Molecular mechanisms of antimicrobial resistance in bacteria by highlighting the aspects of antimicrobial resistance through a discussion of: Bacterial strategies involved in resisting antimicrobial actions and The molecular basis for bacterial resistance to antimicrobial actions some note kept in phrase are completed visualizing the picture.

1. SE
MOLECULAR MECHANISMS OFANTIMICROBIAL RESISTANCE IN BACTERIA
BY
MOTUMA DEBELO
(5th YEAR)
A SEMINAR PAPER PERESENTED FOR THE COURSE ON ANIMAL HEALTH
(BMSC 502)
ADDIS ABABA UNIVERSITY
COLLEGE OF VETERINARY MEDICINE AND
AGRICULTURE
DEPARTMENT OF BIOMEDICAL SCIENCE
MARCH, 20/2014
BISHOFTU, ETHIOPIA
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2. 1.INTRODUCTION
Microbes are living organisms
They include bacteria,virus and others
Some microbes cause disease
Microorganisms to servive they should tolerate or disrupt
mech of actn of antimicrbls through differ ways
Antimicrobials used in animals and agriculture lead to spread
of resistant strain to human population
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3. CONT……
Since there is no work done on molecular mechanisms of
antimicrobial resistance in bacteria in Ethiopia
by studying this mechanism of resistance I want to rectify
antibiotic wide reaction problems or
I want to complete picturing of the problem as society
are becoming aware of the resistance and raise up to
combat infectious disease.
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4. CONT…..
Therefore, the objectives of my seminar paper are;
to highlight the aspects of antimicrobial resistance
through a discussion of:
Bacterial strategies involved in resisting
antimicrobial actions and
The molecular basis for bacterial resistance to
antimicrobial actions
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5. 2. MOLECULAR MECHANISMS OF ANTIMICROBIAL RESISTANCE IN BACTERIA
To realize it requires,
understanding of bacterial structure and function
Antibiotics selectively kill bacteria because of
Structural and metabolic differ
gram –ve bacteria have;
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6. COTN…..
Gram +ve bacteria have no

7. CONT…
The major problem of the emergence of resistant
bacteria are due to:
misuse and overuse of antibiotics
antimicrobial sold over the country without prescription
Inappropriate prescription and treatment
before laboratory investigations
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8. 3. TYPES OF MOLECULAR MECHANISMS OF RESISTANCE
There are two types of mol mech of bacterial
resistance.
3.1. INTRINSIC RESISTANCE (INSENSITIVITY)
Is absence of cellular antibiotic susceptibility e.g mycoplasm is resistant
to penicillin b/c it lack cell wall
In this type, microbes are resistant through their inherent structure or
functional characteristics
Natural insensitivity can be due to;
* lack of affinity of the drug for the bacterial target
* inaccessibility of the drug into the bacterial cell
* extrusion of the drug
* innate production of enzymes that inactivate the drug.
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9. EXAMPLES OF INTRINSIC RESISTANCE AND THEIR RESPECTIVE MECHANISMS
Organisms Natural resistance
against:
Mechanism of resistance
Gram-positive bacteria Aztreonam (a beta-lactam they lack penicillin binding
proteins (PBPs)
Gram-negative bacteria Vancomycin they lack to uptake it b/c
may be their atomic differ or
lack porin channel
Klebsiella spp Ampicillin (a beta-lactam beta-lactamases producn
that destroy ampicillin
before the drug can reach
the PBP targets

10. 3.2. ACQUIRED RESISTANCE
Said to occur when previously susceptible microbes
become resistant
plasmid mediated resistance tend to encode
synthesis of enzymes that modify antibiotics
plasmid reproduce it
self within a cell and spread to other cells by
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11. CONT…

12. 4. BACTERIAL RESISTANCE STRATEGIES
To survive, bacteria able to disrupt essential steps required for the
effective action of antimicrobial agent
Intended modes of action of antmcrbls are counter-acted via
four main strategies.
4.1) Reducing entry (permeability) of antimicrobial agents
impermeability of antimicrobial is inability to gain entry into site of drug target
the way which antibiotics cross bacterial
outer m/m is through porin channels but
some bacteria e.g Gram –ve are modfy cell
m/m porin channel’s; *frequency and reduce
* size entry of ant
* selectivity
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13. 4.2, EXPULSION (PUMPING OUT) OF ANTIMICROBIAL AGENTS
To be effective antimicr must present at a sufficient high [ ]
within the cell
Some bacteria posses membrane protein that
act as; export (efflux pump) that extrude antibiotic
out of the cell
as the reasult microbes cause
low intracellular [ ] of antimicrobial agent
and detoririet effect of the drug by diluting.
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14. 4.3. INACTIVATION OF ANTIMICROBIAL AGENTS
Microbes preserve themselves by destroying the
active component of antimicrobial agent
Mechanisms of rendering antmicrbl inactive is
by enzymatic hydrolysis of antibiotics

15. 4.4. MODIFICATION OF ANTIMICROBIAL TARGETS
= resistant bacteria envade antimicrobials by
reprogramming the target site to avod recog
camouflaging
and
this reasul, inspite of presence of intact
and active antimicrobial agent
No binding so
No inhibition will take place
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16. 5. MECHANISMS OF REGULATION OF ANTIMICROBIAL RESISTANCE
To prevent and control drug-resistant infections;
promote appropriate drug-use policies
* This is implemented
through a public health education on appropriate antimicr
obial drug use and prevention of GPA therapy for
humans and animals
Improved diagnostic practices, this is held
by encouraging rapid diagnosis to
guide drug prescribing
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17. CONT….
the other way of regulating antimicrobial resist
using Probiotics instead of antibiotics
* used to fight against
bacteria/pathogens
their MOA is not yet understood however few
mechanisms deduced bellow:
* exclude micrbs by competing for nutrients
* block the ligand-receptor contact
* mimic the oligosaccharide receptors
of the host cells used by pathogens to enter the
cells
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18. cont…
Phytochemicals:
* plant chemicals that are neither vitamins nor minrls
* have health-enhancing effects
Vaccination: is part of prophylaxis and it is any measures
taken to prevent illness before it occurs.
* its basis is to produce Ab quickly and in greater
number
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19. 6. CONCLUSION AND RECOMMENDATIONS
Antimicrobial resistance is the ability of a microorgan
ism to survive and multiply in the
presence of an antimicrobial agent that would normally
kill this species of microorganism.
Bacteria are able to resist the effects of antimicrobials
through preventing intracellular access and immediately
removing antimicrobial substances through efflux pumps
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20. CONT……
Antimicrobial resistance
traits are genetically coded,
and can either be intrinsic or
acquired.
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21. The prevention and control of drug-resistant
infections requires measures to promote the
appropriate use of antimicrobial drugs and
prevent the transmission of infections (whether
drug-resistant or not).
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22. BASED ON THESE FACTS THE FOLLOWING RECOMMENDATIONS ARE
PIN POINTED:
A wide scale Research should have to be initiated
and encourage in the surveillance and control of
molecular mechanisms of antimicrobial drug
resistance.
All methods of antimicrobial resistance control such
as appropriate drug use policies, reducing rate of
infection transmission, improved diagnostic practice,
vaccines, probiotics, phytochemicals should
integrated and implemented with the underlying
aim of reducing goal of preserve effective of
antimicrobials.
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23. Periodic testing of drug efficacy; farms should be re
gularly monitored for antimicrobial resistance.
Public awareness creation about the problems of
antimicrobial resistance via continuous teaching farmers and
the society as the whole by veterinary extension service is
very mandatory.
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