Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PHA112 > Microbiology 9 > Flashcards

Microbiology 9 Flashcards

1
Q

when were antibiotics first introduced?

A

1940s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the 7 main groups of antibiotics?

A
  • penicillins
  • cephalosporins (ceftriaxone)
  • macrolides (erythromycin)
  • fluoroquinolone (ciprofloxacin)
  • sulfonamides (sulfasalazine)
  • tetracyclines (tetracyclin)
  • aminoglycosides (tobramycin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what must an antibiotic be?

A

more toxic to microorganism than host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what do all beta-lactams have?

A

beta-lactam ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are sulphonamides?

A

synthetic chemicals (first antimicrobial drugs - 1930s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what do sulphonamides do?

A

competitively inhibits dihydropteroate synthetase (DHPS) - enzyme involved in folate synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where do humans obtain folate from?

A

food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what do sulphonamides have a similar structure to?

A

para-aminobenzoic acid (PABA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do bacteriostatic agents do?

A

halt growth (bacteria recover when drug stopped)

  • limit spread of infection
  • growth restarts
  • tetracycline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what do bactericidal agents do?

A

kills bacteria for period of time

  • useful in critically ill patients
  • e.g. meningitis, endocarditis, septicaemia
  • critical cell death events already initiated
  • beta-lactams
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe what is happening in this graph?

A
  • time dependent rate of kill rises to maximum and remains constant
  • conc dependent drug increases rate of kill as [drug] increases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

in concentration dependent drugs what does the rate of kill eventually become?

A

constant

(limited by agent diffusion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

bacteriostatic outcomes

A
  • macrolides
  • linezolid
  • clindamycin
  • tetracyclin
  • chloramphenicol
  • trimethoprim-sulfamethoxazole
  • isoniazid (bacteriostatic against lag-phase and dormant TB)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

bactericidal outcomes

A
  • fluoroquinolones
  • beta-lactams
  • glycopeptides (e.g. vancomycin)
  • aminoglycosides
  • daptomycin
  • metronidazole
  • nitrofurantoin
  • isoniazid (bacterial against lag phase mycobacteria)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does the general outcome depend on?

A
  • pathogen
  • bacterial load
  • [drug]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the meaning of broad spectrum?

A

effective against a wide range of bacterial species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the meaning of narrow spectrum?

A

effective against a limited number of different bacterial species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what do penicillins target?

A
  • gram negative bacteria
  • gram positive bacteria
  • chlamydiae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what do sulphonamides, cephalosporins, quinolones and carbapenems target?

A
  • gram negative bacteria
  • gram positive bacteria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what do streptomycins target?

A
  • mycobacteria
  • gram-negative bacteria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what do tetracyclines target?

A
  • gram negative bacteria
  • gram positive bacteria
  • chlamydiae
  • rickettsiae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what do isoniazids target?

A

mycobacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what do polymyxins target?

A

gram negative bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what do vancomycins target?

