Where will the new antimicrobials come from, in the present crisis of antibiotic resistance.

1. PRESENTED BY:
SUGANDHA MAHAJAN
L-2012-BS-18-IM
1
CREDIT SEMINAR:
591

2. 2

3. • When pathogenic microorganisms multiply beyond some critical mass in the face of invading
antimicrobials.
• Treatment outcome is compromised.
EXAMPLES
 Methicillin Resistant Staphylococcus aureus (MRSA),
 MDR and Pan Drug Resistant (PDR) Gram negative bacteria,
 MDR and Extensively Drug Resistant (XDR) strains of Mycobacterium tuberculosis,
 Candida species (3rd leading cause of catheter-related infection).
WHAT IS ANTIMICROBIAL RESISTANCE
(AMR)
3

4. 4
“ESKAPE”
PATHOGEN
S
E- Enterococcus
faecium
S- Staphylococcus
aureus
K- Klebsiella pneumoniae -
E. coli
A- Acinetobacter
baumannii
E- Enterobacter species 1
P- Pseudomonas
aeruginosa
IDSA

5. CONTENTS
• INTRODUCTION
• NEED FOR NEW MOLECULES
• HOW TO FIND NEW ANTIBIOTICS
 MINING THE NATURAL WORLD
 DEVELOPING SYNTHETIC MOLECULES
 MICROBIAL COMMUNITY APPROACH
 INHIBITION OF QUORUM SENSING
 CRUDE PLANT EXTRACTS
 PROBIOTIC THERAPIES
 CARBON BASED NANOPARTICLES
 ANTIBACTERIAL PEPTIDES : RIBOSOMALLY SYNTHESIZED; NON RIBOSOMALLY SYNTHESIZED
 TEIXOBACTIN
 LYSOSTAPHIN
 PRODRUG
 INSECT WORLD
• HOW TO MANAGE ANTIBIOTIC RESISTANCE
• CONCLUSION
5

6. INTRODUCTION
• Antimicrobial resistance poses a catastrophic
threat.
6
• Stagnation in drug
development.
• Fall in the number
of new drugs
coming to market

7. 7

8. HAVE WE GONE WRONG ?
• Evolution by natural selection is continually
adjusting all living things to cope better with
their environment.
• Microbes are no exception.
• WHERE WE HAVE GONE WRONG IS :
Not trying hard enough to minimize its rate.
The more antibiotics are used, the more
rapidly it will happen.
Unethical and abusive use.
8

9. ANTIBIOTIC RESISTANCE IS INEVITABLE
• Resistance is prevalent, heritable and ancient.
• Resistant microbes, having a selective advantage over
their non-resistant counterparts,
 Will survive and replicate,
 Increase in numbers and
 Spread resistance through population (Indirect
resistance). Hence it is almost inevitable.
• The resistant genes are inherited in vertical fashion
• Antibiotic resistance genes are also found on mobile
genetic elements that readily pass horizontally, even
across species (Levy and Marshall 2004).
9

10. NEED FOR NEW MOLECULES
• The long gap in the introduction of new structural classes of antibiotics—38 years
Streptogramins in 1962 Linezolid in 2000
10

11. OBSTACLES FOR ANTIBIOTIC TREATMENT
11

12. HOW CAN WE FIND NEW ANTIBIOTICS
12
Advances in
genetics and
biosynthesis can
be used to create
‘libraries’ of
molecules
Genome
mining
(Stein 2005).
Target the drug
against whatever in
the host it relies on.
(Eg. Anti influenza
drugs)
Develop drugs in a
way that targets or
neutralize the
virulence factors.

13. 1. New classes of bioactive compounds have been isolated
and structure determined.
MINING THE NATURAL WORLD: AN APPROACH
TO FIND NEW ANTIBIOTICS
13
2. Abyssomicin c - Inhibit the folate biosynthesis in MRSA-
produced by the rare actinomycetes Verrucosispora (Bister
et al 2004).
3. The genetic regulatory programs and the biochemical
processes associated with the triggering of cell death.
(Engelberg-Kulka et al 2004).

