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MICRB 265 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

OD is representative of ____

A

total cell count (# of intact cells) not the viable cell count

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2
Q

Microorganisms are not killed instantly, rather population death usually occurs _______

A

exponentially

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3
Q

A measures of agent’s killing efficiency of bacteria

A

-decimal reduction time- time to kill 90%

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4
Q

Killing efficiency of bacteria agent is affected by ____ cells. They are _____. We need to be sure that they are ____

A

-persister cells
-viable but nonculturable (VBNC) cells
-dead because once they recover they may regain the ability to reproduce and cause infection

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5
Q

Controls of bacterial populations are ____

A

reversible and irreversible

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6
Q

Types of controls of bacterial populations

A

-bacteriostatic
-bactericidal
-bacteriolytic

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7
Q

bacteriostatic (def.) + graph

A

-prevents growth but doesn’t kill bacteria
-viable cell count = total cell count but cell number is static until agent is removed
-reversible

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8
Q

bactericidal (def.) + graph

A

-kills cells but not lyse them
-total cell count (OD) stays stable but viable cell count reduces
-somewhat reversible

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9
Q

bacteriolytic (def.) + graph

A

-kills cells and lyse them when they die
-viable cell count = total cell count
-generally irreversible

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10
Q

cell number is ____ on normal graph; cell number is _____ on log graph

A

-exponential
-linear

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11
Q

5 methods of killing microbial cells

A

-sterilization
-disinfection
-sanitization
-antisepsis
-chemotherapy

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12
Q

sterilization (def.)

A

-destruction or removal of all viable organisms (no bacteria or endospores)

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13
Q

disinfection (def.)

A

-killing, inhibition or removal of pathogenic organisms but not endospores (ex. disinfectants), usually used on inanimate objects

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14
Q

sanitization (def.)

A

-reduction of microbial pop’n to levels deemed safe by public health standards (more bacteria survive than disinfection)

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15
Q

antisepsis (def.)

A

-prevention of infection of living tissue by micro-organisms
-chemical agents that kill or inhibit growth of microorganisms when applied to surface of tissue

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16
Q

chemotherapy aka ____ (def.)

A

-antibiotics
-kill or inhibit internal microorganisms

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17
Q

4 methods to control bacterial growth + main types of each method

A

-physical methods (heat + radiation)
-chemical methods (gas + liquids)
-mechanical methods (filtration)
-biological methods (antimicrobials)

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18
Q

high moist heat: type of bacterial growth control method? function? example?

A

-physical
-destroys viruses, fungi, bacteria, endospores
-autoclaving (used in lab, dentists); form of sterilization

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19
Q

low moist heat aka _____: type of bacterial growth control method? function? example?

A

-pasteurization
-physical
-controlled heating at temp below boiling (73 C)
-does not sterilize but kills most pathogens present and slow spoilage by reducing total load of organisms present
-used for milk, beer, other beverages

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20
Q

UV radiation: type of bacterial growth control method? function? example?

A

-physical
-260 nm is the most bactericidal; absorbed by DNA -> doesn’t kill endospores well & doesn’t lyse cells
-cause thymine/cytosine dimers which prevent replication and transcription
-only surface sterilization because it does not penetrate glass, films, water etc.
-used for water treatment (need to move water to surface)

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21
Q

Gamma radiation: type of bacterial growth control method? function? example?

A

-physical
-penetrates deep into objects & make DSB in DNA, ROS, membrane damage
-kills living organisms/ bacterial endospores but not viruses
-used for sterilization, pasteurization of antibiotics, hormones, sutures, plastic supplies, food

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22
Q

mechanical methods to kill microbes involve ____

A

movement of microbes with filters

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23
Q

mechanical methods to kill microbes with liquid samples

A

-membrane filtration pass through 0.2 um filter (bacteria can’t pass)

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24
Q

mechanical methods to kill microbes with gaseous samples (air)

