33. Antibiotics Flashcards
(53 cards)
1
Q
Essay plan structure
A
- INTRODUCTION
-
BACTERIAL SURFACE STRUCTURES
- Gram stain technique
- Peptidoglycan
-
Gram negative cell structures
- Outer membrane
- Lipopolysaccharide (LPS)
- Porins
- Type 3 Secretion Systems
-
Gram positive cell wall structures
- Teichoic acid
-
Features of both
- Flagella
- Pilli
-
CLASSIFICATION OF ANTIBIOTICS
- Bactericidal
- Inhibition of cross linking
- Inhibits protein synthesis (EGMAT
- 50 s
- 30s
- Myobacterium (iconiazid)
- Bactericidal
- CONSIDERATION OF ADMINISTRATION
-
GENETIC BASIS OF BACTERIAL RESISTANCE
- Chromosomal mediated resistance
- Transposon mediated resistance
- Plasmid mediated resistance
-
BIOCHEMICAL BASIS OF RESISTANCE
- Drug inactivation
- Modification of dug target
- Reduced intracellular concentration
- Increased efflux
- Biofilm formation
-
SELECTION PRESSURES
- Hospitals
- FUTURE DIRECTION
2
Q
Cell summary
A
-
(DD–)Transpeptidase (structural)
- Penicillin (beta–lactam)
- Cephalosporins
-
Blocks bacterial RNA polymerase (transcription)
- Rifampicin (rifamycins)
- Inhibit synthesis of 50s ribosome subunit (translation)
- Erythromysin (macrolide) prevents A–>P
-
Inhibits 30s ribosome subunit (translation)
- Gentamycin (aminoglycoside) - acceptance of incorrect AA-tRNA complexes
- Tetracyclin - blocks A site
-
Inhibits folic acid synthesis by inhibiting dihydropterate synthetase (replication)
- Sulfonamids
- Inhibits folate synthesis by inhibiting dihydrofolate reductase (replication)
- Trimethoprim (diaminopyridines)
-
Inhibits topoisomerase IV and DNA gyrase
- Ciprofoxacin (fluoroquinolines)
- For gram positive bacteria, topoisomerase IV is the target
- For gram negative bacteria, DNA gyrase is the target
- RNA polymerase = converting DNA into RNA (transcription)
3
Q
Qualities of a successful antibiotic
A
- Selectively toxic to the bacteria
- Target and inhibit an essential bacterial function
- Have a wide therapeutic index
4
Q
Perceptive opening about antibiotics
A
- Before the start of the 20th century, infectious diseases were the leading cause of death worldwide
- The purification of the first antibiotic by Chain & Florey 1942 was of great significance, allowing the treatment of and recovery from infected cuts and wounds that were previously fatal
- It also dramatically reduced the risk of surgery and invasive procedures that increase the risk of infection and fatality
- The initial success prompted the Golden Era for the Discovery of Antibiotics (1950-1970) and since then the development of new classes has been slow o Their relative effectiveness, coupled with few side effects resulted in their widespread, global use in the treatment of bacterial infection.
- Which, alongside their widespread use in the farming industry has led to many bacteria becoming resistance to them
- Antibiotic resistance is the ability of a bacteria to become resistant to AB they were previously sensitive to
- Multiple drug resistant bacteria result in the death of more than 25,000 people worldwide (CDC)
5
Q
Gram staining method
A
- Gram-positive bacteria have a thick mesh-like wall made up of peptidoglycan
- (50-90% of cell envelope) whereas Gram-negative bacteria have a thinner layer (10% of cell envelope)
-
Crystal violet (primary dye)
- CV+ ions and Cl- ions penetrate the cell wall of both Gram-positive and Gram-negative bacteria
- CV+ ion interacts with negatively charged components staining the cell purple
-
Iodine (trapping agent)
- Iodine (I- or I3-) interacts with CV+ and forms large complexes of crystal violet and iodine (CV-I within the inner and outer layers of the cell
-
Alcohol (decolouriser)
- Gram negative cell loses its outer lipopolysaccharide membrane and the inner peptidoglycan layer is left exposed
- CV-I complexes washed from gram-negative cell along with outer membrane
- In contrast, gram-positive cell becomes dehydrated from an ethanol treatment
-
Carbachol fuchsin (counter stain)
- Wash
- Washing away carbachol from gram positive bacteria
6
Q
Why can mycobacteria e.g. M tuberculosis not be visualised with gram stain?