14. MICROBIAL COMMUNITY APPROACH TO NEW
ANTIMICROBIALS
A. Characterization of communities of microbiota
Design Include exploitation of beneficial and commensal bacteria in
fighting infections.
The associations in human health and disease will allow the development
of non-traditional therapeutics aimed to inhibit the growth of pathogens.
Example : The human microbiome has so far yielded only a few
antibiotics, such as
1. Lugdunin produced by Staphylococcus lugdunensis.
2. Lactocillin, produced by a vaginal bacterium.
14

15. A HUMAN COMMENSAL: LUGDUNIN
NOSE KNOWS HOW TO KILL A MRSA
• A cyclic peptide thiazolidine derivative.
• Produced by Staphylococcus lugdunensis.
• Colonizes the human nose.
• The molecule kills the potentially deadly
Methicillin Resistant Staphylococcus aureus
(MRSA) in mice and rats.
15
Black arrows - S. lugdunensis
White arrows - S. aureus

16. MODE OF ACTION FOR LUGDUNIN
16
(Zipperer et al 2016)

17. B. Manipulating bacterial signaling and communication such as
quorum sensing
• Quorum sensing A bacterial communication
system.
• Regulate the production of virulence factors.
• An attractive anti-pathogenic strategy.
• QS inhibition achieved by
 Inhibiting the synthesis of signal molecules,
 Interference with signal transport/secretion,
 Degradation of the signal,
 Inhibition of binding of the signal molecule to
the receptor and
 Inhibition of the signal transduction cascade.
17

18. INHIBITION OF QUORUM SENSING : A NOVEL
ANTIMICROBIAL STRATEGY
Three predominant classes of molecules used for
communication :
1. Acylhomoserine lactones (AHL) in Gram-
negative bacteria (Parsek et al 1999),
2. Oligopeptides/ Autoinducing peptide (AIP) in
Gram-positive bacteria (Lazazzera and Grossman
1998),
3. A Furanone called AI-2 (Miller et al 2004; Chen et
al 2002).
Used for signaling in diverse bacterial species.
 Disruption of cell-cell signaling systems might
provide novel opportunities for antibiotic therapy.
18

19. QUORUM SENSING
INHIBITORS (QSI’S) FOR
GRAM NEGATIVE
BACTERIA
19
Acyl Carrier
Protein
Fatty acyl
derivative
Amino group of S-Adenosylmethionine
(SAM)
Lux1
AHL Signals
• Cycloleucine,
• Sinefungin,
• Methylthioadenosine
(MTA)
Fatty acid
biosynthesis
• Cerulenin,
• Diazoborine

20. QSI’S FOR GRAM POSITIVE BACTERIA
• Molecular characterization of AgrD and AgrB
Glu34 and Leu41 of the AgrD C-terminal tail are
essential for
 AgrB endopeptidase activity
 AIP biosynthesis.
• Different linear peptide inhibitors targeting the
type I signal peptidase SpsB reportedly reduce
AIP-I production.
20
Demonstrated

21. QSI’S FOR AI-2
SIGNALS
• AI-2 synthesis involves two major enzymatic
steps.
21
S-adenosylhomocysteine
(SAH)
5′-methylthioadenosine
nucleosidase (MTAN)
S-ribosylhomocysteine
(SRH)
(encoded by pfs)
4,5-dihydroxy-2,3-
pentanedione (DPD)
Lux S
Homocysteine
S-Anhydroribosyl-
l-homocysteine
S-homoribosyl-
l-cysteine
AI-2

22. CRUDE PLANT EXTRACTS TO TREAT THE MULTIPLE
DRUG RESISTANT PATHOGENIC BACTERIA
• The plant components often target the bacterial QS system
via different ways:
 By stopping the signaling molecules from being synthesized
 By the luxI encoded AHL synthase
 Degrading the signaling molecules
 Targeting the luxR signal receptor
22

23. ADVANTAGES OF QUORUM
SENSING INHIBITION
• QS inhibition - a potential alternative anti-pathogenic
strategy.
• QSI’s are used in concentrations not affecting
bacterial growth.
• Exert less pressure towards the development of
resistance.
23
QSI ACTIVITY OF SAPONIN EXTRACT (SAPONIN-A
CHEMICAL COMPOUND OBTAINED FROM PLANTS)

24. PROBIOTIC THERAPIES
Aimed at
ecological
control.
Purpose- to
reduce the
distribution of
antibiotic-resistant
bacteria in
communities that
are at risk.
Extend the
lifespan of
traditional
broad-spectrum
antibiotics
In healthy community
it converts broad-
spectrum drugs into
narrow-spectrum ones.
24

25. UNDERSTANDING BIOLOGICAL PROCESSES TO
DEVISE NEW ANTIBIOTICS
Biological
understanding
required to
intervene in
microbial
pathogenesis
• The biology of stress responses.
• The DNA exchange.
• Mutagenic DNA repair processes (Cirz et al. 2005).
Alternatives to
direct killing of
microorganism
s
•Suppressing the pathogenic behavior.
•Rather than seeking inhibitors, develop chemical agents that
mimic a natural signal activating a regulatory pathway
counterproductive to the pathogen.
25
(Liu et al. 2005)

26. Contd..
Strategic
approaches
to
discovery
of anti-
infectives
• Disruption of a given gene in the presence
of an antibiotic.
• Screen for another antibiotic that inhibits
the efflux pumps.
• Combination chemotherapy in cases
where antibiotic resistance arise from
heritable mutation, could include an
inhibitor of the critical error prone
translesional DNA polymerase with dual
goals:
• to kill the pathogen more effectively
• to block emergence of drug resistance in
surviving cells
26

27. ANTIMICROBIAL ACTIVITY OF CARBON BASED
NANO PARTICLES
27
• Silver (Ag), Silver oxide (Ag2O), Titanium dioxide (TiO2), Zinc oxide (ZnO), Gold (Au),
Calcium oxide (CaO), Silica (Si), Copper oxide (CuO), and Magnesium oxide (MgO).
• Cause membrane damage in bacteria due to an oxidative stress.
• Activity depends on the length and surface functional groups of CNTs and also the shapes of the
bacteria.
Diameter-dependent
piercing
Length-dependent
wrapping On the lysis of
microbial
walls and
membranes
 Release of intracellular
components DNA and
RNA
 Loss of bacterial
membrane potential,
demonstrating complete
destruction of bacteria.
The mechanism

28. A) CARBON NANOTUBES
28

29. MECHANISM FOR THE ACTION OF CARBON
NANOTUBES
29

30. B) FULLERENES BALLS
30
The induction of cell
membrane disruption.
Cationic derivatives showed
the maximum antibacterial
effect on E.coli and
Shewanella oneidensis.
Inhibition of energy
metabolism after
internalization of the
nanoparticles into the
bacteria.
Against :
•Gram positive
•Gram negative
•Fungi
It’s derivatives can inhibit
bacterial growth by
impairing the respiratory
chain.
Water-soluble cationic
fullerene derivative could
be used in the preparation
of chemical disinfectants.

31. C) GRAPHENE OXIDE (GO)
• Bacterial membrane stress resulted from direct contact with sharp edges of
nanosheets.
• Causes RNA effluxes through the damaged cell membranes of both Gram-negative
(E.coli) and Gram-positive (S. aureus) bacteria.
• Ag-carbon nanocomplexes Inhibitory activity against some important
pathogens such as Burkholderia cepacia, Methicillin-Resistant Staphylococcus
aureus, Multidrug-Resistant Acinetobacter baumannii and Klebsiella pneumoniae.
• These nanostructures could inhibit the growth of bio-defense bacteria such as
Yersinia pestis as well.
31

32. ANTIMICROBIAL PEPTIDES OF THE GENUS
BACILLUS: A NEW ERA FOR ANTIBIOTICS
32
• Natural part of the human antimicrobial defense system.
• An elementary group of novel antibacterial, antifungal and antiviral drugs.
• Could be used in the treatment of
Infectious diseases
Parasitic infections
Cancer and HIV infection.
• AMPs kill microbes primarily through the generation of membrane pores.

