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BDS2 BAMS > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

5 types of historic antibiotics

A

Plants

Beer

Salts

  • Preserve food
  • Hallophiles like salt - most are sensitive to salt

Chemicals

  • exclusion of certain selective targets for some MO
  • Dyes can penetrate into bacteria

Moulds
- Penicillin

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2
Q

what is the concept of repurposing

A

designed for something else but use them for something completely different

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3
Q

describe the penicillin discovery

A

Antibiotics

Zone of inhibition between bacteria and plate
- Fleming had insight to write down this - pass on information to people knowledgeable enough to purify it to be used

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4
Q

use of antibiotics in WWII

A

Antibiotics crucial

Die from open wounds from battle field get into wounds
- Gangrene

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5
Q

2 types of microbial growth control

A

physical

chemical

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6
Q

2 types of physical microbial growth

A
  • heat sterilisation

- radiation sterilisation

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7
Q

3 types of chemical microbial growth control

A

antiseptics (biological) and disinfectants (inanimate/surfaces)

natural antimicrobials

synthetic antimicrobials
- antivirals or antifungals

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8
Q

what is the ideal clinical scenario

A

the ideal way and our goal in patient care is the sterilisation of all contaminated equipment and surfaces

this is not practical

  • as you enter – no longer sterile
  • need to be cleaned and disinfected or covered with disposable barriers

PPE – protect yourself and the pt

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9
Q

8 examples of transmitted pathogens

A

Human Immunodeficiency Virus (HIV)

Herpes Simplex Virus types 1 and 2

Hepatitis B Virus (HBV)

Streptococci

Staphylococci

Mycobacterium tuberculosis

Cytomegalovirus

Some upper respiratory tract viruses

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10
Q

why is there a need for high level disinfectants over lower level ones and antiseptics

A

Disinfectants and antiseptics may be contaminated by resistant spores, Pseudomonas aeruginosa & Serretia marcesnes and may transmit infection.

Can be used partially – need high level disinfectants or antibiotics to prevent infection

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11
Q

4 basic methods of infection control

A

Disinfection of non-sterilizable surfaces and equipment

  • Cannot put into autoclave
  • Clean down chairs and handpieces
  • Multi surfaces (plastics, metals, polymers) only some autoclavable
  • Not all - need alternative methods

Heat sterilization of all compatible equipment

Handwashing techniques + appropriate antiseptics

Combined with appropriate barrier techniques:
- Masks, gloves and eye protection (PPE)

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12
Q

disinfectants

A

are strong chemical agents that inhibit or kill microorganisms
ideally kill

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13
Q

antiseptics

A

are disinfecting agents with sufficiently low toxicity for host cells→can be used directly on skin, mucous membranes, or wounds

similar to disinfectants but weaker
- low toxicity as need to be used in human body

some are quite potent

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14
Q

sterilants

A

kill both vegetative cells and spores when applied to materials for appropriate times and temperatures

disinfectants with added value can kill of spores

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15
Q

where are disinfectants used

A

Disinfecting agents with sufficiently low toxicity for host cells

Used directly on skin, mucous membranes or wounds (open sores, oral surgery)
- Don’t want to simulatenously harm pt when kill bacteria, fungi and viruses

E.g. chloroheidine

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16
Q

antisepsis is

A

use of chemicals to destroy most pathogenic organisms on animate surfaces (pre-surgical)

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17
Q

what are the properties of an ideal antiseptic

A

ideal antiseptic has to have similar properties as an ideal disinfectant

Primary importance is selective toxicity (unlike disinfectant)

  • Toxicity to microorganisms but not to human cells
  • Degree of selectivity depending on contacted tissues
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18
Q

5 examples of antiseptic use

A

Treatment of skin infections

Prevention of infections in cuts and wounds
- Any trauma – deliberate or accidental

Cleaning the skin area of surgery from microorganisms – pre-surgical

Prophylaxis and treatment of infections in mucosal areas such as mouth, nose and vagina that are open to environment

As a scrub for surgeons and the medical personnel

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19
Q

3 classifications of antiseptics

A

Those that denature proteins (cidal)
- Protein matter in most living organic orgnsims

Those that cause osmotic disruption of the cell (cidal)
- Pop; Burst balloon; Cannot reinflate

Those that interfere with specific metabolic processes (growth arrest/static

  • Slows them down; Static
  • Organisms can come back/grow again
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20
Q

what is the mechanism of action for phenols, iodine, alcohols, aldehydes and metallic compounds

A

dentaure proteins and DNA bases

  • hand wash
  • destroy protein/nucleic acid therefore destroy organism
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21
Q

what is the mechanism of action for cationic detergents

A

interfere with plasma membrane’s permeability and cause leakage of enzyme, coenzyme and metabolites

  • osmotic shock
  • slow it down to death

e.g. chlorohexidine

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22
Q

what is the mechanism of action for for oxidising compounds

A

oxidize functional molecules in the microorganisms

- Interfere with proteins – slow down – then kill

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23
Q

what are iodophores

A

Iodine and other free halogens oxidize the –SH groups of proteins and enzymes

  • produce -S-S- bonds and disrupts the structure and function of these
  • iodine containing molecules bind to sulphur groups on protein (many), disrupt the protein structure

Used either as an antiseptic or disinfectant

  • Low concentrations are antiseptic
  • High concentrations are disinfectant

one of the best
- surgical scrubs, ICU

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24
Q

what can iodophores kill

A

vegetative bacteria, mycobacteria, fungi, lipid containing viruses (spores on prolonged use)

one of the best
- surgical scrubs, ICU

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25
Q

what type of alcohols are effective antiseptics and disinfectant agents

A 
Ethyl alcohol (70% [60-90]) and isopropyl alcohol 
- drying out of ethyl alcohol kills bacteria – destabilises the membrane
26
Q

what is the decrease caused by ethyl alcohol on the skin in bacteria

A

90%

  • cleaning surfaces
  • preventative measure
27
Q

what is the mechanism of action for ethyl alcohol and what can it kill

A

Denature proteins and disturb the membrane permeability of bacteria
- Limited antibacterial spectrum

Rapidly kill vegetative bacteria, fungi and inactivate lipophilic viruses

28
Q

what is chlorohexidine used as

A

Water soluble chlorhexidine digluconate is used as an antiseptic

29
Q

mechanism of action for chlorohexidine

A

Most effective against Gram- positive cocci and less active against Gram-positive and gram-negative rods

  • Spore germination is also inhibited
  • broad spectrum

Strongly adsorbs to bacterial membranes and causes leakage of small molecules and precipitation of cytoplasmic proteins
- Longevity – high protein bound

Can be toxic if too much lead to anaphylaxis

  • Not broken down easily
  • Stains teeth
  • It is resistant to inhibition by blood or organic material
30
Q

name common oxidising agent

A

Hydrogen peroxide (H2O2) is commonest oxidizing compounds that have been used as antiseptics

31
Q

uses of oxidizing agents with concentration change

A

Concentrations potentially useful for antisepsis are effective against vegetative bacteria, higher concentrations are sporicidal

  • Useful – not 100% kill, standard skin antiseptic
  • Change concentration get disinfectant and sporicidal
  • 10-25%

Disinfection of respirators, acrylic resin implants, plastic eating utensils, soft contact lenses, cartons for milk or juice

32
Q

health warning of antiseptic, disinfectant and sterilant users (e.g. sodium hydrochloride, chlorohexidine)

A

short-term and long-term toxicity

general biocidal activity

accumulate in the environment OR in the patient’s/caregiver’s body – problematic

33
Q

2 examples of bacteria antibiotics used against

A

streptomyces

bacillus

34
Q

2 examples of moulds bacteria used against

A

penicillium

cephalosporium

35
Q

what are antibiotics

A

Naturally occurring antimicrobials
- An antibiotic is a chemical substance produced by one organism that is destructive to another.

Metabolic products of bacteria and fungi

Reduce competition for nutrients and space
- Maximise what nutrients are made to modify

36
Q

2 possible mechanisms of action for antibiotics

A

bacteriostatic

bacteriocidal

37
Q

4 cellular targets of antibiotics

A

cell wall

cell membrane

nucleic acid

protein synthesis

38
Q

8 characteristics of an ideal antimicrobial agent

A

selective toxicity against microbial target

minimal toxicity to the host

cidal activity (kills micro-organism)

long plasma half-life
- stick around in body for longer time

good tissue distribution
- ability to penetrate all of body – not compartmentalised

low binding to plasma proteins

oral and parental preparations
- IV – need to be day patient or in hospital for time period so not ideal

No adverse interaction with other drug

Difficult to get antibiotics that fits all

39
Q

4 main antimicrobial targets

A

Inhibition of cell wall synthesis
- Osmotically unstable

Inhibition of protein synthesis

Inhibition of nucleic acid replication and transcription
- Unwinding DNA

Injury to plasma membrane polymyxin B

Inhibition of synthesis of essential metabolites

40
Q

structural feature of peptidoglycan targeted by penecillin

A

Cross linked
- penicillin prevents cross link become unstable

Critical in terms of where antibiotics work
- Cause cell lysis

41
Q

2 types of inhibitors of cell wall synthesis

A

beta- lactams

glycopeptides

42
Q

beta-lactam inhibition of cell wall synthesis

A

Bind to ‘penicillin binding proteins’

Inhibition of cross-linking of cell wall

Accumulation of precursor cell wall units

Cell lysis

43
Q

glycopeptides inhibition of cell wall synthesis

A

Examples: vancomycin, teicoplanin

Bind to terminal D-ala-D-ala residues

Prevent incorporation of sub-unit into growing peptidoglycan

44
Q

how are different penicillin structures made

A

Different penicillin structures, Taken basic penicillin natural building block

Chemists have made semi synthetic versions by modifying branches to make different structures

45
Q

how to antibiotics cause inhibition of protein synthesis

A

Antibiotics work on different subunits of ribosome leads to loss of function of protein

Specific Sites of Protein Inhibition
- Penicillin inhibit cell wall
- Protein inhibitors act on ribosomes
inhibit different aspects of translation

46
Q

how do antibiotics cause nucleic acid inhibition

A

Super coiled DNA
- DNA gyrase unwinds specific section

Ciproflaxcin - stops this

47
Q

3 basic points antibiotics attack on bacteria and fungi replication

A

cell wall

protein

nucleic acid

48
Q

what drives the increase of Antimicrobial Resistance

A

Over use
- Ineffective empiric therapy
- Increase morbidity leads to More antibiotics prescribed
- Increased hospitalisation so even More antibiotics
- Increase health care resource use
Limited treatment alternatives thus more antibiotics and then mortality

49
Q

what creates antibiotic resistance

A

missuse of antibiotics selects for resistance mutants

50
Q

5 examples of antibiotic missuse

A

Using outdated or weakened antibiotics (no longer effective)

Using antibiotics for the common cold and other inappropriate conditions (viral)

Using antibiotics in animal feed
- respond to them in human gut

Failing complete the prescribed regimen

Using someone else’s leftover prescription

51
Q

4 antibiotic resistance mechanisms

A

Blocking entry

Inactivating enzymes
- Chomp open beta lactam ring so ineffective

Alteration of target molecules
- Ribosome subtly change

Efflux of antibiotics
- Straight in and out

52
Q

chemotherapeutic drug

A

any chemical used in the treatment, relief or prophylaxis of a disease

53
Q

antimicrobial chemotherapy

A

the use of chemotherapeutic drugs to control infection

54
Q

prophylaxis

A

use of a drug to prevent imminent infection of a person at risk

55
Q

antimicrobials

A

all inclusive term for any antimicrobial drug, regardless of its origin

56
Q

antibiotics

A

substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other micro-organisms

57
Q

semisynthetic drugs

A

drugs which are chemically modified in the laboratory after being isolated from natural sources

58
Q

synthetic drugs

A

the use of chemical reactions to synthesise antimicrobial compounds in the labratory

59
Q

narrow (limited) spectrum

A

antimicrobials effective against a limited array of microbial types - e.g. drug effective mainly on gram-positive bacteria

60
Q

broad (extended) spectrum

A

antimicrobials effective against a wide variety of microbial types - e.g. both gram positive and negative

BDS2 BAMS (54 decks)

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