Week7C1 : Control of microorganisms Flashcards
What is sterilization?
The killing or removal of all viable organisms (including
endospores).
What is inhibition?
Effectively limiting microbial growth.
What is decontamination?
The treatment of an object to make it safe to handle.
What is desinfection?
Directly targets the removal of all pathogens, not necessarily all microorganisms
What is the most widely used method for controlling microbial growth?
heat treatment.
What are the three physical methods?
heat
filtration
radiation
What are the three antimicrobials used internally
antibiotics
antifungal
antivirals
T or F : The time necessary to kill a defined fraction is independent of the initial cell concentration.
true
T or F : The D is not dependant on the population size while the TDT is
true
Sterilization is acheived by ___ minutes at ___˚C
10-15 minutes
121˚C
T or F : pasteurization kills listeria monocytogenes
false, it reduces the microbial load.
Flash pasteurization is ____ ˚C for ___ seconds
72 ˚C
15 seconds
bulk pasteurization is ____ ˚C for ___ minutes
65˚C
30 minutes
How does heat kills
denature proteins
How does radiation kills
breaks DNA so inhibit replication
What microorganism can resist an elevated level of radiation
deinoccoccus radiodurans
What are the two types of filters
- depth filters
2. memrbane filters
What are the three clases of antimicrobial agents?
- bacteriostatic
- bacteriolytic
- bacteriocidal
What is the only type of microbial agent that reduces the total number of cells and the total number of viable cells
bacteriolytic
When the total cell count and the viable cell count are not decreased, the antimicrobial agent is ___
bacteriostatic
When the total cell count is not decreased but the total viable count is decreased, the antimicrobial agent is ___
bacteriocidal
What is the MIC?
minimum inhibitory concentration : the smallest amount of an agent that will inhibits the growth
What is the MLC?
minimum lethal concentration (MLC) : lowest concentration of an agent that kills a test organism
What is the MBC?
minimum bacteriocidal concentration. It is the lowest concentration of agent that kills a test bacterium.
On a disc diffusion assay, the line delimiting the zone of microbial growth and the zone of no microbial growth is the ____
MIC
Name the four types of chemical antimicrobial agents for external use
- sterilants
- disinfectants/sanitizers
- antiseptics
- antimicrobial drugs
What is the only type of external antimicrobial agent that kills endospores
sterilants
What are the different antimicrobial drug classes
- antibiotics
- antifungal
- antiviral
Disinfectants/Sanitizers are applied to ___
applied to nonliving objects or surface (can be toxic for
animals/humans).
Antiseptics are applied to_____
surface of living tissues or skin (must not be toxic for
animals/humans).
**Sodium hypochlorite is a ___
sterilant, desinfectant and antiseptic
Antimicrobial drugs can either be ___ or ___
bacteriostatic
bacteriocidal
Only ___ and _____ (sterilants) can kill endospores
halogens and alkylating agents
What are the various targets of antimicrobial drugs?
- cell wall synthesis
- folic acid metabolism
- cytoplasmimc membrane structure and function
- lipid biosynthesis
- Protein synthesis
- Protein synthesis (30s inhibitor)
- Protein synthesis (50s inhibitors)
- DNA directed RNA polymerase
- RNA elongation
What was the name of the first antimicrobial drug?
salvarsan
What are growth factors analogs?
structure similar to growth factors but can’t functinon in a cell
What are the two types of growth factors analogs seen in class
sulfa drugs
isoniazid
***Sulfanilamide is an example of a ____ and it is an analgoue of ____
growth factor analog (sulfa drug)
p-aminobenzoic acid
Isoniazid is a growth factor effective against ____ that interferes with the synthesis of ____
mycobacterium
mycolic acid
What are the three types of synthetic antimicrobial drugs seen in class
- growth factors analogs
- nucleic acid analogs
- quinolone
Quinolones are antibacterial
compounds that interfere with ___
DNA gyrase (control DNA supercoiling).
___ are one of the most important groups of antibiotics of all time discovered by alexander fleming
B-Lactams
B-Lactams group includes :
penicillins, cephalosporins, and cephamycins.
Penicillins are effective against gram ____ and they inhibits the ____
positive
cell wall synthesis
What are the only two semisynthetic penicillin resistant to the enzyme b-lactamase
methicillin and oxacillin
T or F : penicillin are named after the mold they are isolated from
true
How does cephalosporins work
by inhibition of the cell wall synthesis
How does the b-lactam inhibitis the cell wall growth
binds the TPase (important enzyme for the cross-linking of the peptidoglycan wall)
the majority of antibiotics
we use came from the
bacteria ____
(80%)
streptomyces
**Streptomycin is an _____
aminoglycoside
***Streptomycin target the ______ and is bacterio___
target the 30s subunits and causes misreading of the mRNA
bacteriocidal
What are the 4 antibiotics isolated from proxaryotes groups seen in class
- aminoglycosides
- chloramphenicol
- macrolides
- tetracyclines
What is the target of chlorampehnicol?
binds the 23s rRNA and block peptide elongation
Chlorampehnicol is bacterio___
static
What is the target of macrolides
target the 50s subunit of the ribosome
What is the target of tetracyclines?
inhibits the 30s ribosomal subunit
Why are antiviral drugs more toxic than antibiotics
Most antiviral drugs also target host structures, resulting in toxicity
Most successful and commonly used antivirals are the _____
nucleoside analogs
***Fluconazole and nyastin inhibits ____
ergosterol synthesis