33. LANTIBIOTICS: A CANDIDATE FOR FUTURE
GENERATION OF ANTIBIOTICS
• The best-characterized AMPs.
• These small microbial peptide antibiotics possess
 A variety of unusual amino acid residues
 Genetic determinants
 Biosynthesis mechanisms
On the basis of their action
• Type a : Act by forming pores.
• Type b: Inhibit particular enzymes by forming a complex with membrane bound substrates
33

34. peptides undergo
posttranslational
modifications
through the
introduction of
unusual thioether
amino acids
A putative lantibiotic
that was isolated from
the B. amyloliquefaciens
GA1 strain.
Subtilosin A,
isolated from the
wild-type strain
B.subtilis168
34
Proteolytic
removal of
leader
peptides
• Anionic
nature
• ribosomally
synthesized
• post-
translationall
y modified
A putative lantibiotic
gene cluster
containing
• structural gene
(am/A)
• genes responsible
for modification
(am/M)
• transport (am/T)
• regulation (am/KR)
• immunity (am/FE)
Identified through
genome
characterization.
ISOLATION OF LANTIBIOTIC

35. MODE OF ACTION
• The activities based on different killing mechanisms that are combined in one molecule.
• The general pictures of the lantibiotics activities may be attained by:
i) Binding to bacterial membrane and then insertion into membrane
ii) Use of receptor/docking molecules to exert structure-based activity.
35
The prototypic lantibiotic nisin inhibits peptidoglycan
synthesis and forms pores through specific interaction
with the cell wall precursor lipid II.
The mutant [A12L] gallidermin, in which the
ability to form pore is disrupted but is as
potent as wild-type gallidermin.

36. CONTD..
36

37. APPLICATION : PEPTIDES SYNTHESIZED BY
BACTERIA
Nisin
• Bacterial mastitis
• Oral hygiene
• Enterococcal infections
• Peptic ulcer treatment
• Treatment of
enterocolitis, etc.
Mersacidin & Actagardine
• Staphylococcus aureus
including MRSA
• Bacterial mastitis
• Oral hygiene
• Acne, etc.
Gallidermin & Epidermin
• Acne
• Eczema
• Follicultis
• Impetigo
• Personal care products.
37

38. FUTURE ASPECTS OF LANTIBIOTICS
• Nisin, mutacin, mersacidin etc., are in preclinical stage to be used in medical applications
• The inhibitory activities of lantibiotics against spore germination would have interesting and
potential future applications.
• Ideal therapeutic tools because of their:
 Broad specificity
 Specific action
 Rapid killing activity against various pathogens.
• Potential to combat the escalating problem of single-drug and multi-drug-resistant infectious
pathogens in the foreseeable future.
38

39. An electronic chip used to grow a previously unculturable bacterium in
the soil (now named Eleftheria terrae), and then isolate their antibiotic
chemical compounds.
Treat many common bacterial infections such as tuberculosis,
septicaemia and Clostridium difficale.
The screening tool developed is a ‘game changer’ for discovering new
antibiotics as it allows compounds to be isolated from soil producing
micro-organisms that do not grow under normal laboratory conditions.”
39

40. MECHANISM OF ACTION
 Inhibitor of cell wall synthesis.
 It acts primarily by binding to lipid
II and lipid III.
 Binding to lipid precursors inhibits
the production of the peptidoglycan
layer .
 Leading to lysis of vulnerable
bacteria.
40

41. LYSOSTAPHIN: SILVER BULLET FOR STAPH
• A recombinant enzyme Hydrolyzing the cell walls
of bacteria from a Staphylococcus genus.
• An endopeptidase Cleaves the pentaglycine
cross bridges.
• The lysostaphin enzyme can be used directly with the
EXTRACTME DNA BACTERIA kit (EM02) when
isolating DNA from the staphylococci.
41

42. MODE OF ACTION FOR LYSOSTAPHIN
Relatively short
response time in
terms of disrupting
the biofilm.
Target components of
the extracellular
matrices.
The disruption of
staphylococcal biofilms is
sufficient to destabilize the
entire biofilm matrix in
such a manner as to allow
detachment from artificial
surfaces.
Lysostaphin's capacity to
disrupt S. Aureus biofilms
appeared to be specific for
lysostaphin-sensitive S.
aureus.
42