A

gram positive bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what needs to be considered when choosing antibiotics?
- selectivity (will it treat what you want) - toxicity (will it poison) - therapeutic index (toxic dose/effective dose)
26
what does TARGET stand for?
T - treat A - antibiotics R - responsibly G - guidance E - education T - tools
27
disinfection?
removes microbes from inanimate surfaces
28
what is disinfection not the same as?
sterilisation
29
what does disinfection do?
- removes infection risk - prevents spoilage of perishable goods
30
what are disinfectants?
chemicals with ability to destroy/inhibit microorganisms
31
what are disinfectants not the same as?
antibiotics
32
give examples of disinfectants?
- alcohols (ethanol) - aldehydes (formaldehyde) - biguanides (chlorhexidine) - halogens (hypochlorites) - metals (silver) - hydrogen peroxide - phenols (chlorocresol) - surfactants (cationic QACs)
33
what is antisepsis?
removal of microbes from living surfaces (should = non-toxic)
34
what is antisepsis used for?
used to reduce microbial populations (skin before surgery) (controlling microbial contamination of staff hands)
35
disinfection and antisepsis are NOT the same thing however what are they both?
broad spectrum
36
what can the active ingredient be in both antisepsis and disinfection?
can be the same [active] lower in antiseptics
37
what is a preservative?
a substance added to a product (medicinal, food etc) designed to prevent degradation by microbes/unwanted chemical changes
38
what can preservatives also do?
preserve products by drying, refrigeration, UV-C irradiation
39
give examples of how preservatives have been used in prehistoric times to prevent food spoilage?
- salt used to preserve meat - vegetables preserved in vinegar
40
give examples of how preservatives are used in pharmaceutics?
- increase shelf life by preventing microbial growth and degradation - must = non-toxic to humans e. g. lactic acid, sodium benzoate, syrup
41
define osmosis?
net movement of solvent from high to low conc through membrane
42
what is an isosmotic solution (isotonic)?
no net movement of water
43
what is hypoosmotic solution (hyptonic)?
- water moves into cell - may cause cell to burst if wall = weak/damaged (LYSIS)
44
what is a hyperosmotic solution (hypertonic)?
- water moves out of cell - cytoplasm shrinks (PLASMOLYSIS)
45
how does resistance to spoilage increase?
high concentrations of sugars / PEGs
46
what is water activity (Aw)?
proportion of uncomplexed water available to support microbial growth
47
as Aw decreases...
growth rate decreases until **minimal growth-inhibitory** Aw reached
48
what are the approximate Aw values?
- bacteria: 0.90-0.95 - yeasts and moulds: 0.80-0.88 - no microbial growth expected less than/equal to 0.6
49
what can a lower value of Aw of aqeuous formulations do?
increase resistance to microbial attack - high conc of sugars/polyethylene glycols
50
what can Aw be reduced by and how?
- desiccation - removal of water vapour of products - through silica gel/ molecular sieve during manufacturing - can = included in blister packs, packagin etc as separate items
51
what can the accumulation of condensation on surface of low Aw products permit?
surface yeast and mould spoilage
52
what do paper discs contain?
known [antibiotic] which diffuses into inoculated sugar
53
[antibiotic] decreases with log distance until..
MIC reached - produced clear inhibitory zone after incubation which can be measured to determine sensitivity
54
multiple antibiotics are tested in what?
parallel
55
e-test strip diffusion assays
- same principle as disc diffusion - [antibiotic] changes along length of strip
56
what can e-test strip diffusion assays be used to test for?
antibiotic synergy - stack on top of each other - layer at side
57
what quantitative result do e-test strip diffusion assays provide?
MIC value
58
what is the minimum inhibitory concentration?
lowest concentration of chemical which prevents visible growth of a bacterium
59
what is the minimum bactericidal concentration?
lowest concentration of an antibacterial agent required to kill particular bacterium
60
where can resistance genes come from?
- bacteria which survived treatment - antibiotic producers - bacteria that exist alongside antibiotic producers
61
how does antibiotic resistancy happen?
1. lots of germs. few drug resistant 2. antibiotics kill bacteria causing illness + good bacteria protecting body 3. drug-resistant bacteria not allowed to grow and take over 4. some bacteria give drug-resistance to other bacteria, causing problems
62
what is innate resistance?
inherent ability of bacteria to resist particular antibiotic - lack of cell wall (mycoplasms Vs beta lactams) - abnormal antibiotic targets
63
what is acquired resistance?
result of changes to normal genome of bacteria
64
what is transformation?
direct uptake of DNA through cell membrane
65
what is transduction?
intro of genetic material via viral vector
66
what is conjugation?
transfer of genetic material between 2 directly connected bacteria
67
how can antibiotic resistance spread?
- drug-resistant bacteria can remain on meat - unclean hands - drug-resistant bacteria in animal faeces remain on crops - fertilizer/water containing animal faeces used on crops
68
ANTIBIOTIC RESISTANCE MECHANISMS exclusion
- decrease uptake (cell wall modification) - increase export (efflux pump production)
69
ANTIBIOTIC RESISTANCE MECHANISMS inactivation
- modify antibiotic (aminoglycoside acetylation) - destroy antibiotic (B lactamase production)
70
ANTIBIOTIC RESISTANCE MECHANISMS target modification
- target protection - enzymatic modification - change/bypass of target site
71
what resistance mechanism can work for both antibiotics and disinfectants?
efflux pumps
72
what are the disadvantages to developing new antibacterials?
- high development cost (\>2.5 billion dollars to get 1 prescription-only med to market) - high failure rate (approx 20% success rate in phase I) - low return ( acute use only 5-7 days dosing) - high risk of resistance
73
FDA and EMA are incentives to what?
increase pharma interest
74
most antibacterials in CT are new derivatives of existing classes (e.g. cephalosporins, tetracyclines/aminocyclines, FQs) give the advantages of these?
- increased activity - fewer side effects - lower resistance
75
what are the alternatives to traditional antimicrobial agents?
- natural products - bacteriophages and derived proteins
76
natural products
- tea + honey have antibacterial compounds - black \< green \< white tea - 4 main catechins (polyphenols) in green tea - e.g. epigallocatechin gallate, epicatechin, epicatechin 3- gallate, epigallocatechin - honey = high sugar content, polyphenols, lysozymes, hydrogen peroxide POTENTIALLY PRODUCE BROAD SPECTRUM
77
bacteriphages and their derived proteins?
- take advantage of normal phage lytic replication - can = highly specific - different pharmacology compared to conventional antimicrobials

PHA112 (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions