Antibiotics

Question 1

5 types of historic antibiotics

Answer 1

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

Question 2

what is the concept of repurposing

Answer 2

designed for something else but use them for something completely different

Question 3

describe the penicillin discovery

Answer 3

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

Question 4

use of antibiotics in WWII

Answer 4

Antibiotics crucial

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

Question 5

2 types of microbial growth control

Answer 5

physical

chemical

Question 6

2 types of physical microbial growth

Answer 6

• heat sterilisation

- radiation sterilisation

Question 7

3 types of chemical microbial growth control

Answer 7

antiseptics (biological) and disinfectants (inanimate/surfaces)

natural antimicrobials

synthetic antimicrobials
- antivirals or antifungals

Question 8

what is the ideal clinical scenario

Answer 8

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

Question 9

8 examples of transmitted pathogens

Answer 9

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

Question 10

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

Answer 10

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

Question 11

4 basic methods of infection control

Answer 11

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)

Question 12

disinfectants

Answer 12

are strong chemical agents that inhibit or kill microorganisms
ideally kill

Question 13

antiseptics

Answer 13

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

Question 14

sterilants

Answer 14

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

disinfectants with added value can kill of spores

Question 15

where are disinfectants used

Answer 15

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

Question 16

antisepsis is

Answer 16

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

Question 17

what are the properties of an ideal antiseptic

Answer 17

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

Question 18

5 examples of antiseptic use

Answer 18

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

Question 19

3 classifications of antiseptics

Answer 19

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

Question 20

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

Answer 20

dentaure proteins and DNA bases

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

Question 21

what is the mechanism of action for cationic detergents

Answer 21

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

• osmotic shock
• slow it down to death

e.g. chlorohexidine

Question 22

what is the mechanism of action for for oxidising compounds

Answer 22

oxidize functional molecules in the microorganisms

- Interfere with proteins – slow down – then kill

Question 23

what are iodophores

Answer 23

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

Question 24

what can iodophores kill

Answer 24

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

one of the best
- surgical scrubs, ICU

Question 25

what type of alcohols are effective antiseptics and disinfectant agents

Answer 25

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

Question 26

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

Answer 26

90% - cleaning surfaces - preventative measure

Question 27

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

Answer 27

Denature proteins and disturb the membrane permeability of bacteria - Limited antibacterial spectrum Rapidly kill vegetative bacteria, fungi and inactivate lipophilic viruses

Question 28

what is chlorohexidine used as

Answer 28

Water soluble chlorhexidine digluconate is used as an antiseptic

Question 29

mechanism of action for chlorohexidine

Answer 29

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

Question 30

name common oxidising agent

Answer 30

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

Question 31

uses of oxidizing agents with concentration change

Answer 31

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

Question 32

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

Answer 32

short-term and long-term toxicity general biocidal activity accumulate in the environment OR in the patient’s/caregiver’s body – problematic

Question 33

2 examples of bacteria antibiotics used against

Answer 33

streptomyces bacillus

Question 34

2 examples of moulds bacteria used against

Answer 34

penicillium cephalosporium

Question 35

what are antibiotics

Answer 35

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

Question 36

2 possible mechanisms of action for antibiotics

Answer 36

bacteriostatic bacteriocidal

Question 37

4 cellular targets of antibiotics

Answer 37

cell wall cell membrane nucleic acid protein synthesis

Question 38

8 characteristics of an ideal antimicrobial agent

Answer 38

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

Question 39

4 main antimicrobial targets

Answer 39

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

Question 40

structural feature of peptidoglycan targeted by penecillin

Answer 40

Cross linked - penicillin prevents cross link become unstable Critical in terms of where antibiotics work - Cause cell lysis

Question 41

2 types of inhibitors of cell wall synthesis

Answer 41

beta- lactams glycopeptides

Question 42

beta-lactam inhibition of cell wall synthesis

Answer 42

Bind to ‘penicillin binding proteins’ Inhibition of cross-linking of cell wall Accumulation of precursor cell wall units Cell lysis

Question 43

glycopeptides inhibition of cell wall synthesis

Answer 43

Examples: vancomycin, teicoplanin Bind to terminal D-ala-D-ala residues Prevent incorporation of sub-unit into growing peptidoglycan

Question 44

how are different penicillin structures made

Answer 44

Different penicillin structures, Taken basic penicillin natural building block Chemists have made semi synthetic versions by modifying branches to make different structures

Question 45

how to antibiotics cause inhibition of protein synthesis

Answer 45

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

Question 46

how do antibiotics cause nucleic acid inhibition

Answer 46

Super coiled DNA - DNA gyrase unwinds specific section Ciproflaxcin - stops this

Question 47

3 basic points antibiotics attack on bacteria and fungi replication

Answer 47

cell wall protein nucleic acid

Question 48

what drives the increase of Antimicrobial Resistance

Answer 48

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

Question 49

what creates antibiotic resistance

Answer 49

missuse of antibiotics selects for resistance mutants

Question 50

5 examples of antibiotic missuse

Answer 50

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

Question 51

4 antibiotic resistance mechanisms

Answer 51

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

Question 52

chemotherapeutic drug

Answer 52

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

Question 53

antimicrobial chemotherapy

Answer 53

the use of chemotherapeutic drugs to control infection

Question 54

prophylaxis

Answer 54

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

Question 55

antimicrobials

Answer 55

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

Question 56

antibiotics

Answer 56

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

Question 57

semisynthetic drugs

Answer 57

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

Question 58

synthetic drugs

Answer 58

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

Question 59

narrow (limited) spectrum

Answer 59

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

Question 60

broad (extended) spectrum

Answer 60

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