A
• High cell wall lipid so no dye penetration • Use of acid fast stain instead
7
Q
Why can treponema pallidum not be visualized with gram stain?
A
• Too thin to see • Use of dark-field microscopy or fluorescence antibody instead
8
Q
Why can mycoplasma pneumonia not be visualised with the gram stain?
A
• No cell wall, small • No other alternative methods
9
Q
Why can legionella pneumophila not be visualised with gram stain?
A
• Poor uptake of red counterstain • Increased duration of counterstain to compensate
10
Q
Why can chlamydia not be visualised with gram stain?
A
• Intracellular, too small • Inclusion of bodies in infected cell cytoplasm
11
Q
Draw out the gram positive structure and describe it
A
- Envelope consists of a single plasma membrane internal to a thick layer of PG (15-180 nm thick) with a wall of teichoic acid on top
12
Q
Draw out the gram negative structure
A
- Inner membrane
- Thin peptidoglycan layer in the inner periplasmic space
- 2nm thick as opposed to 15-80 nm thick for gram-positive
- Outer membrane contains lipopolysaccharide (LPS)
- LPS = endotoxin
13
Q
Define a peptidoglycan and its function
A
- Structure
- Glycan layer of alternating N-acetylglucosamine sugars and N-acetylmuramic acid residues connected by 1,4-glycosidic bonds
- Each MurNac residue is bonded to a peptide chain of 3-5 alternating L and D amino acids
- Precise composition differs between bacteria
- Peptide chains are connected to adjacent chains by peptide cross links
- DIffers in sructure between gram-positive and gram-negative bacteria
- Function
- Rigid support of the cell
- Maintenance of cell shape
- Resistance to osmotic pressure, preventign changes in bacterial cell volume
14
Q
How do beta-lactam antibiotics target peptidoglycans? Outline the mechanism and the effect. Which gram group is more susceptible?
A
- PG is expressed only in bacteria, making it a good target for antibiotic action as host cells are unaffected
- Beta lactam antibiotics such as penicllin, carbapanems and cephalosporins inhibit PG syntehsis
- Mechanism
- They first bidn to one of many beta-lactam binding proteins
- They inhibit the transpeptidase enzyme that forms the peptide crosslinks between the peptide chains
- Effect
- This prevents PG synthesis is new bacterial cells, having a bacteriostatic effect
- Bacteriostatic effect = reducing bacterial division
- Their bactericidal effect is mediated by the activation of autolytic enzymes in the cell wall, leading to bacterial lysis
- This prevents PG synthesis is new bacterial cells, having a bacteriostatic effect
- Effectiveness
- Less effective for gram negative bacteria as they have a layer of LPS preventing penetration and making PG less accessible
15
Q
Mechanism of lysozyme-mediated destruction of bacteria
A
- Lysozyme = enzyme in human tears
- Cleave sglycosoidic bonds in the glycan backbne of PG
- Bacterial cell loses osmotic resistance and thus swells and lyses in low osmolarity solution
- Mechanism of antimicrobial defence associated with the barriers of innate immunity
16
Q
Describe the gram negative outer membrane
A
- Description
- Lipid bilayer with an asymmetric chemical distriution
- Inner leaflet made of phospholipid whereas outer leaflet is mainly made of lipopolysaccharide (LPS)
- Functions
-
Permeability barrier against compounds
- Bile
- Antimicrobials such as bile and antimicrobials
-
Produces outer membrane vesicles (OMVs)
- Host antibodies so they bind to the vesicles instead of the bacterium thus acting as an immune decoy mechanism