43. APPLICATIONS OF LYSOSTAPHIN
Used as a research and
diagnostic tool when
preparing
•Staphylococcal DNA or other
cellular components
•For the preparation of
protoplasts for transformation.
The enzyme, either alone
or in combination with
other antibacterial
agents, used in the
prevention or treatment
of infectious bacterial
Staphylococcal diseases.
There are also examples
of the application of this
enzyme in food
protection.
43

44. PRODRUG
• Bio reversible derivatives of drug
molecules.
• An inactive precursor of a drug, converted
into its active form in the body.
• Undergo an enzymatic and/or chemical
transformation in vivo to release the
active parent drug
• Established tool for improving
Physicochemical
Biopharmaceutical
Pharmacokinetic properties of
Pharmacologically active agents
44

45. INSECT WORLD
• Evolutionarily successful group showing great
diversity.
• The rat tailed maggot of the drone fly produces
enzymes that can degrade the material of biofilm.
• Harlequin ladybird, produces a compound called
harmonine with a broad spectrum of
antimicrobial activity.
• Insects gut also have a great chances of carrying the
antimicrobials.
• Enterococcus mundtii (in the gut of cotton
leafworm) produces a peptide having antimicrobial
properties. This peptide, Mundticin KS, strongly
inhibited some potentially pathogenic organisms. 45

46. COCKROACHES COULD BE MORE OF A HEALTH
BENEFIT THAN A HEALTH HAZARD
The tissues of the brain and nervous system of the
insects were able to kill more than 90% of
Methicillin-Resistant Staphylococcus aureus (MRSA)
and Escherichia coli, without harming human cells.
Protecting themselves against micro-organisms?
"Insects often live in unsanitary and unhygienic
environments where they encounter many different
types of bacteria.”
46

47. ANTIBIOTIC RESISTANCE IS MANAGEABLE
Efforts to overcome technical and jurisdictional obstacles will improve the
ability to monitor resistance, anticipate its spread, and inform health-care
practitioners of its existence in the area.
Surveillance of resistance can and should build on existing resources.
Clinical laboratories in more than eighty countries have begun to build
databases and link them into international networks using free software
(WHONET) downloadable from a world health organization web site.
Several companies now collaborate with the alliance for the prudent use of
antibiotics (APUA) to merge their data for these types of meta-analyses.
47
• Predicting resistance

48. • Detecting resistance
 Diagnostics able to identify the etiology and antimicrobial
susceptibility of all infections to target the therapy precisely.
 Improved diagnostics could have a revolutionary effect.
 The procedure of judicious and specific antibiotic use would thus
help extend the useful lifetime of new antibiotics.
• Determining resistance
 Understanding the fundamental principles is a key to the ability to
manage the spread of resistance.
 Combination therapy to inhibit the emergence of resistance-Used
in the treatment of HIV (HAART therapy) and Tuberculosis
(Isoniazid, Rifampin, and Pyrazinamide).
48

49. CONCLUSION
• Action on resistance to antimicrobial drugs is needed at all levels: local, regional and global.
• European Academics Science Advisory Council (EASAC)’s academics have a responsibility to
raise public awareness and political interest in tackling the need for new medicines concluding
that “it will take political will, sound administrative organization and appropriate funding to turn
these ideas into reality.”
Hence, good science is not the only step.
• Current antibiotic-resistance crisis is associated with predictable, inexorable loss of efficacy of
our current antimicrobial arsenal but substantial economic, regulatory and scientific barriers to
the development of new antimicrobials agents.
49

50. HOW YOU CAN HELP ?
• Only use antibiotics when prescribed by the doctor.
• Always take full prescription, even if you feel better.
• Never use left over antibiotics, unnecessarily.
• Never share antibiotics with others.
Otherwise, the day is not far, when the microbes will become
resistant to every antimicrobial possible.
50

51. THANKS
51