Alternatives to antibiotics Flashcards
Why do we need alternatives?
- Development of antimicrobial resistance
- Organic production systems
- Costs of antibiotic treatments
- Consumer and market pressures
- Alternative to growth promoters
- Few new antibiotics in the pipeline
What are natural alternatives to ABs?
- Probiotics
- Prebiotics
- Synbiotics
- Postbiotics
- Bacteriophages
- Metals (copper, zinc etc.)
- Enzymes
- Phytochemicals
- Immune modulators
- Acidifying agents
- Novel compounds/antimicrobials
- Vaccines
- Faecal transplants/modulate the gut flora?
Bacteriophages?
- Viruses that infect bacteria, which then use the bacteria cell as an organic factory to
multiply themselves. - Licenced for Listeria, E. coli, Salmonella
and Campylobacter. - Used worldwide for treating burns.
Acidifying agents,
- Feed acidifiers added to livestock feed
to reduce the pH. - Organic acids
What do organic acids do?
Metals historical use?
– Sterilisation of water
– Treatment of topical and systemic infections
what metals have antibact activity?
– Silver (Ag)
– Copper (Cu)
– Zinc (Zn)
– Gallium (Ga)
– Cobalt (Co)
– Titanium (Ti)
How are metals used as AMs in medicine today ?
– Catheters
– Dressings
– Joint prosthesis
– Medical devices and contact surfaces@
How is metal used in agriculture?
- copper and sinc used as supp in livestock feed - pigs
- Silver to treat minor wounds
Describe the BROAD AM activity of metals?
– Gram-positive bacteria e.g. Staphylococcus aureus
– Gram-negative bacteria e.g. Pseudomonas aeruginosa
– Fungi e.g. Candia albicans
– Protozoan parasites e.g. Cryptosporidium parvum
Metal nanoparticles have Inc AM activity - T/F
TRUE !
– Increased surface area and reactivity
– Used in solution or as coatings for the treatment of infections
Describe Phytochemicals
- Plant extracts have been used for thousands of years as medicines.
- Modern scientific research has identified compounds within plants that are
responsible for their biological activity. - Phytochemicals – biologically active, secondary metabolites from plants
What are soem examples of Phytochemicals?
– Polyphenols
– Essential oils
– Tannins
– Terpenoids
– Alkaloids
Which phytochemicals have been researched?
– Epigallocatechin gallate (EGCG) – a component of green tea
– Theaflavins –found in black tea
– Quercetin – a constituent of many fruits
Describe broad activity of Polyphenols?
– Bacteria e.g. P. aeruginosa, Acinetobacter baumannii, S. aureus &
Enterococci spp.
– Viruses e.g. Influenza A & B
– Fungi/yeast e.g. C. albicans, Aspergillus spp.
– Protozoa e.g. Giardia spp.
Describe potential uses of polyphenols furhter?
- Polyphenols show synergy with antibiotics against MDR bacteria.
- Potential for treating traumatic/burn wound infections caused by MDR bacteria.
- Clinical trials indicate polyphenols are well tolerated by humans and animals,
although systemic bioavailability is low.
– Polyphenol nano-carriers have been shown to overcome this
Describe oregano?
- Commonly used in poultry feed/water.
- Applied as an essential oil.
- Carvacrol and thymol, the two main phenols that constitute about
78–85% of oregano EOs
Garlic?
- Allicin is the active ingredient in garlic which has antibacterial properties
against a variety of microorganism. - Used in livestock and some companion animals.
- Frequently added to feed.
Thyme?
- Commonly used in poultry feed/water.
- Applied as an essential oil.
- The most important compounds of thyme EO are the phenols thymol (44–
60%) and carvacrol
Honey?
- Low water content
- High hydrogen peroxide levels
- Naturally acidic
- Manuka honey
What is the result of a stressed/ disturbed microflora?
- Low weight gain
- Respiratory disease
- More frequent diarrhoea
- High morbidity and mortality rates.
What benefits of modulating the microflora?
- Novel methods of controlling diseases
- Reduce pathogen carriage (e.g. Campylobacter)
- Improve feed conversion ratios
- Improve environmental conditions for animals
- Improve welfare standards for animals
- Alternative to antimicrobials
How can we modulate microflora?
- Prebiotics
- Probiotics
- Synbiotics
- Postbiotics
- Phage therapy
- Enzymes
- Phytochemicals
- Metals (copper, zinc etc.)
- Next generation growth promoters/novel compounds
- Vaccines
- Acidifiers
- Faecal transplants
Descrieb probiotic use?
- GRAS – Generally regarded as safe.
- E.g. Lactobacillus, Bifidobacteria, Enterococci,
Streptococcus.
How do probiotics work ?
– Allowing out-competition of pathogens
* Reducing available receptor sites
* Modulating the environment
* Modulating pathogen behaviour
– Producing anti-microbial compounds
– Altering the immune response of the host
What are prebiotics?
- Prebiotics are non-digestible (by the host) food ingredients that have a beneficial effect through their selective metabolism in the intestinal tract.
- Natural compounds found in soybeans, human breast milk, chicory roots, oats.
How to prebiotics work?
- Unlike probiotics, which are live bacteria, prebiotics are carbohydrates that act as food for the good bacteria.
- Prebiotics are not destroyed, digested or absorbed in the upper GI tract and therefore reach the gut where good
bacteria reside. - Prebiotics provide a natural way of increasing the number and activity of the beneficial bacteria already resident in
the colon.
What are some common examples of Prebiotics?
– Galactooligosaccharides (GOS)
– Fructoologosaccharides (FOS)
– Inulin
– β1-4 mannobiose
– Lactulose