- Target for insertion of membrane attack complex
- Mediates bacterial lysis in terminal effector stage of complement pathway
-
Permeability barrier against compounds
17
Q
Which gram-stained bacteria are lipopolysaccharides found? Describe their structure and function of each subcomponent
A
- Gram negative
- Lipopolysaccharides = macromolecules consisting of lipids and polysaccharides that are expressed in the outer membrane of the gram-negative envelpoe
- Structure
- Lipid A
- Fatty acids and disaccharide-diphosphate group embeded in the lipid bilayer of the outer membrane
- Endotoxin component of LPS
- Core polysaccharide
- Inner core of five sugars linked to lipid A via ketodeoxyoctulonate (KDO) and outer core sugars
- O-antigen
- Polysaccharide chain attached to core polysaccharide
- Core plyscharide is made up of a repeating oligosaccharide unit consistign of 3-5 sugar residues
- Variable in length and composition
- Used to identify bacterial species such as Neisseria genus which have a non-enteric O-antigen (non-O-antigen)
- Polysaccharide chain attached to core polysaccharide
- Lipid A
18
Q
Which gram-type will porins be found on? Outlien their structure and function. Which antibiotics can pass through it?
A
- Porins = channel proteins in the outer memrbane of Gram-negative bacteria and mycobacterium
- Facilitates entry of hydrophilic substances into the periplasmmic space
-
Hydrophilic drugs enter through it
- Beta lactams
- Tetracycline
-
Hydrophobic enter by diffusion (MA)
- Aminoglycosides
- Macrolides
-
Hydrophilic drugs enter through it
-
Structure
- Made from polyppetides that assemble into beta-barrel domains and form the pore channel
- Size of around 600 Daltons
- Antibiotics must be smalelr than this to pass through
- Mutations madiate resistance
19
Q
Which Gram stain can Type 3 secretion systems be found? Define their structure and function
A
- In cell wall of gram-negative bacteria
- Used to inject bacterial toxins into the host cell cytoplasm
- Structure
- Over 20 different proteins assemble to form the secretion system
- Span the inner and outer membrane
20
Q
Which gram type has flagella? Defien theri structure and function
A
- Both gram negative and gram positive
- Description
- Flagella = long filament extending from the bacterial surface that drives cell motility/locomotion
- Conformational changes in the protein machinery drive rotation of the filament, propelling bacteria through aqueous solution
- Function
- Chemotaxis
- Directional movement in response to a chemical stimulus
- Facilitating movement towards nutrients
- Chemotaxis
- Structure
-
Basal body
- Protein complex embedded in cell envelope that drive smovement via energy from teh discharge of a proton gradient
- Utilises ATP synthase
-
Hook
- Made of flagellin E
- Length of 60 nm
- Filament
- Composed of 20,000 to 30,000 flagellin subunits in a helical arrangement
-
Basal body
21
Q
Which gram type has pilli? Describe its structure and function
A
- Both gram positive and gram negative
- Pili are filaments on the bacterial surface made of pilin subunits in a helical arrangment
- Functions
-
Attachment
- Faciliates adherence to host surface at start of infection
- Retraction of pilus towards receptors
- Importance highlighted in aivurlent mutations of Neisseria gonorrhea that lack pilli o receptors on surface of host cells
- Facilitates adherence to host surface at start of infection
-
Conjugation
- Sex pilus facilitates the transfer of plasmid DNA between donor and recipient bacterium
-
Attachment
22
Q
Define bactericidal
A
- Usually affect cell wall synthesis
- Preventign its formation and hence bacterial replication
- Cell lysis
23
Q
Define bacteriostatic
A
- Drug that inhibit:
- DNA replication
- Protein synthesis
- Growth
- Does not kill them directly
- Host immune mechanisms
- Phagocytosis
- Only effective in replicating bacteria
24
Q
Examples of bacteriostatic antibiotics
A
- Chloramphenicol
- Clindamycin
- Erthryomycin
- 50S
- EGMA = 50S & 30S
- 50S
- Sulfamethaxazoe
- Dihydroopterate synthase
- Tetracycline
- Trimethoprim
25
Examples of bactericidal antibiotics
* **_Structural_**
* **Beta-lactams**
* Cephalosporins
* Carbapenam
* **Penicillin**
* **Vancomycin**
* **_Protein synthesis_**
* **Gentamycin** (aminoglycosides)
* 30S
* 50S is bcteriostatic
* **_DNA_**
* **Fluoroquinolones**
* Topoisomerase IV & DNA gyrase
## Footnote
*GF = exception*
26
Are beta lactams bacteriocidal or bacteriostatic? Discuss the structure and mechanism of action of beta-lactams
* Bacteriocidal
* Examples
* Penicllin
* Methicillin
* Cephalosporin
* Amoxicillin
* Broad spectrum
* Effective when bacteria are replicating and new wall is being synthesised
* Gram positive bacteria due to exposed peptidoglycans
* No LPS layer
* Mechanism
* Inhibition of PG synthesis activates peptidoglycan hydrolyses that breaks down the peptidoglycan layer and leads to osmotic lysis
* Half life of 1 to 2 hours
27
Is vancomycin bacteriostatic or bacteriocidal? Describe its structure and function as well as its toxic effects
* Structure
* Glycopeptide
* Mechanism of action
* Binds directly to the **N-acetylglucosamine sugar** and **N-acetylglucamic acid** portion of the PG
* D-alanyl-D-alanine
* Toxic effects
* Nephrotoxicity
* Ototoxicty
28
Describe antibiotics that affect the 50s ribosome. What is their mechanism of action?
* Structure
* Antibiotics with a membered beta-lactam ring in their structure
* Examples
* **Chloramphenicol**
* Blocks action of **petidyl transferase**
* **Erthyromyocin (macrolides)**
* * Blocks translocation of the 50s subunit
* **Clindamycin**
* Blocks tRNA attachment
* **Linezolid**
* Premature release of the mRNA
* Most effective
* Gram positive and gram negative
29
Outline the structure and function of antibiotics that target the 30S ribosome. For each, outline if they are bactericidal or bacteriostatic.
* **Aminoglycosides**
* Examples
* Gentamycin
* Most effective
* **Gram negative - aerobic**
* Bacillus
* **Gram negative - facultative bacilli**
* Corynebacteria and lactobacillus
* Mechanism
* Inhibition of the initiation complex before translation
* **Misreading of mRNA**
* Bacteriocidal
* Creates fissures in the outer membrnae
* **Tetracycline**
* Structure
* **4 rings and 2 amine groups**
* Mechanism
* **Blocking the tRNA from entering the acceptor site in the ribosome**
* Not specific to bacterial but is taken up preferentially by them
* Bacteriostatic
* Inhibits protein synthesis, preventing replication
30
Describe an antibiotic that target mRNA. Outline its structure, MOA and whether it is bactericidal or bacteriostatic
* Rifamycin
* Structure
* Amino-modified glycoside sugar
* Example
* Rifampicins
* Most effective
* Used in TB therapy
* MOA
* Inhibits RNA polymerase
* Bacteriostatic
* Inhibits protein synthesis
31
Describe the antibiotics that affect DNA synthesis, their structure and their MOA.