A

-membrane filtration containing high efficiency particulate air (HEPA0 filter

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25
Chemical methods to kill microbes (6)
1. phenolics 2. alcohols 3. halogens 4. aldehydes 5. quaternary ammonium compounds 6. hydrogen peroxide
26
phenolics are commonly used as ______; they act by _______; they kill _____ but do not kill ______; effective in the presence of _____; ____-lasting; problem: _____; structure based on ______; example: _____
-lab and hospital disinfectants -denaturing proteins and disrupting cell membranes -bacteria, including mycobacterium tuberculosis, fungi and enveloped viruses -spores -organic material -long -bad odor & can cause skin irritation -phenol (benzene ring + OH) -triclosan
27
alcohols are the most widely used ______; effect on bacteria, fungi, endospores; kills _____; denatures _______; structure based on ____; example: ______
-disinfectants and antiseptics (used on skin) -bactericidal, fungicidal but not sporadical -enveloped viruses -proteins and possibly dissolve membrane lipids (conc. dependent) -alcohol (OH) -ethanol (50-70%), isopropanol
28
halogens are ____; oxidizes _____ and iodinates ______; kills _____; at high conc. may kill _____; problem: _____; structure based on _____; examples: _____
-skin antiseptic -cell constituents -proteins -bacteria, fungi, viruses -spores -skin damage, staining, and allergies can be a problem -halogens (F, Cl, I, Br) -halazone, triiodide
29
aldehydes do what; stop _____; kills _______; structure based on _______; examples: _______
-crosslink proteins; used to preserve tissue -metabolic activity -most bacteria and fungi including spores -aldehyde (O=CH) -formaldehyde, gluteraldehyde
30
Quaternary ammonium compounds are detergents that have ______; effective _______; kills ______; safe and easy to use; inactivated by ______; structure based on _____; examples: _____
-antimicrobial activity -disinfectants -most bacteria but not M. tuberculosis or endospores (mild); kills enveloped viruses and some fungi -hard water and soap -4o amine (ammonium : N+) -cetylpyridinium chloride, benzalkonium chloride
31
hydrogen peroxide (funfact: ROS) kills _____; oxidized ________; can put on ______; structure: ____
-most viruses, bacteria, and fungi -proteins, lipids, and sugars -skin + solid surfaces -H2O2
32
Chemotherapeutic agents (def.) + examples; where do they come from?
-chemical agents used to treat disease -antibacterials, antifungals, antivirals -nature (plants, bacteria, fungi-> they are ancient)
33
Alexander Fleming accidentally discovered _______ . He called the secreted material mould juice until finally deciding on _____.
-Penicillium (a fungi that commonly causes food spoilage) -penicillin
34
Selective toxicity (def.)
ability of drug to kill or inhibit pathogen while damaging host as little as possible
35
Therapeutic dose (def.)
drug level required for clinical treatment
36
Toxic dose (def.)
drug level at which drug becomes too toxic for patient (i.e., produces side effects)
37
Therapeutic index (def.)
ratio of toxic dose to therapeutic dose
38
Side effects (def.)
Undesirable effects of drug on host cells
39
Narrow spectrum drugs (def.)
Attack a few specific organisms
40
Broad spectrum drugs (def.)
Attack a wide range of organisms
41
Minimal inhibitory concentration (MIC) (def.)
lowest concentration of drug that inhibits growth of pathogen
42
Minimal lethal concentration (MLC) (def.)
lowest concentration of drug that kills pathogen
43
Two ways to determine effectiveness of antimicrobials
-dilution susceptibility tests for MIC -disk diffusion tests (Kirby Bauer)
44
Dilution susceptibility test (descr.)
-take inoculating media containing different conc of drug -broth/agar with lowest concentration showing no growth = MIC -for broth, tubes showing no growth can be subcultured into drugfree medium; broth from which no microbe can be recovered is MLC
45
Disk diffusion tests (Kirby Bauer) (descr.)
1. inoculate nutrient agar plate with liquid culture 2. place disk containing antimicrobial agent on surface 3. Incubate for 24-48 h 4. Measure zones of inhibition (ZOI) = no growth around disks
46
antibiotic targets
-inhibitors of cell wall synthesis -protein synthesis inhibitors (rna poly, ribosomes, mRNA) -metabolic antagonists -nucleic acid synthesis inhibition (DNA gyrase etc)
47
8 Things to consider about antibiotics
1. ability of drug to reach site of infection 2. susceptibility of pathogen to drug 3. ability of drug to reach conc in body > MIC of pathogen 4. amount given 5. route of administration (topical, oral intravenous) 6. speed of uptake 7. rate of clearance (elimination from body) 8. toxicity
48
There are many classes of _____ but only 1 news class has been discovered in the last ____
-antibiotics -60 years
49
Classes of antibiotics
50
Penicillins (B-lactam) ate ________ antibacterial effective against mainly _____; mode of action: _____. acts only on _____. structure allows it to _____. antibiotic resistance?
