferred to:
Definition
clear MIC tubes or zones of inhibition of Diffusion Susceptibility Test = Kirby Bauer, to plates containing a drug-free growth medium
Term
Any growth of bacterial colonies on a MBC plate indicates that concentration of antimicrobial drug is…
Definition
Only bacteriostatic not bactericidal
Term
List routes of drug administration:
Definition
Topical or Local
Orally
Intramuscularly (IM)
Intravenously (IV)
Term
Topical or local =
Definition
Application of drug if infection is external
Term
Oral – simplest
Definition
Lower drug concentrations
No reliance on health care provider
Patients do not always follow prescribing information
Patients may quit taking the drug
Term
Intramuscular
Definition
Requires needle for administration
Some patients refuse shots
Reaches a higher drug concentration faster than oral administration
Drug concentration diminishes as liver and kidneys remove drug from circulation
Concentration never as high as IV administration
Term
Intravenous
Definition
Requires needle or catheter
Drug in blood is initially very high drug concentration
Remains high, constant delivery
Term
What are three main categories of side effects?
Definition
Toxicity
Allergies
Disruption of normal microbiota
Term
Toxicity:
Definition
Ideally antimicrobials drugs are toxic to pathogens and harmless to humans; however many drugs have toxic side effects
Exact cause of many adverse reactions poorly understood
Many Drugs may be toxic to kidneys, liver, or nerves
Term
Flagyl
Definition
Antiprotozoan drug
Term
Flagyl may cause a harmless temporary condition called
Definition
“black hairy tongue”
Term
Tetracycline causes
Definition
discoloration of teeth
Term
Toxicity in pregnant women causes:
Definition
side effects to the fetus (accutane)
Term
Allergies: Some drugs trigger allergic:
Definition
immune responses
Term
Although allergic reactions are rare, they may be:
Definition
life threatening and may cause Anaphylactic shock
Term
.1% of Americans have anaphylactic reactions to:
Definition
Penicillin
Term
Disruption of Normal Microbiota/Flora
Definition
May allow opportunistic pathogens to increase and result in secondary infections
Term
Long term use of broad spectrum antimicrobials often result in:
Definition
explosion of overgrowth of normal flora: Candida albicans
Term
Candida albicans of the vagina and mouth:
Definition
causes vaginitis yeast infection and thrush after long term
Term
Superinfections or multiplication example:
Definition
Clostridium difficile
Term
Clostridium difficile normally resides ______ is held in check by _________.
Definition
in the colon; normal microbiotica/normal flora
Term
If normal flora is destroyed by long term treatment of antibiotics; C. difficle can multiply and causes a potentially fatal condition called:
Definition
Pseudomembranous colitis
Term
Secondary infections like C. difficile are of greatest concern for hospitalized patients that are already:
Definition
immumocompromised and exposed to resistant pathogens
Term
Not all microbes of the _________ are equally sensitive to a given drug
Definition
same population
Term
mutant strains are:
Definition
naturally partially or completely resistant to a given drug
Term
In the absence of antimicrobial agents, the resistant (mutant) cells are:
Definition
in the minority and usually less efficient than normal cells
Term
When antimicrobial agent is present, sensitive cells are _______ while the resistant cells
Definition
inhibited or die continue to grow
Term
Resistant cells then replace:
Definition
sensitive cells as the majority in the population
Term
Antimicrobials do not produce:
Definition
resistance!
Term
Bacteria can acquire resistance in 2 ways:
Definition
1. New mutations of chromosomal genes
2. Acquisition of R-plasmids via transformation, transduction, and conjugation
Term
What are 5 ways bacteria develop resistance?
Definition
1. Can mutate their DNA to produce enzymes
2. Can mutate their DNA to alter the shape of proteins called porins
3. Can alter receptors that so that drug can no longer attach to it or drug binds less effectively to microbe
4. Can alter their metabolic pathways that the drug targets
5. Pump the drug out of the cell before the drug can act
Term
Resistant Microbes mutate their DNA to produce enzymes such as beta-lactamase (Penicillinases enzyme) that destroys (it opens the B-latam ring) or deactivates the beta-lactam of drug- ex:
Definition
Penicillinases enzyme renders penicillin inactive (MRSA)
Term
Resistant Microbes mutate their DNA to alter the shape of proteins called porins in microbe’s cell membrane- ex:
Definition
These mutated porin slows or prevents entry of drug into the cell.
Mutated porins give bacteria resistant to penicillin and tetraclycine
Term
Resistant Microbes alter receptors that so that drug can no longer attach to it or drug binds less effectively to microbe - ex:
Definition
(HIV and Trypanosoma brucei alter their receptors through mutation)
Term
Resistant Microbes alter their metabolic pathways that the drug targets- ex:
Definition
Example: Resistance against Sulfa Drugs
1. Produce more PABA
2. Resistant microbes abandon synthesis of folic acid and absorb it from the environment
Term
Antimicrobials facilitate replication of resistant cell that were:
Definition
already in population
Term
What is Multiple Resistance?
Definition
Pathogen can fight off to more than one drug at a time Especially when different R-plasmids are exchanged
Term
Multi-resistant strains of bacteria develop in:
Definition
Hospitals and nursing homes, where the constant use of many kinds drugs eliminates sensitive cells and allows the growth of resistant strains
Term
What is Cross Resistance?
Definition
When one antimicrobial agent
can fight more than one drugs
Especially when drugs have similar structures
Term
Examples of Cross Resistance
Definition
Streptomycin, Neomycin, Gentamicin, Kanamycin
Term
Multiple Resistance and Cross Resistance create:
Definition
superbugs.
Term
Superbugs:
Definition
pathogens that are resistant to many drugs
Term
Ex. Of Superbug strains:
Definition
Staphylococcus, Streptococcus, Enterococcus, Pseudomonas, Plasmodium
Term
Four ways to Retard the Develop of Resistance:
Definition
High concentrations of drug maintained in patient for long enough time to kill all the pathogen’s sensitive cells and inhibit resistant cells long enough for immune system to destroy them.
Use a combination of antimicrobial agents so that pathogens resistant to one drug will be killed by another drug
Limit use of antimicrobials to necessary cases
Develop new variations of existing drugs to resistant strains
Second-generation drugs then Third-generation
Term
Synergistic drugs:
Definition
one drug enhances the effect of a second drug Example: Penicillin and streptomycin
Term
Penicillin inhibits the formation of the:
Definition
cell wall and makes it easier for streptomycin to get inside the pathogen and interfere with protein synthesis
Term
Antagonistic drugs:
Definition
drugs that interfere with each other
Example:
Drugs that slow bacterial growth are antagonistic to drugs that act only against growing and dividing cells
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