* **_Folate synthesis_**
* **__****Sulfonamides**
* Examples
* Sulfamethaxazole
* MOA
* Inhibit **dihydropteroate synthase**
* Not used much due to resistance
* Used in conjunction with trimethoprim
* **Trimethiprim**
* Inhibits **dihydrofolate reductase**
* **Combination therapy**
* **Reduces the emergence of resistant strains**
* **Drugs act synergistically**
* Causing greater inhibition together than each drug separately
* **Fluoroquinolines******
* Structure
* Biyclic core structure
* Examples
* Ciprofloxacin
* Most effective
* Gram positive and gram negative
* Enters cells via **porins**
* MOA
* Inhibits topoisomerase IV in gram postive
* Inhibtis DNA gyrase in gram negative
* Toxicity
* Block GABAA receptors
* Seizures
* Convulsions
32
Which antibiotic can be used against mycobacterium? Outline the mechanism
* **Iconiazid**
* ****Converted into prodrug to the active metabolite
* Blocks **fatty acid synthase**
* Inhibition of c**ell wall mycolic acid synthesis**
33
What are the factors to consider when administering an antibiotic? When are broad-spectrum antibiotics used and what would you consider?
* When giving ABs, several factors are considered:
* Tolerance / hypersensitivity
* Type of infection
* Gram type
* Strain
* Bioavailability
* Broad spectrum
* Specific uses
1. **Empirically**
* ****When the cause of infection is unknown and there is the potnetial for acute onset of disease, then swtiched to narrow spectrum
2. **Superinfections**
* Mutiple bacterial infections at once
3. **Drug resistance to narrow spectrum**
4. **Prophylaxis**
* Immunosupressed or post-surgery
* Examples: (TACQ)
* **Tetracyclines**
* 30S (*EC GT)*
* **_Amoxicillin_**
* Beta lactam
* **Chloramphenicol**
* 50s ribosome *(EC GT)*
* **Quinolones**
* Problems
* **Destruction of the microbiata and commensals leads to:**
* Resistant commensals and opportunistic pathogens
* Overgrowth of other bacteria/fungi
* Due to reduced competition
34
What are three mechanisms that a bacteria can develop resistance?
* **Chromosome** mediated
* **Plasmid** mediated
* **Transpon** mediated
35
Define chromosome mediated resistance and its significance
* Definition
* Refers to a mutation of genes encoded by the circlar chromosomal DNA
* Mutations arise spontaneously in genes that code for:
* Target protein of drug
* Transport system of the drug into the cell
* Significance
* Chromosomal mediated resistance is much less of a clinical problem than plasmid mediated resitance
* This is because the mutation rate of chromosomal genes ranges from 10-7 to 10-9
* This is much lower than the frequency of acquisition of resistance plasmids
36
Define a transposon. Describe transposon-mediated resistance and how it arises/
* Definition
* Resistance genes transferred by transpons
* Transposon = genes transferred within/between larger pieces of DNA
* Structure (TRD)
1. **Transposase**
* Catalyses the excision and reintegration of the transposon
2. **Repressor**
* Regulates the synthesis of the transposase
3. **Drug resistance gene**
*
37
Outline plasmid mediated resistance and its significance.
* Definition
* Resistance plasmids are **extrachromosomal**, **circular** or **double-stranded DNA molecules** that carry the genes for a variety of bacterial resitance mechanisms
* Significance
* **Transmitted by conjugation** with a high transmission as they replicate independently of the chromosome
* More copies in a cell
* Increases probability of transmission
* Occurs in many bacterial species
* Mediate resistance to multiple drugs
* Transmission of resistances genes between and within bacteria
* **Horizontal gene transfer**
* Intra-genomic
* Inter-genomic
38
Outline different mechanisms of intergenomic plasmid mediated resistance.