-narrow spectrum -gram-positive bacteria -blocks enzyme that catalyzes transpeptidation (cross links in peptidoglycan), prevents synthesis of complete cell walls leading to lysis of cell -growing bacteria that are synthesizing new peptidoglycan -bind to active site of enzyme because it looks like peptide bond -easy to develop resistance
51
penicillin G? penicillin V? ampicillin? carbenicllin? methicillin? ticarcillin?
-high activity against gram +, low against gram -; destroyed by acid and penicillinase -same spectrum; more acid-resistant than penicillin G -broader spectrum, active against gram +/-, acid stable (consume orally) -active against gram - (pseudomonas and proteus), acid stable, not well absorbed by small intestine -penicillinase-resistant but less activate than penicillin G; acid-labile (destroyed by acid) -similar to carbenicillin, but more active against pseudomona
52
Cephalosporins are structurally and functionally similar to _____; ____ antibiotics that can be used by most patients allergic to _____; 1st gen targeted ____ but later gen also target _____
-pencillins -broad spectrum -penicillin -gram + -gram -
53
Vancomycin + Teicoplanin are _____; inhibit _____; vancomycin is important for _____
-gram + glycopeptide antibiotic -cell wall synthesis (binds to N-acyl-D-Ala-D-Ala motif) -treatment of antibiotic-resistant MRSA and enterococcal infections
54
Aminoglycosides is a large group all with _____; example: ____; antibacterial with activity against _____; binds to _____, interfere with ______
-cyclohexane ring, amino sugars -streptomycin -gram - aerobic and facultative anaerobic bacteria -30S ribosomal subunit -protein synthesis by directly inhibiting the process and by causing misreading of mRNA
55
tetracyclines all have ____; are ____spectrum, _____; combine with _____; inhibits binding of _____; sometimes used to treat ____
-four-ring structure to which a variety of side chains are attached -broad -bacteriostatic -30S ribosomal subunit -aminoacyl-tRNA molecules to the A site of ribosome -acne
56
macrolides contain ______; eg _______, ______ spectrum, usually ______; binds to ______, inhibits ______, used for patients allergic to ______
-12- to 22-C lactone rings to one or more sugars -erythromycin -broad -bacteriostatic -23S rRNA of 50S ribosomal subunit -peptide chain elongation -penicillin
57
sulfa drugs are _____; ____; have ____. ex. _____, sulfa drugs are selectively toxic due to ______
-metabolic drugs -bacteriostatic -sulfur -sulfanilamide, furosemide -competitive inhibition of folic acid synthesis enzymes
58
Folic acid is _____, necessary for _____, cofactor in ______; structurally related to _____. PABA is used for the synthesis of ______ and is made by many pathogens
-Vitamin B9 -DNA synthesis -many biological rxns -sulfanilamide, a PABA (p-aminobenzoic acid) analog -folic acid
59
Trimethoprim is a synthetic antibiotic that also interferes with ______; _____ spectrum. Can be combined with ______. Combination blocks _______, has a variety of side effects including ______, Used to treat ____; binds to different enzyme than _____
-folic acid production -Broad -sulfa drugs to increase efficacy of treatment -two steps in folic acid pathway (harder to develop resistance) -abdominal pain and photosensitivity reactions -UTIs -sulfa drugs
60
Quinolones are ____-spectrum synthetic drugs containing the ______, act by inhibiting _____, ______, Excellent ______, ex. _____
-Broad -4-quinolone ring - bacterial DNA gyrase and topoisomerase II (needed for replication) -Bactericidal -tissue penetration -ciprofloxacin
61
Lipopeptides: Only effective against _____ organisms but very effective. Used against ______. Inserts into membrane near ______ ex.______
-Gram positive -S. aureus but can be toxic -phosphatidylglycerol, then aggregates, changing membrane curvature and allowing little holes to form (depolarizes membrane) -daptomycin
62
mechanisms of antimicrobial resistance (7)
-efflux pumps -decreased uptake -target alternations -alternative enzyme -inactivating enzyme -sporulation -shutting down cell growth
63
antimicrobial resistance comes from ____ (3)
-microbial warfare -horizontal gene transfer (ex. plasmid) -evolutionary pressure from widespread antibiotic use
64
antimicrobial resistance can exist in a pop'n because ____
eventhough on average there is one mutation per cell, in a typical infection, you can have billions or trillions of cells meaning more opportunity to have advantageous mutations
65
antimicrobial resistance is a huge problem because _____
-once resistance is developed, it can be transmitted -a specific resistance mechanism can give resistance to many classes of drugs -microbes in abscesses or biofilms growing slowly and may not be susceptible -resistance mutants arise spontaneously and are then selected for

MICRB 265 (12 decks)

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