CTT
1. **Conjugation**
* Conjugation = transmission of **genetic material** from one bacterial cell to another **via sex pilus** that connects the **cytosolic compartments**
* **Main mechanism** for spread of resistance
* **Sex pilus** proteins mediates transfer
* Coded for by **conjugative plasmid** which is **then subject to transmission**
* **Non-conjugative** **plasmids** can be transferred alongside conjugative plasmids
* Common in high density bacterial populations
* Bacteria found in gut
2. **Transduction**
* Transduction = plasmid DNA in a phage is transferred to another bacterium of the same species
* Phage = bacterial virus
* Occurs between straisn fo staphylococci and streptococci
* Stages
* Phage DNA enters the bacterial cell
* Phage cuts up bacterial DNA
* Some bacterial DNA packaged into **phage heads**
* Bacterium lyses & new phage particles are released
* Injects a new bacterial cell
* This may be incorporated into bacterial chromosome
3. **Transformation**
* Transformation = uptake of DNA from the environment and incorporation of the DNA into the genome by homologous recombination
39
Outline how resistance to beta-lactam groups is achieved.
* **Staphylococcus aureus**
* Express insensitive **beta-lactam binding proteins** AKA penicillin binding proteins
* Beta-lactma binding proteins = enzymes that catalyse peptidoglycan remodelling
* Transpeptidsases
* Transglycolyases
* **MRSA**
* Acquisition of non-native gene encoding a **PBP2a**
* PB2A = version of penicillin binding protein
* Significantly lower affinity for beta-lactams
* This gene allows for cell-wall biosynthesis, target of beta-lactams to continue even int he presence of a typically inhibitory concentration of antibiotic
40
How can bacteria develop resistance to vancomycin?
* **D-Ala-D-Ala** sequence that vancomycin targets is replaced with **D-Ala-D-lactate** sequence
* Vancomycin is therefore unable to bind and inhibit **transpeptidation** during peptidoglycan remodelling/synthesis
*
41
How can mycobacterium develop reisstance to isoniazid?
* Mutation in the gene **katG** encoding **catalase-peroxidase** that renders the **target site insensitive**
* Prevents conversion of **isoniazid prodrug** to the **active metabolite**
* Active metabolite blocks **fatty acid synthase** and **prevents** inhibition of cell wall **mycolic acid synthesis**
* Target site modification
42
Which are drugs are commonly affected by resistance via porins? How does this lead to resistance?
* Porin = transmembrane proteins that form an auqoeus channel and facilitate diffusion of compounds between the bacterial cell and extracellular medium
* Examples
* Penicillin
* Erthryocin
* Macrolides
* Gentamycin
* Aminoglycosides
* Reduction in membrane porin density reduces antibiotic influx into the bacterium
43
What has been the predominant way for tetracycline resistance?
* **Class A tetracycline efflux pumps**
* High prevalence in **Enterobacteriae**
* Encoded by **tet(A) genes**
* Expression of membrane transporter proteins that promote **efflux**
44
Describe strains of bacteria that have developed multi-drug efflux pumps (MDEPs).
* Multi-drug efflux pumps = broad specficity and thus extrude a number of different AB substrates
* Antibiotics extruded
* Tetracyclines
* Sulfonamides
* Quinolines
* Bacteria
* **MRSA**
* Methicilin-resistant staphylococcus aureus
* **VRE**
* Vancomycin-resistant enterococcus
45
Define biofilm formation and its underlying mechanisms
* Biofilm = structural consortium of bacteria embedded in a self-produced polymer matrix consisting of:
1. Polysaccharide
2. Protein
3. DNA
* Function
* Promote bacterial survival and result in chornic infection
* Increased antibacterial tolerance
* Resistant phagocytosis
* How it leads to antibiotic rsistance
1. Gradient of oxygen and nutrients from top to bottom resulting in slower bacterial growth at the bottom and is thought these **slower growing bacteria confer AB tolerance**
2. Biofilms associated with **higher mutation rates**
3. Normal mechanisms (plasmids, sex pili & conjugation bridges)
4. Physical inhibition of antibiotics
5. Quorum sensing
* Mechanism by which bacteria can sense cell population and modify their gene expression to those that will be most advantageous
* Uses autoinducers / pheromones
* Targeting
* Enzymes that destroy biofilm and AB to mediate entry
* Quorum sensing inhibitors
46
Describe natural selection in antibiotic resistance
* Driving force behind the emergnece of antibiotic resistant straisn of bacteria by natural selection
* Selection pressures provoke an increase in the numbers of ABR bacteria
47
Outline the factors/policies that accelerate antibiotic resistance
* **Overprescription**
* Antibiotics prescribed unncessarily either out of uncertainty of the casue of a disease presentation or pressure from patietns, or for longer courses than required
* Empirical use of broad spectrum ABs
* **Non-prescriptive sale**
* Many ABs can be purchased **over the counter (OTC)**
* ****Promoting inappoprriate and indiscriminate AB self-administration
* **Non-compliance**
* Patients who fail to complet a full course of antibiotic therapy more likely to promote survival of resistant bacteria
* **Directly observed therapy (DOT)**
* Healthcare workers observe patiient taking the medication
* Problem for long course ssuch as TB where patietns may miss dose
* **Agriculture**
* Food producers fortify animal feed with ABs to prevent infectiosn and promote growth
* **Sub-optimal dose**
* ****Kills only a few pathogens, those mutate and replicate for persistent infection
48
Describe the role of hospitals in contributing to MRSA
* Background
* SA = gram psotive, non-motile bacteria, catalase positive, coagulase positive
* Found in human microbiata as a commensal of the nasal mucosa
* Enters into the blood/underlying tissue
* Cutaneous or mucosal barriers broken due to wounds/surgical intervention/catheters
* **Spread between SA**
* Horizontal gene transferof **staphyococus chromosome casette** (various genes involved)
* **MecA**
* Codes for **PBP-2a**
* Beta-lactam resistance
* **Beta-lactams inhibit 4 other PBPs (1, 2, 3 and 4)**
* ****Spread in hospitals due to:
* **People predisposed to infection**
* **Invasive procedures**
* **Immune compromised**
* **High selection**
* **Frequent contact between people**
49
How is resistance to chloramphenicol achieved?
* Plasmid determined enzymes
50
How is resistance to streptomyocin achieved?
* Chromosomally-determined alteration of target site
51
Outline methods to combat antibacterial resistance
* Understand the disease process
* Host pathogen interactions
* Toxin mediated disease
* Bacterial capsules
* Use the genome sequence
* Work backwards from DNA to see bacterial proteins/antigens
* Know antigenic variation prcisely
* Target antigens in combination
* Understand immunity
* Isolate memory cells
* Screen them for functional antibodies
* Clone the sequence
* Transfect into cells
* Understand complement interactions with bacteria
1. Combination therapy
* Sulfamethazole and trimethoprim
2. Reduced bacterial spread
3. Developing new antibiotics
* Linezolid (different to isoniazid)
* Prevents formation of 30s, 50s and tRNA complex
* Gram positve bacteria specific
* May be more effective than vancomycin for treating MRSA
52
What are the problems associated with combatting antibiotic resistance?
* **Use of current antibiotics**
* Shift in attitude towards infectious diseases
* **Drug devleopment**
* Not attractive for drug companies as new drugs would be rationed so would mean lower profits
* Long process to develop
* 15 years
* Expensive
* Limited number of mechansisms that ABs can act on
* If they evolve then it is harder to develop
* **Specialised diagnosis (Longitude Prize)**
* ****Idea to have a device that can be used in a clinic to quickly identify the cause of infection soa narrower spectrum AB can be used
* **£10 million prize fund** for a research time that can develop point of care diagnosis for testing the cause of infection
* Must be:
* Accurate
* Rapid
* Affordable
* Easy to use
* Potnetial one is **transcriptome**
* ****Host resposne to bacterial/viral infections is different
* Take mRNA of blood, sequence it and look for differneces in blood between bacterial adn viral
* 2 genes that are upregulated in bacteria compared to virus
53
Statistic on global prevalence of sepsis
* The **11 million deaths** from **sepsis** account for **one in five** of all deaths around the world.
